Document text
FM 3-34.331
( FM 5-232)
Topographic Surveying
HEADQUARTERS, DEPARTMENT OF THE ARMY
DISTRIBUTION RESTRICTION: Approved for public relase; distribution is unlimited.
Field Manual
No. 3-34.331
Chapter 1
Chapter 2
*FM 3-34.331
Headquarters
Department of the Army
Washington, DC, 16 January 2001
Topographic Surveying
Contents
Page
dj ie E——————MÓÁ— vii
MISSIONS, OPERATIONS, AND DUTIES ............................ enses 1-1
Survey, MISSIONS. 4e ate bett ete S ela loi eto iat 1-1
Survey Operations аны enmiendas 1-3
Survey-Personnel Duties ...................................а.. аннан 1-9
mie ELE 1-11
Фу жле tr ED NE 1-15
Survey Communication ..............................« анаан аана 1-17
PROJECT PLANNING ::...:2....... 2ана анан а аннан анаа ААН 2-1
Section | - Evaluation and Scheduling ....................................... eene 2-1
Project Ведиігетепї....................................... nene nnn nne nnnm nnn nennen 2-1
Unit. Capabilities аа 2-2
Accuracy Constraints... n quee dur a ан epe git ee aee Ee a 2-3
MIileStOries ы сна npe CPI E ni ede ОБЫР 2-3
Administrative Support ................... esses eene nnne nennen nnn nnns 2-5
Logistics SUPPO Mt г.а нда e teet А НАИ ана eg ee 2-6
Section Il - Information-Gathering Trips ................................ essere 2-8
Initial Site-Visitation Trip... nnne nnne nns 2-8
DISTRIBUTION RESTRICTION: Approved for public release; distribution is unlimited.
*This Field Manual (FM) supersedes FM 5-232, 27 September 1989, and Technical Manuals (TMs) 5-232,
1 June 1971, and 5-237, 30 October 1964. It also supersedes DA Forms 1904, 1 February 1957; 1906, 1 February
1957; 1908, 1 February 1957; 1910, 1 February 1957; 1912, 1 February 1957; 1913, 1 February 1957; 1919,
1 February 1957; 1926, 1 February 1957; 1946, 1 February 1957; 1950, 1 February 1957; 1951, 1 February 1957;
1952, 1 February 1957; 1961, 1 October 1964; 1964, 1 February 1957; 2840, 1 October 1964; 2842, 1 October
1964; 2843, 1 October 1964; 2844, 1 October 1964; 2845, 1 October 1964; 2846, 1 October 1964; 2848,
1 October 1964; 2849, 1 October 1964; 2851, 1 October 1964; 2852, 1 October 1964; 2853, 1 March 1968; 2858,
1 March 1968; 2859, 1 March 1968; 2860, 1 October 1964; 2861, 1 October 1964; 2862, 1 October 1964; 2865,
1 March 1968; and 4727, 1 September 1978.
FM 3-34.331
Chapter 3
Chapter 4
Chapter 5
Page
Administrative-Recon Trip ы ион» көи рдак ор ennemi rnnt 2-9
Project-Visitation Trip уза» эзен йин йи иу н йай SA EE E iiaa 2-9
Section Ill - Project Ехесийоп...............................- НН 2-9
SURVEY RECON... eed дыны ны Шыны ыннаны ны ЫНЫН 3-1
Section | - Recon Fundamentals ........................................ esee nennen nnns 3-1
Recon ВЋедиігетепїѕ................................. «аа... 3-1
Recon:-Party Сотробіотм::: гг: анана а АМН: 3-2
Section Il - Recon Рһаѕеѕ.............................................ннНн 3-3
Office Recon а ee ee ce edet aide a Аан 3-3
Field RECON а Em 3-4
ВесотВеройв tte oett it iere Dd ee ed 3-16
DATUMS, GRIDS, AND COORDINATE REFERENCES ........................................ 4-1
PANU Seca E EE 4-1
epo DELE 4-3
Coordinate References..................sssssssssssssseseeese esee ннн ннн ны 4-6
CONVENTIONAL SURVEY-DATA СОШЕСТІОМ.................................................. 5-1
Section | - Fundamentals ....................................-.. е 5-1
Angle Determination:............ eaae i ee nee date ene dn ee du rue 5-1
Distance: Measurement: emet etes eene 5-13
Electronic Total Stations ...................... sse eene 5-15
Section Il - Targets... cedit ilc cierres rei pendana repanda rse навана саанан 5-16
Optical-Theodolite Target Ѕеї...................................................н 5-16
AISIFTarget:SoL2s 6 seu t aee t thes tds ck А нн 5-17
Target Setup: uei Ove ede pde Pe dettes ee ee te uda 5-19
Lighted Target'Sets' sc secet et eerte e e tede 5-19
Target and Tribrach Аајиѕітепії......................................... enne 5-20
Ха EM 5-21
сбеспой ГАП Б ы анайын de cates Кии Н ЫН ЫЕНЕН 5-24
DSSCIMPUO Mees RTL 5-24
Сотропепїх аан Wied cena Se ee ee 5-25
Leveling; sito tata titt e i A eto 5-25
Quick: CHECK: i a a e E e eua E dites te iate 5-25
Data Cole Cuan а ры ко н Оны о е Кы AE а i 5-27
File Transfers н eid tite ete tele Ын 5-28
PE GMN ete tt utt des n ы К ТОЕ 5-28
Соттийісайойв E RE 5-29
Chapter 6
Chapter 7
Chapter 8
FM 3-34.331
Page
Instrument Маіпіепапсе..................................« esee nnne EEA nennen nennen nnns 5-29
Section IV - CAD Іпїегѓасе.................................-... а 5-30
Total-Station Data Collection and Іприї.................................................«.. 5-30
PIONO ты ин uuo editum н echten. 5-31
ТВАҮ\УЕНЗЕ:..: D" ————————————Ás 6-1
Starting Control ИОА 6-1
Opeñ Traverse tc thee bete Pese t esie bee t tel a Per UR ERR 6-1
Closed" TraVerse ы изыш ышын on sted аад ie Rf run e a ie RR Pre ане 6-1
FIeldwOrk:. ides pensi veo vested tees ote a eie nte Deeg eee ades 6-2
Tfaverse-StatiOls su cert n emo tet irre up ba ihe Hee ot m tena 6-3
Traverse-Party Organization ....................ssssssssssssssseeeeeeeen nennen enne 6-4
Azimuth Computations .................. sess eene nennen trennen nennt rennen 6-4
Azimuth-Bearing Angle Relationship... 6-5
Coordinate Computations ................ина нынын nnn senten 6-6
Accuracy and Specifications ...........................................«..«на нна 6-7
DIFFERENTIAL LEVELING, ........................... Не 7-1
Section I - Instruments and Equipment ............................ eese 7-1
Automatic Levels. ss kes aree net ea. 7-1
Digital;Levels:.. niei e ioi ete ER e Г Ee Cope 7-1
Optical-Micrometer Levels ........................................... анна 7-2
Leveling Rods and Ассеѕѕойеѕ............................................«..а..а 7-2
Instrument Testing and Аајиѕїтепі.....................................«.. emnes 7-2
Section Il - Precise Leveling Procedures ................................ eene 7-5
FROCOM deca I 7-5
DE Determination... ааа аннан EA el ie cea ade: 7-5
Field-Party Composition ...................... essen eene nennen nnns 7-6
Data: Recording... a erudit ide ee rd ыша 7-6
C-Factor Determination... enne nnne sinn 7-8
Center-Wire Adjustment...................sssssssssssssssseeee eene nennen nennen snnt 7-9
SIF- Determinato Nka aere I ti ect eile pre etd ated oaa 7-9
NAVSTAR ӨРӘ а л tice e pee seb cet deci em e ie Pec. 8-1
Section | - GPS Overview ..................................„«. аан 8-1
Operating and Tracking Modes ................... sese nnns 8-1
System: Configuration... eere ete dre debe ice tede 8-2
Broadcast Frequencies and Соаезѕ...............................................«« а 8-3
Broadcast Ephemeris Data ....................... sse eene ener 8-4
FM 3-34.331
Page
Section Il - Absolute Роѕіїіопіпд............................-....... ае 8-5
Absolute-Positioning Accuracies .......................eseeee eene nenne nnn 8-5
Pseudorangirg.; «xi iet ien tei e tea ННН нд Ep. 8-5
Absolute-Positioning Error Sources.....................sssssssssssssseeeeeeeenne 8-6
User Equivalent Range Еггог................................................. 8-9
ACGUFAacIOS ..:.: i tee ile em b Dit beoe eti pedis 8-9
Section Ill - Differential Precise Positioning .................................. eres 8-14
Code-Pseudorange Tracking.....................ssssssssssssseeseeeene nennen 8-14
Carrier-Phase Tracking ................... sse enne nnne nns 8-15
Vertical Measurements ...................esssssssseseseeseeseee ннн 8-17
Differential Error Sources ..................sssssssssssssssssseeeenee enne nnne ens 8-18
Differential .AcCcUuracies... «teer ettet eame 8-18
Section IV - Precise-Positioning Survey Planning ............................................ 8-19
Project-Control ACCuracy |... eerie aec dene tea dte Йаа oen anas 8-20
Network- Dosign Factors xe ee ree idee idet ee Ef d cgit 8-21
Network Design and Layout деа нн ир издание кыана ындын nennen 8-28
GPS:S Techniques... eset а indie dete inte de iiaa eund 8-31
Section V - Precise-Positioning Survey Сопаисї.............................................. 8-35
Basic GPS-S Procedures ины н Шын ыы наннын найы нанбы 8-35
Absolute Positionirig............. eee cepe АНАА a depu n dana 8-36
Ditferential Positioning... ite rt tete Perret наа ЫН 8-37
DGPS Carrier-Phase Horizontal-Positioning Ѕимеуѕ............................................ 8-39
Static; SUrVeylDg. «uo eee tee Te eco De УС К tee aan. 8-40
Stop-and-Go Kinematic Surveying ...................... sse 8-42
Kirniematie;Surveying:;...... dun in pede TR ec rre aede ыйынды: 8-43
Pseudokinematic Surveying ....................sssssssssssssseeeeeen nennen 8-44
Rapid-Static: Surveying... iie Ehe ten ebd e d ara e decas 8-45
OTE/RTIKSürveying.:.5. et ped td ин coins 8-45
Section VI - Precise-Positioning Survey-Data Processing ............................... 8-46
Processing: Techniques... ce ete ree e ete UE ectetur 8-46
Baseline Solution by Linear СотЫїпаїїоп.................... аннын. 8-47
Baseline Solution by Cycle-Ambiguity Весохегу.................................................... 8-49
Data Processing and Verification ...........................................«....« 8-49
Loop-Closure Checks ararnar aeoiee iaia йы ensem einen nnne ntes tennis entren 8-51
Data Archival... iain eee ge dente ven rede ee e e ei 8-54
Section VII - Precise-Positioning Survey Adjustments..................................... 8-54
GPS Error-Measurement Statistical Terms .................... sse 8-54
Adjustment Соп»!дегайїоп$............... иинин нынын. 8-54
Chapter 9
Chapter 10
Chapter 11
Appendix A
Appendix B
Survey Accuracy
Internal Versus External Accuracy
Adjustments
Evaluation of Adjustment Results
Final-Adjustment Reports
AIRFIELD-OBSTRUCTION AND NAVAID SURVEYS
Airport Obstruction Charts and NAVAID Surveys
FAA and FAR Standards
Airfield-Data Accuracy Requirements
Reporting... ete reete ine acce
REPORTS, BRIEFINGS, AND OPERATION ORDERS
Section | - Reports
Gerietal:.a dtt te ОГО ГЕТ
ISVT Report
Recon Report
Progress Report
End-of-Project Report
Incident Report
Report Disposition
Section Il - Briefings
Impromptu Briefing
Deliberate Briefing
Briefing Procedures
Section Ill - Survey SOP and Supporting Annexes
MENSURAL CONVERSION CHARTS
CONTROL-SURVEY STANDARDS
Differential Leveling
Horizontal-Angle Measurement
Trigonometric Observations
GPS Techniques
FM 3-34.331
Page
FM 3-34.331
Appendix C
Appendix D
vi
Page
BASIC SURVEY СОМРОТАТІОМ..............................................„...« а C-1
Computation of a Two-Point Intersection .....................sssssseeeeenneens C-1
Computation of a Grid Traverse and Side Ѕһоїѕ...................................................... C-7
Computation of a C-Factor ................sssssssssssssseseeneeeeen enne enne nene C-24
Computation of a Level Line... eene C-28
SURVEY FORMS.....::.: атаа cuneo pesce diea o aee i de vente suce sae eaa ruota ludus D-1
GLOSSARY...5.. hu ЫЫЫ Ын E eI rui Glossary-1
BIBLIOGRAPHY ................ 2 cerneret tn tne neta ЕКЕ ЕЕН НЕЕ ea banum НЬ Bibliography-1
INDEX DDR Index-1
Preface
This FM is a guide for military occupational specialty (MOS) 82D (Topographic Surveyor). It
provides techniques not found in any commercial text concerning the precise determination of
position, azimuth, or elevation of a point. Additionally, this publication describes and
standardizes procedures for performing recons, preparing station descriptions, and reporting and
briefing of survey projects.
The material in this manual is applicable, without modification, to all geodetic survey projects in
all environments (prebattle, conventional war [nuclear and nonnuclear], low intensity conflicts,
and postbattle). The contents comply with Army doctrine and international precision surveying
practices. This manual does not provide previously published surveying doctrine or theory and
may be supplemented with commercially available texts or previous editions of technical
literature.
Appendix A contains mensural conversion charts.
The proponent of this publication is HQ, TRADOC. Send comments and recommendations on
Department of the Army (DA) Form 2028 directly to United States (US) Army Engineer School
(USAES), Attention: ATSE-DOT-DD, Directorate of Training, 320 Engineer Loop, Suite 336, Fort
Leonard Wood, Missouri 65473-8929.
Unless this publication states otherwise, masculine nouns and pronouns do not refer exdusively
to men.
vii
Chapter 1
Missions, Operations, and Duties
Surveyors determine horizontal and vertical distances between objects,
measure angles between lines, determine the direction of lines, and
establish points of predetermined angular and linear measurements. After
completing field measurements, surveyors use these measurements to
compute a final report that is used for positioning by field artillery (FA),
air-defense artillery (ADA), aviation, intelligence, communications, or
construction control points. Appendix B summarizes the standards for
control surveys, Appendix C details the recommended procedures for basic
survey computations, and Appendix D includes a list of survey forms.
SURVEY MISSIONS
1-1. Army topographic surveyors support multiple types of survey missions.
These missions can be peaceti me or wartime oriented.
SUPPORT DEPLOYABLE WEAPONS SYSTEMS
1-2. Army topographic surveyors support FA and ADA deployable weapons
systems by acquiring position and azimuth data as follows:
e FA. FA is a primary user of precise positioning and orientation
information in a wartime environment. Topographic-survey support is
provided to the multiple-launch rocket-system (MLRS) units, the
corps's general-support (GS) units, and other nondivisional assets in
the corps area according to FM 6-2. FA requires that topographic
surveyors provide monumented survey control points (SCPs)
(horizontal and vertical) and azimuthal references for conventional
and inertial FA survey teams. FA sometimes requires topographic
surveyors to augment FA survey sections.
• ADA. ADA requires positioning and orientation information for ADA
systems. ADA and FA have an agreement that FA surveyors
(MOS 82C) will provide direct ADA survey support.
SUPPORT THE NATIONAL IMAGERY AND MAPPING AGENCY
1-3. The National Imagery and Mapping Agency's (М МА”) geodetic survey
division maintains US Army topographic surveyors as part of their survey
force structure. These surveyors are involved as team leaders, as team
members, and in the data-reduction process. In addition, these Army
personnel are used in areas or situations where NIMA civilian personnel are
not authorized (Saudi Arabia, Somalia, and so on). NIMA has the
responsibility to provide earth-orientation data for the Navigation-Satellite
Timing and Ranging (NAVSTAR) Global-Positioning System (GPS). МІМА
Missions, Operations, and Duties 1-1
FM 3-34.331
provides correlated World Geodetic System (WGS) 1984 (WGS-84) airfield
surveys and geographical and aeronautical database information that are
needed to support the aviation approach requirements. NIMA also determines
transformation parameters between geodetic systems. In many areas of the
world, the transformation parameters are uncertain or unreliable. During
times of conflict, Army topographic surveyors may be required to collect data
to enable NIMA to better formulate these transformation parameters.
SUPPORT THE US ARMY AERONAUTICAL SERVICES AGENCY
1-4. TheUS Army Aeronautical Services Agency (USAASA) requires periodic
airfield and navigational-aid (NAVAID) surveys and airport obstruction
charts (AOCs) according to Army regulation (AR) 95-2. These surveys are
extensive field-survey operations that provide aeronautical and other
information to support a wide range of National Airspace System (NAS)
activities. AOC surveys provide source information on—
e Position.
e Azimuth.
* Elevation.
e Runways and stopways.
e NAVAIDs.
e Federal Aviation Regulation (FAR), Part 77 (FAR-77) obstructions.
e Aircraft movement and apron areas.
e Prominent airport buildings.
e Selected roads and other traverse ways.
e Cultural and natural features of landmark value.
e Miscellaneous and special request items.
1-5. The positioning and orientation information for NAVAI Ds is required to
certify the airfield instrument-landing approaches. AOC surveys also
establish geodetic control in the airport vicinity, consisting of permanent
survey marks accurately connected to the National Spatial Reference System
(NSRS). This control and the NSRS connection ensure accurate relativity
between surveyed points on the airport and between these points and other
surveyed points in the NAS, including the navigation satellites.
SUPPORT THE US AIR FORCE
1-6. The US Air Force (USAF) requires positioning and orientation data for
the initialization of Inertial Navigation Systems (INSs), INS test pedestals,
NAVAIDs, and compass roses. The USAF relies on NIMA to satisfy all of its
positioning and orientation requirements. Army topographic surveyors are
currently assigned to assist NIMA in establishing survey control for the
USAF.
SUPPORT THE US ARMY INTELLIGENCE AND SIGNAL ELEMENTS
1-7. The intelligence and signal elements require positioning information for
remote-operated vehicles, remote sensing-and-imaging systems, antenna
systems’ geolocation and direction, inertial navigation initialization, situation
awareness, and combat identification. This information includes the following:
1-2 Missions, Operations, and Duties
FM 3-34.331
* Accuracy. The accuracy requirement for intelligence and signal
elements is similar to the accuracy expressed by FA and ADA. In
many cases, intelligence and signal units can use the SCPs
established for FA and ADA.
* Frequency and timeliness. The number of SCPs and thetimeliness
are dependent on the battlefield and the mission.
* Distribution. This survey information is distributed to each
intelligence and signal battalion's operations section, Operations and
Training Officer (US Army) (S3). Topographic surveyors are
responsible for notifying the S3 of the various datums within the area
of operation (AO). І п addition, topographic surveyors provide the 53
with the necessary parameters and instructions on how to transform
local coordinates to a predefined common grid (for example, WGS 84).
SUPPORT J OINT-LEVEL MISSIONS
1-8. During joint-level operations, topographic surveyors may be tasked to
perform a number of different missions. Topographic surveyors are capable of
providing support to allied nations for any of the aforementioned defined
areas.
SUPPORT OTHER TOPOGRAPHIC MISSIONS
1-9. These other topographic missions are defined in AR 115-11, FM 5-105,
unit table(s) of organization and equipment (TOE), and directives from higher
headquarters (H Q). These missions—
* Provide precise positioning to support the updating of the MOS 81T
(Terrain Analyst) database.
* Support construction surveyors (when projects require real-world
coordi nates).
e Establish and extend basic control for field surveys.
e Allow survey data and station description cards to be forwarded to
NIMA, the organization's survey information center (SI C), and
collocated terrain-analyst teams (upon request).
SURVEY OPERATIONS
1-10. The actual shape of the solid mass of the earth is referred to as the
topography. A geoid is defined as the surface of the earth's gravity (attraction
and rotation), which on the average, coincides with the mean sea level (MSL)
in the open undisturbed ocean. A spheroid (also called an ellipsoid of
revolution) appears as a figurethat is flattened at the poles and bulging at the
equator. It can be described using a mathematical formula that approximately
defines a part of the surface of the geoid. However, because of the great
variations in topography, many different ellipsoids exist. Because the earth's
surface is irregular and pieces of mathematical computations are unreliable,
the type of survey conducted depends on the purpose or level of accuracy
required.
Missions, Operations, and Duties 1-3
FM 3-34.331
SURVEY TYPES
Plane Survey
Geodetic Survey
1-11. In plane surveys, all points are referenced to a flat plane with curvature
wholly or mostly ignored. In geodetic surveys, all established points are
referenced to the curved surface of a spheroid and, in all computations, the
effect of curvature is computed.
1-12. Plane surveys ignore the actual shape of the earth and apply the
principles of plane geometry and trigonometry. These surveys are treated as if
the measurements were made on a flat plane, with all lines being straight.
When the survey area is less than 250 square kilometers and less accuracy is
needed, curvature can be ignored. Most localized construction projects
(highway and railroad) and boundary projects use plane surveys.
1-13. Geodetic surveys take into account the size and shape of the earth.
Since the stations in geodetic surveys are routinely spaced over extended
distances, more precise instruments and techniques are required than for
plane surveys. All observations are made on the actual curved surface of the
earth and this curvature is corrected through computations.
SURVEY METHODS
Conventional Survey
GPS Survey
1-14. Topographic surveyors use theodolites, levels, and distance measuring
equipment (DME). The automated integrated survey instrument (AISI)
provides topographic surveyors with the capability to extend control through
the use of a total station.
1-15. The NAVSTAR GPS is capable of determining accurate positional,
velocity, and timing information. The GPS provides positional and
navigational data to civilian and military communities in the form of two
positional services. The Standard Positioning Service (SPS) encompasses the
civilian user and the US Coast Guard (USCG). When using a single GPS
receiver (absolute positioning), SPS users are denied the high-accuracy,
instantaneous positioning capability of the GPS. The Precise Positioning
Service (PPS) consists of military users and authorized representatives. PPS
users can obtain high-accuracy, instantaneous positioning if the receiver is
capable of accepting the necessary cryptologic variables.
1-16. Absolute and differential (relative) positioning methods using the GPS
provide accurate and timely positional data. The method of choice depends on
the accuracy required, the equipment available, and the logistical
requirements. At present, the PPS GPS receiver, which is capable of
performing relative positioning, is the GPS-survey (GPS-S) differential GPS
(DGPS). The positioning methods are described as follows:
1-4 Missions, Operations, and Duties
FM 3-34.331
* Absolute positioning. Absolute positioning uses a single GPS
receiver and does not require known survey control. Absolute
positions can provide instantaneous (real-time) or postprocessed
positions. Known survey control is unreliable or nonexistent in
immature theaters. Topographic surveyors can establish SCPs by
using absolute positioning.
* Differential positioning. Differential positioning uses two or more
GPS receivers. One GPS receiver (reference receiver) is resident over a
known SCP. The remaining receivers (remote receivers) are used to
position points of interest. Differential positioning can be performed in
real time or through postprocessing. If real-time positioning results
are required, a communications link that is capable of transmitting
digital data must be established at the reference- and remote-recei ver
locations. This method supports distances up to 100 kilometers
between the reference and remote stations. The engineer battalions
(topographic) within the Army have PPS GPS receivers that are
capable of real-time and postprocessed differential positioning and
provide relative accuracy of approxi mately 1 centimeter.
1-17. The accuracy of GPS-S is dependent on the user's equipment (precise
lightweight GPS receiver [PLGR]) and the surveying method employed
(absolute real-time or differential). Topographic surveyors have standardized
PPS GPS receivers. These receivers have improved the efficiency and
productivity of topographic surveyors and have provided the Defense Mapping
School (DMS) and the USAES a background on the training, operational, and
research and development requirements that are necessary to successfully
field the GPS. The new GPS-S provides adequate absolute-positioning results
and is designed to provide protection in a jamming/spoofing environment. The
requirement for a PPS GPS receiver that is capable of performing DGPS when
using the military's authorized, encrypted pseudorandom noise (PRN) code (Y -
code) has been met. This receiver satisfies the positional accuracy
requirements of the Army, the Department of Defense (DOD), and joint-level
commands.
SURVEY CLASSIFICATIONS
1-18. Topographic surveyors are capable of conducting and supporting a wide
variety of surveys. Surveys are dassified as follows:
e Artillery.
e Basic control.
* Satellite.
e Construction.
e Airfield engineering and NAVAID.
e Hydrographic.
* Field classification and inspection.
* Land.
• Inertial.
Missions, Operations, and Duties 1-5
FM 3-34.331
Artillery Surveys
1-19. Artillery surveys are conducted to determine the relative positions of
weapons systems to targets. These surveys do not require the accuracy of
geodetic-surveying techniques despite the relatively large areas and long
distances. The requirements, methods, and techniques used by military FA
surveyors are detailed in FM 6-2 and Chapter 11 of this manual. ADA weapon
systems require accuracies that are obtainable only from geodeti c-surveying
techniques.
Basic-Control Surveys
Satellite Surveys
1-20. Basic-control surveys provide horizontal and/or vertical positions of
points. Supplementary surveys may originate from and can be adjusted to
these surveys. The basic-control survey of the US provides geographic
positions and plane coordinates of triangulation/traverse stations and the
elevations or benchmarks (BMs). This information is used as the basis for the
control of the US national topographic survey; the control of many state, city,
and private surveys; and hydrographic surveys of coastal waters. The
techniques and methods used by military geodetic surveyors are discussed in
this manual.
1-21. Satellite surveys determine high-accuracy, three-di mensional (3D) point
positions from signals received by NAVSTAR GPS satellites. GPS-derived
positions may be used to provide primary reference-control monument
locations for engineering and construction projects from which detailed site
plans, topographic mapping, boundary demarcation, and construction-
alignment work may be performed using conventional-surveying instruments
and techniques.
Construction Surveys
1-22. Construction surveys provide data for planning and cost estimating.
This data is essential to locate or lay out engineering works and is recorded on
engineer maps. Plane surveys are normally used for construction projects. The
methods and techniques used by military construction surveyors are detailed
in FM 5-233.
Airfield-Engineering and NAVAID Surveys
1-23. Airfield-engineering and NAVAID surveys are used to determine any
combination of the following:
e Thelocation of obstacles within 10 nautical miles of an airfield center.
* Тһе dimensions of runways and taxiways, the height of flight towers,
and NAVAIDs.
• The safe approach angles to runways and the minimum, safe glide
angle.
e The elevation of the barometer on an airfield.
* The positions and azimuths of points designated for INS checkpoints.
1-6 Missions, Operations, and Duties
FM 3-34.331
* The requirements of the Federal Aviation Administration (FAA),
United States Army Aeronautical Services Agency USAASA, or
equivalent military activity.
* The information used to assist a military-aircraft crash or disaster
incident investigation.
Hydrographic Surveys
1-24. Hydrographic surveys are made on large bodies of water to determine
channel depths for navigation and the location of rocks, sandbars, lights, and
buoys. In rivers, these surveys are made to support flood-control projects,
power development, navigation, water supplies, and water storage.
Field-Classification and Inspection Surveys
Land Surveys
Inertial Surveys
1-25. Field-dassification and inspection surveys can help to identify features
not normally revealed using a compiler (for example, political boundary lines,
names of places, road classifications, and buildings obscured by trees). These
surveys can also clarify aerial photographs by using comparisons with actual
ground conditions.
1-26. Land surveys are used to locate the boundaries and areas of tracts of
land. These surveys may be done on a city, county, state, national, or
international level.
1-27. Inertial surveys are used to determine relative positions and azimuths.
The Position and Azimuth Determination System (PADS) is now being used
extensively to support artillery surveys.
SURVEY NETWORKS
1-28. Each survey has a fundamental dassification of control points called a
network. There are several different types of networks. A network of control
areas usually establishes horizontal and vertical SCPs within a country.
These areas are all referenced to a single datum and are related in position or
elevation to each other. Networks are classified as basic, supplementary, and
auxiliary. All horizontal networks in the US are referenced to the North
American Datum (NAD) of 1927 (NAD 27) and the NAD of 1983 (NAD 83)
(NAD 83 and WGS 84 are the same), with coordinates currently being
published in both. The National Geodetic Vertical Datum of 1929 (NGVD 29)
and the North American Vertical Datum of 1988 (NAVD 88) are used for
vertical control points. Within the continental US (CONUS), the following
terms are used:
Basic Horizontal-Control Networks
1-29. Basic horizontal-control networks are usually established by first-order
geodetic-triangulation, traverse, or GPS procedures. The lines of the basic
network are spaced at intervals of about 96 kilometers throughout a country.
Missions, Operations, and Duties 1-7
FM 3-34.331
Basic Vertical-Control Networks
1-30. Basic vertical-control networks are established by first-order
differential leveling along lines spaced from 90 to 160 kilometers apart
throughout the country. Permanent BMs (PBMs) are spaced at intervals of
about 3 kilometers on these lines.
Supplementary Horizontal-Control Network
1-31. Supplementary horizontal-control networks are usually established by
second-order survey techniques. These supplementary networks are used to
fill in the areas between the basic-control lines. Ultimately, either a basic or a
supplementary network station will be spaced at intervals of about 6 to 16
kilometers across a country.
Supplementary Vertical-Control Network
1-32. Supplementary vertical-control networks are established by second-
order differential leveling. These lines are run within the basic-control lines to
provide a planned control-line spacing at intervals of about 10 kilometers.
PBMs are emplaced at intervals of about 2 kilometers apart on these lines.
Auxiliary Horizontal-Control Networks
1-33. Horizontal auxiliary-control networks are usually established by
second- or third-order survey techniques. They provide localized control to be
used by surveyors for artillery control, construction-engineering surveys,
mapping projects, or other positioning requirements. As more states and other
agencies require geodetic accuracy for boundary and property surveys, they
will use these networks.
Auxiliary Vertical-Control Networks
1-34. Auxiliary vertical-control networks are established by third-order
differential leveling and are used to provide localized vertical control. They
are also used to support artillery, construction, and engineering projects.
SURVEY EQUIPMENT
Conventional Survey Equipment
1-35. Topographic surveyors have theodolites, levels, and electronic DME
(EDME) within their inventory. TheAISI provides topographic surveyors with
the capability to extend control in a timelier and more efficient manner. The
AISI is a total station that combines angular, distance, and vertical
measurements into a single electronic instrument that is designed to digitally
record and transfer data into a personal computer (PC).
NAVSTAR GPS
1-36. The NAVSTAR GPS is capable of determining accurate positional,
velocity, and timing information. The PPS consists of military users and
authorized representatives. A PPS user can obtain high-accuracy
instantaneous positioning if the receiver is capable of accepting the necessary
1-8 Missions, Operations, and Duties
FM 3-34.331
cryptologic variables. When two or more receivers are used, it is called DGPS
surveying. The error values are determined and removed from the survey
either by real-time processing or postprocessing of the data. Thetype of DGPS
survey used is dependent on accuracy requirements. There are two basictypes
of DGPS surveys—static and dynamic.
* Static survey. Static surveying uses a stationary network of
receivers that collect simultaneous observations over a predetermined
timeinterval and yield the best accuracy.
* Dynamic survey. Dynamic surveying uses one stationary receiver
and any number of remote or roving receivers. It allows for rapid
movement and the collection of data over a large area. When operating
in the real-time mode, the roving receiver can provide very accurate
positions almost instantaneously on the battlefield.
Computer Information Systems
1-37. Surveying has become a digital science. Modern survey systems work
with software specifically designed to process field data, perform
computations, and produce a precise product, whether it be a GPS network, a
digital database, or a computer-aided design (CAD) and drafting (CADD).
GPS-S computations require a PC to process large amounts of mathematical
variables. Efforts should be ongoing to obtain or upgrade to the fastest system
available. Computer resources are standardized throughout TOE units with
topographic surveyors. Application (such as databases or word processing)
and functional (such as adjustment or CAD) software packages have increased
the efficiency and productivity of topographic surveyors. The SIC collects and
disseminates the positioning and orientation requirements for such
organizations as NIMA, FA, ADA, Armor, and the USAF and maintains a
digital database capable of archiving, querying, and manipulating survey
control. Topographic surveyors are equipped with common GPS hardware and
software and CAD and survey-application software.
SURVEY-PERSONNEL DUTIES
MOS 82D10
1-38. Topographic surveyors supervise and/or conduct surveys to provide
control data for mapping, artillery, and aviation support and supervise or
perform topographic or geodetic computations. Duties for MOS 82D (at each
skill level) are identified below.
1-39. Skill level 1 surveyors—
e Record topographic-survey data.
e Operate and collect data with a GPS, electronic and mechanical
theodolites, EDME, and differential-leveling equipment.
e Perform topographic computations; compute elevations of tidal BMs
and baselines; and transport, set up, operate, and maintain
equipment according to written, oral, or visual instructions from
supervisors.
e Prepare abstracts of field data for final computations.
Missions, Operations, and Duties 1-9
FM 3-34.331
MOS 82D20
MOS 82D30
MOS 82D40
Assist in the emplacement and recovery of control stations and
prepare station description cards.
Compute abstracted survey data for final tabulation.
1-40. Skill level 2 surveyors—
Transport, set up, operate, and maintain equipment according to
written, oral, or visual instructions from supervisors.
Make field checks to ensure that field measurements meet project
specifications and dassifications.
Perform observations and compare, standardize, and calibrate survey
equipment.
Input field-survey data into CAD programs and process CAD data into
final products.
Transfer, process, and adjust GPS data by using survey software and
PCs.
Compute and adjust first-, second-, and third-order horizontal- and
vertical-control surveys.
Perform preliminary and field computations to verify field
observations for control surveys and compute preliminary values of
horizontal and vertical control points.
Convert grid and geodetic coordinates and transform (in the same
system) coordinates and azimuths from one zone to adjacent zones.
Operate and write programs for programmable electronic calculators.
Operate PCs.
Direct and control personnel when acting as a survey-party chief.
. Skill level 3 surveyors—
Supervise and direct topographic surveys.
Prepare project progress reports and conduct project briefings.
Recommend the method of computation and adjustment and the need
for additional data.
Evaluate and verify results of all computations.
Direct the transportation, setup, operation, and maintenance of
equipment according to written, oral, or visual instructions.
Perform a survey recon (to include picture-point selection) and main
and secondary survey-station placement and evaluate field data and
theresults obtained.
Plan and analyze the collection of traverse, triangulation, leveling,
and satellite data and isolate computational or field blunders.
Supervise CAD survey operations.
1-42. Skill level 4 surveyors—
1-10 Missions, Operations, and Duties
FIELDWORK
FM 3-34.331
Plan and approve topographic surveys.
Supervise recon studies and reconnoiter survey sites to determine
special requirements of obstacles encountered.
Plan and arrange logistical support for topographic-survey activities.
Plan and organize work activities.
Coordinate surveying and computing activities.
Supervise field-survey activities in Support of task and mission
requirements.
Determine composition and operational techniques of topographic-
survey parties.
Perform quality checks on survey data.
Collect available charts, maps, control lists, aerial photographs, and
other topographic data that are necessary to maintain a deployable
database.
Disseminate survey data.
Serve as the technical authority in all survey matters.
1-43. Topographic surveyors perform most of their operational duties away
from the parent unit. Topographic surveying involves fieldwork over a project
area or battlefield. Survey fieldwork consists of making observations and
measurements; recording data; and returning the data to a computer and/or
draftsman for computation, compilation, and dissemination. Surveyors must
overcome many factors that combine to affect working conditions. They must
be constantly alert to various factors such the following:
Weather and terrain. Weather and terrain can adversely affect field
surveys. The effectiveness of optical and electro-optical instruments
can be severely reduced by fog, mist, smog, or ground haze. Swamps
and floodplains under high water can impede leveling operations.
Signals from the GPS constellation generally require a clear line of
sight to the sky. Urban and forested areas can mask or deflect the
direct signal that is needed for accurate measurements. Good recon
and proper planning can alert the field parties of the best times and
methods to use.
Personnel. The rate of progress often varies in direct proportion to
the training and experience level of the assigned personnel. The most
effective method of training personnel is under conditions where their
actions have real consequence as opposed to mere practice. On-the-job
training produces a measurable product but frequently results in lost
work due to correcting mistakes.
Equipment. Equipment reliability must be considered when setting
completion dates. Modern, well-maintained equipment can often
increase the rate of progress. Older equipment, if properly maintained
or adjusted, will yield accurate results. Repairing or replacing broken
instruments or parts will sometimes slow down or stop a field survey.
Equipment must be calibrated as part of combat checks before the
survey mission begins.
Missions, Operations, and Duties 1-11
FM 3-34.331
Purpose. The purpose and the type of survey will determine the
accuracy requirements. Control networks are established by using
high-accuracy GPS, triangulation, traverse, or leveling procedures. At
the other extreme, cuts and fills for a highway have much lower
standards. |n some surveys, distances to inaccessible points must be
determined. High-accuracy distance and angle measurements are
required so that these values, when used in trigonometric formulas,
will yield acceptable results. This type of survey is directly dependent
on the clearness of the atmosphere. Observing measurements for a
single position can be delayed for days while waiting on good weather.
Accuracy. Accuracy requirements will dictate the equipment and
techniques selected. For instance, comparatively rough techniques can
be used for elevations in site surveys, but control-network leveling
requires much more precise and expensive equipment and extensive,
time-consuming techniques.
Errors. All measurements contain some amount of error. Errors
classified as systematic and accidental are the most common
uncontrollable errors. Besides errors, measurements are susceptible
to mistakes or blunders that arise from misunderstanding the
problem, poor judgment, confusion, or carelessness. The overall effect
of mistakes and blunders can be greatly reduced by following a
preestablished systematic procedure. This procedure will be
advantageous in all phases of a survey.
Progress rates. Rates of progress vary, depending on experience and
repetition. As skill and confidence increase, so does speed. Proper
preparation and planning reduce duplication of effort and increase
efficiency.
Enemy. A hostile environment often forces a schedule adjustment.
Night work requires greater speed, fewer lights, and increased
security. Adding security forces increases the number of vehicles and
personnel, which in turn, reduces efficiency and retards even the most
ambitious time schedule.
OBSERVATION OF DISTANCES AND DIRECTIONS
1-44. Topographic surveyors observe distances and/or directions (angles) for
the following reasons:
To establish GPS, triangulation, and traverse stations for basic,
supplementary, and auxiliary control networks.
Toestablish gun and target positions for artillery batteries.
Toestablish horizontal control to support PADS.
To establish point and lines of reference for locating details (such as
boundary lines, roads, buildings, fences, rivers, bridges, and other
existing features).
To stake out or locate roads, buildings, landing strips, pipelines, and
other construction projects.
To establish lines parallel to, or at right angles to, other lines or to
determine the area of tracts of land, measure inaccessible distances,
or extend straight lines beyond obstacles.
1-12 Missions, Operations, and Duties
FM 3-34.331
e Toestablish picture points for databases.
* To do any other work that requires the use of geometric or
trigonometric principles.
OBSERVATION OF DIFFERENCES IN ELEVATIONS
1-45. Topographic surveyors observe differences in elevation (DEs) for the
following reasons:
* To establish BMs for basic, supplementary, or auxiliary vertical-
control networks.
e Todetermine DEs of terrain along a selected line for plotting projects
and computing grade lines.
* To stake out grades, cuts, and fills for earthmoving and other
construction projects.
e For trigonometric elevations of triangulation and traverse stations for
control networks and mapping projects.
e Toestablish gun and target positions for FA batteries.
RECORDING OF FIELD NOTES
Quality
1-46. Topographic surveyors record field notes to provide a permanent record
of the fieldwork. These notes may take any of the following formats:
e Field-recording booklets.
* Single-sheet recording forms.
* Digital disks or devices for automated data recording.
e Land-survey plans.
e Property plans.
e Recovery and station description cards.
e Control diagrams showing the relative location, method, and type of
control established and/or recovered.
Even the best field survey is of little value if the field notes are not complete
and clear. The field notes are the only records that are left after the survey
party leaves the field site. Surveyors’ notes must contain a complete record of
all measurements or observations made during the survey. When necessary,
sketches, diagrams, and narration should be made to clarify notes. Write
overs, erasures, or use of correction tape or fluid are strictly forbidden. These
actions, when prohibited by the unit’s survey standing operating procedure
(SOP), are cause for punishment under the Uniform Code of Military J ustice.
Recording errors are to be lined out and initialed by the recorder and the
corrected reading entered on the recording form.
1-47. Good field notes share the following qualities:
* Neatness. The lettering should conform to the gothic style portrayed
in FM 5-553. All entries should be formatted according to unit SOPs.
e Legibility. Only one interpretation should be possible. Decimal
points and commas must be clear and distinct.
Missions, Operations, and Duties 1-13
FM 3-34.331
Organization
Format
Completeness. All entries should be complete, and all resolved data
must be finished according to unit SOPs. All entries must—
= Bedoneonthe correct forms and entirely in the field. Never record
notes on scrap paper and then transcribe them to a field-recording
form. If performing an underground survey, use a covered
clipboard to protect the notes.
= Accurately describe the field experience. Sketches, diagrams, and
notes will reduce or eliminate questions.
1-48. Survey notes are usually kept in a field notebook, on individual
recording forms, or in an automated data collector. Loose-leaf sheets should be
numbered serially to ensure that all sheets are kept and turned in. Regardless
of the format used, include—
The instructions for the return of the notes or cassette tapes (specify
any special-handling requirements) in case they are lost. Usually,
they should be returned to the commander of the particular unit.
An index of the field notes and a cross-reference to additional books or
binders.
A list of party personnel and their duties and the project's beginning
and ending dates.
A list of instruments used (include types, serial numbers, calibration
dates, constant values, and dates used).
A generalized sketch and description of the project.
The actual survey notes on each page that contain data. Fill out the
heading and indudethe following information:
= Тһе station names (include the establishing agency and date).
= The survey date.
= The names and survey duties of personnel (for example,
instrument operator or note keeper).
= Theinstruments used (include the serial numbers).
= Weather data.
= The actual observed data (include all required reductions).
= Pertinent notes, as required.
= Тһе observer's initials at the bottom right corner of the recording
form (indicating that the observer has checked all entries and
ensures that they are correct).
1-49. Recording of field notes takes three general forms—tabulations,
sketches, and descri ptions.
Tabulations. Numerical data is recorded in columns following a
prescribed format, depending on the type of operation, the instrument
used, and the specifications for the type of survey.
Sketches. Sketches add much to the darity of field notes and should
be used liberally. They may be drawn to scale (as in plane-table
1-14 Missions, Operations, and Duties
FM 3-34.331
surveys), or they can be drawn to an approximate scale (as in control
cards). If needed, use an exaggerated scale to show detail.
M easurements should be added directly on the sketch or keyed in
some way to avoid confusion. Sketches require the same quality as
other field notes.
* Descriptions. Tabulations with or without sketches can also be
supplemented with narrative descriptions. The description may
consist of a few words, or it may be very detailed. Survey notes become
a part of historic records, so a brief description entered at the time of
the survey may be important and helpful in the future.
1-50. Abbreviations and Symbols. Standard abbreviations, signs, and
symbols should be used in all survey notes and must be consistent with
guidelines in such publications as AR 310-50 and FMs 21-31 and 101-5-1.
Spell out words if there is any doubt about the meaning or interpretation of a
symbol or abbreviation.
1-51. Corrections. Field notes are considered legal documents and can be
used in court proceedings. As such, no erasures or write overs are permitted.
No position will be voided or rejected in the field, except in the case of
disturbing the instrument or target or observing the wrong target. In either
case, the position should be reobserved and the location of the reobserved data
should be noted in the remarks section. Follow these rules for making
correcti ons:
• No erasures. All fieldwork will be done in black or blue-black ink
(with no erasures) that is suitable for photocopying. The only
exception is the field sheet of a plane-table survey.
* No write overs. Field notes show what happened in the field. If a
number is changed, make a single slanted line through the incorrect
number. The individual making the corrections inserts the correct
number directly above ог next to the corrected value, creating the new
entry and initialing the change. A note will be entered in the remarks
column stating why the number was changed.
OFFICE WORK
COMPUTING
1-52. Surveying procedures also consist of converting the field measurements
into a more usable form. Usually, the conversions or computations are
required immediately to continue the fieldwork. At other times, they must be
held until a series of field measurements is completed. This is called office
work even though some of the operations may be performed in the field during
lapses between measurements. Some office work requires the use of special
equipment (calculators, PCs, or drafting equipment) or extensive references
and working areas. During survey operations, many field measurements
require some form of arithmetical computation. For example, adding or
subtracting DEs to determine the height of instrument (HI) or elevation
during leveling or checking angles to see that the allowable error (AE) is not
exceeded.
1-53. Office computing converts distances, angles, GPS measurements, and
rod readings into a more usable form or adjusts a position of some point or
Missions, Operations, and Duties 1-15
FM 3-34.331
ADJ USTING
mark from which other measurements can be made. This process involves the
computation of—
* Distances. The desired result is the horizontal distance between two
points. In electronic distance measurement (EDM ), the distance is
usually on a slope and has to be corrected for temperature and
barometric pressure and then reduced to the correct horizontal
distance.
* Azimuths and bearings. |n many operations, the observed angles
are converted into directions of a line from north (azimuths) or north-
south (bearings).
* Relative positions. The distance and direction of a line between two
points determine the position of one point relative to the other point. If
the direction is given as an azimuth bearing, a trigonometric formula
(using the sine or cosine of the angle multiplied by the distance) can be
used to determine a coordinate difference between the two points.
1-54. Some survey techniques are not complete until one or more of the
following adjustments are performed. Adjusting is the determination and
application of corrections to data. Adjusting provides a means of dealing with
the random errors in a survey network and causes the data to be consistent
within itself and to a given set of references. Small errors that are not
apparent during individual measurements can accumulate to a sizable
amount. In a linear adjustment, for example, assume that 100 measurements
were made to the nearest unit and required determining which unit mark is
closer to the actual measurement. Adjusting the result requires reducing each
measurement by the product that results from dividing the error by the
number of measurements. Since the measurements were only read to the
nearest unit, a single adjustment would not be measurable at any point and
the adjusted result would be correct. Some of the more precise surveys require
least-square adjustments.
* GPS network and least-square adjustment. A least-square
adjustment is the basis for correcting GPS (and traverse) networks
that use automation to compute solutions in geometry and produce
geodetic accuracy. A least-square adjustment in a survey network
allows for the computation of a single solution for each station and
minimizes the corrections made to the field observations. A least-
square adjustment uses probability in determining the values for
particular unknowns, independently weighs all field observations,
highlights large errors and blunders that were overlooked before
adjustment, and generates information for analysis after the
adjustment (including estimates of the precision of its solutions).
* Traverse. Traverse is the measurement of lengths and the
determination of directions of a series of lines between known points
that establishes the coordinates of the intermediate points. When
computed, the accumulated closing error shows up as a position
displacement of a known point. The displacement is corrected and
distributed among the intermediate (traverse) points.
1-16 Missions, Operations, and Duties
FM 3-34.331
* Elevation. Depending on the purpose, the elevations on some level
lines are computed as the measurements are taken. When the line is
closed, the DE between the measured and the known elevation is
adjusted over all the stations in theline. In higher-order leveling, only
the DEs are recorded during the measuring and all adjusting is done
at the completion of the line. The error is then distributed among the
various sections of the line.
ESTABLISHING RECORDS
CHECKING
1-55. Office computations reduce the field notes to a tabular or graphic form.
They become a permanent record and are stored for further use or subsequent
operations. Many standardized forms are available and should be used. As
long as the sheets are clearly identified and bound as a set, they are
acceptable. Normally, all field notes should be abstracted and filed separately.
The abstracts should be bound along with all computing forms into a single
binder or folder and maintained on file for further reference. All pages should
have the name and date of the person performing the work and at least one
person who verified that page. Do not dispose of or destroy any of these
records.
1-56. Surveying involves a series of checks. The field notes should be checked
by the observer, the recorder, and the party chief before they are turned in for
office work. Before computing, the assigned person should check the notes
again. Most mathematical problems can be solved by more than one method.
In checking a set of computations, it may be desirable to use a method that
differs from the original computation method. An inverse solution may be
used, starting with the computed values and solving for the field data or a
graphic solution. Each step that cannot be checked by any other means must
be checked by a totally independent recomputation by another individual. Any
errors or mistakes that are found must be resolved and rechecked before the
computation is accepted.
SURVEY COMMUNICATION
VOICE
1-57. Survey-party members may find themselves separated. The ability to
communicate with each other may mean the difference between successfully
completing a section of work or not. Even at relatively short distances (as in
site surveys or leveling operations), background noises can obscure direct
voice contact. At longer distances, such as in EDM or direction-measurement
operations, effective direct voice contact is impossible. Therefore, some other
type of communication is required.
1-58. On long lines, where hand signals are impossible, a radio must be used.
Each theater of operations or Army command has published communi cati ons-
electronics operation instructions (CEOI) that units must follow. Only
frequencies obtained through the local signal officer may be used. All
personnel must be familiar with the CEOI and the unit's communications
Missions, Operations, and Duties 1-17
FM 3-34.331
DIGITAL
SOP before using a radio. All radio communications must be kept as short and
secure as possi ble.
1-59. Over shorter distances, during all types of site surveys, the AISI
provides one-way voice communication. Two-way communication is preferred
for short distances. Most units have some type of hand-held radios, although
they are not TOE equipment. These radios should be able to communicate up
to 5 kilometers and should not be limited toline of sight only. Portability, ease
of operation, and frequency programmability should be considered when
procuring this type of communication equipment. Military hand-held radios
are readily availablein most military communities.
1-60. TOE changes are replacing frequency modulated (FM) radios with
Single-Channel Ground-to-Air Radio Systems (SINCGARSs). The need to
communicate across large distances is increasing in frequency. GPS-Ss are
conducted at distances of up to 25 kilometers and depend upon
synchronization between receivers during data collection. Any disruption from
a single station in a GPS network can result in a total loss of effort.
1-61. The primary focus of survey operations during wartime is to operate
quickly over large distances. This requires the ability to transmit data
digitally over the battlefield. The type of data will be largely or entirely GPS
data. І п order for a survey team to provide accurate positions where needed
and in a timely manner, they need to operate in real time without having to
process out the error code embedded in a GPS signal. The process of real-time
GPS surveying begins with a base-station receiver that broadcasts corrections
to the signals emanating from the GPS satellites. Army surveyors have the
following two means of transmitting this data:
* Radio modem. Surveyors have a radio modem that is designed
primarily for broadcasting DGPS corrections or raw GPS data from a
survey base station to one or more roving receivers for real-time
differential or kinematic (RTK) surveying. These radio modems
require line of sight between each radio modem. They can be set up in
a series of repeating stations that extend across the survey area. This
system is effective only over a small, local area.
* SINGARS. The primary system for data transmission over the
distances required on the battlefield is SINCGARS. GPS-S is designed
to transmit encrypted GPS data over SINCGARS. Any user that can
receive the data will have a real-time correction to the broadcast GPS
signal. This gives topographic surveyors the operational capability to
perform the mission under circumstances where GPS signals are
dithered or spoofed on the battlefield. A GPS signal can be
retransmitted over a communication network to multiple users, which
extends the range and capability of survey operations.
MISCELLANEOUS
1-62. Mirrors and lights can also be used for communication. A signal mirror
can use the sun as a light source and is a fairly accurate sighting device.
Morse code or other prearranged signals can be used to effectively
1-18 Missions, Operations, and Duties
FM 3-34.331
communicate during the day. At night, the same signals can be used with a
light.
Missions, Operations, and Duties 1-19
Chapter 2
Project Planning
Survey operations, whether under combat conditions or not, are like any
other military operation and must be carefully planned. Enthusiasm,
technical proficiency, and dedication do not make up for poor planning. All
plans must be dynamic in nature and must be constantly evaluated and
updated. This chapter addresses project planning, primarily from a
logistics and administrative standpoint. M ost of the information contained
in this chapter is concerned with prebattle operations. Some technical
planning will be addressed, but only as it impacts on logistics and
administrative support. Project planning can be divided into three phases:
evaluation and scheduling, information-gathering trips, and project
execution.
SECTION І - EVALUATION AND SCHEDULING
2-1. Evaluation and scheduling includes the initial project evaluation,
determination of the project requirements, assessment of the unit’s ability to
accomplish the project, determination of a preliminary plan and milestones,
and coordination of the necessary administrative and logistical support. After
receipt of a project directive, project planning begins. This preliminary
planning involves evaluating the directive, assessing the unit's capability, and
determining a preliminary schedule of events. It is important that all
estimates, including time and funds, be labeled as preliminary for all reports
or briefings. Many survey missions are in areas where government lodging
and meals are unavailable or impracticable. The customer must be made
aware of the scope and pace of survey operations and what the impact may be
if operations are restricted to a set schedule. This must be done to provide the
customer, supported units, or higher HQ with an accurate picture of the
extent and cost of a project.
PROJ ECT REQUIREMENTS
2-2. The first step in project planning involves evaluating the requirements
as stated in the project directive. In many instances, requests will come from
offices or units that have no real knowledge of survey requirements. The
support request must be carefully evaluated to ensure that what the customer
has ordered is, in fact, what the customer needs. This evaluation is usually
done by the survey noncommissioned officer in charge (N COIC). Generally,
the project directive can be classified in one of the following three cases of
requirement versus need:
* The customer has requested work that is more accurate than is
needed.
Project Planning 2-1
FM 3-34.331
e The customer has requested work that is less accurate than is needed.
e The customer has requested work that matches the need.
2-3. In the first case, the customer is typically not survey-oriented and only
sees the orders and classes of accuracy as words and numbers on a page. The
customer does not understand the differences and the cost implications of
each. Generally, a telephonic explanation of the differences in the orders of
accuracy will resolve most potential conflicts. In those cases where the
customer cannot be swayed from an erroneous perception of the orders of
accuracy, an explanation of the cost differences will generally change the
customer’s mind. If the customer remains adamant about the request, start
planning to accomplish the original request.
2-4. In the second case, the customer must be contacted and the differences in
the orders of accuracy explained. Since funding costs usually go up or down in
direct proportion to the order or class of accuracy, it may be difficult to change
the customer's attitude about the request. If the customer cannot be swayed,
start planning to accomplish the original request.
NOTE: Careful documentation of all contacts and conversations with the customer
should be kept, especially in the first two instances. At some future date, the customer
may realize that the survey unit gave good advice and may wish to change the initial
request. If the recommendations for change are not documented accurately, the unit
may be liable to correct a project without additional funding.
UNIT CAPABI
2-2 Project Planning
2-5. In the third case, planning can begin immediately. This is usually the
case when dealing with other military units that are routine survey users.
LITIES
2-6. Assessing the unit's ability to conduct any type of survey is perhaps one
of the most difficult tasks. Fortunately, many mechanisms exist to assist in
this evaluation. The single best indicators are the commander's and the
survey-section leader's personal familiarity with the soldiers. Since this is not
always accurate, a number of systems have been established to help in this
evaluation. Two of these systems are as follows:
* Army Training and Evaluation Program (ARTEP). ARTEPs
contain mission training plans (MTPs), battle drills, and evaluation
guides for assessing a unit's ability to conduct various team tasks.
* Unit files. These files contain information on a unit's past
performance on similar projects. They contain the names of personnel
who conducted the project and the duration time. Any previous
problems are listed and explained in great detail.
2-7. This information can prove to be very valuable, not only for assessing the
unit's ability to conduct the project, but also in planning the project as a
whole. A listing of the unit's training deficiencies can be generated. The
survey-section leader can develop a training program to address any
shortcomings. This program has to be designed around the project milestones.
The tendency to assign the most qualified personnel should be avoided.
Usually, a mix of highly qualified and entry-level soldiers should be assigned
to any project to ensure that new people get the experience they need.
FM 3-34.331
ACCURACY CONSTRAINTS
2-8. The Federal Geodetic Control Committee (F GCC) established the
Standards and Specifications for Geodetic Control Networks (SSGCN). These
standards define the orders of accuracy for geodetic work conducted in the US.
These SSGCN аге used to ensure uniformity of all work conducted to support
and extend the US National Control Network. The Army, through the US
Army Corps of Engineers (USACE), is a member of the F GCC and has agreed
to comply with the SSGCN. All Army survey activities conducted within the
US should bein compliance with these standards.
2-9. When possible, surveys in other nations should also comply. Due to
military necessity, there will be occasions when compliance is not possible due
to mission requirements. Some of these situations may involve the following:
e Projects conducted in a time of war.
e Projects conducted as training exercises designed as realistic war-
training exercises.
* Projects not intended for inclusion in the US National Control
Network.
e Projects conducted to support consumer requests that are specifically
exempt.
2-10. When feasible, all field activities should conform to the SSGCN. At some
later date, it may be determined that any given project should have been
included in the US National Control Network. If the fieldwork was in total
compliance, only the computations will need to be refined.
MILESTONES
2-11. Milestones are developed for estimating project duration and cost and
for managing personnel and resources. Milestones generally take the form of a
timeline, with the events noted as they should occur. A timeline allows a
commander or a customer to see, at a glance, how a project is proceeding. This
manual gives general tips on the development of timelines for all types of
survey activities. Under combat conditions, it may not be feasible to develop
precise timelines. The flow of a battle may dictate dramatic changes to
milestones, and most work will have to be accomplished with a very short
suspense. In these situations, developing a timeline may be time consuming
and counterproductive. Under normal prebattle operations, it is feasible and
advisable to develop milestones. Care should be taken to ensure that the
resulting timeline is not overly ambitious.
2-12. There are a number of variables associated with any timeline. These
indude, but are not limited to, the following:
e Availability and type of equipment.
e Experience of personnel.
* Terrain, vegetation, and weather.
e Extent or area of project.
e Priority of other projects.
* Enemy or adversary intervention.
Project Planning 2-3
FM 3-34.331
Table 2-1 shows typical rates of progress for various types of survey
operations. These are only rule-of-thumb estimates. Each unit must develop
its own rates-of-progress table based on the equipment and the level of
expertise of assigned personnel.
Table 2-1. Typical Rates of Progress for Third-Order Surveys Using One Survey Squad
| Р Ноигѕ рег Ѕеїир :
Ege Survey Method dca кө апсе by Average m Hu Day)
g р р Distance y
100 km 4.0 200 km
Static 50 km 3.0 150 km
10 km 2.1 40 km
Nonlinear GPS
25.0 km 2.00 NA
Kinematic/RTK 1.0 km 0.50 NA
0.1 km 0.10 NA
5.0 km 1.25 40.0 km
Traverse 2.0 km 0.75 25.0 km
1.0 km 0.50 20.0 km
Linear
200.0 m 6.0 km
Leveling (difierential, 150.0 m Minutes per setup 4.5 km
3-wire, loop)
100.0 m 3.0 km
NOTES:
1. Times are subject to delay due to the weather, the road conditions, or the tactical situation.
2. The survey squad consists of seven personnel.
3. GPS sessions are using four receivers per session.
4. The daily progress for RTK surveying is dependent on a network of repeater stations to transmit the
signal corrections between the base station and the roving receivers.
5. GPS-network coverage areas depend on the network geometry and the availability of suitable terrain
for each setup.
2-13. Project schedules can be established using several different approaches.
The two most common approaches are to establish the schedule based on a
firm start or end date. The procedures are similar in both cases, with the
following differences:
e Ifthe start date has been firmly established, then the project is laid
out from beginning to end with each event occurring as it will happen.
e Ifthe end date has been established, then the project must be planned
in reverse. That is, events that occur last must be programmed from
the end of the project backward until a start time is established.
2-14. In all cases, schedules must be realistic but not overly ambitious. Delays
due to weather, equipment, personnel shortcomings, or any other problems
must be built into the schedule. In most cases, it is better to estimate a longer
duration time and finish early than to underestimate and miss a scheduled
end date.
2-4 Project Planning
FM 3-34.331
ADMINISTRATIVE SUPPORT
2-15. Administrative support is normally concerned with documentation, both
technical and nontechnical. Technical documentation usually includes typing
reports, tabulating and preparing technical data, or preparing briefing
materials. The survey team, with limited help from clerical personnel, often
accomplish these technical administrative actions. Nontechnical
documentation usually involves personnel actions and is performed by
specialists in the Personnel and Administration Center (PAC), the Adjutant
General (AG) Office, or the finance and accounting office (FAO). This portion
covers general guidance about what should be accomplished and when,
primarily with peacetime operations conducted elsewhere than at the unit's
installation. Wartime requirements are addressed in various SOPs of the unit,
parent unit, and major Army commands (MACOMs).
PRIOR TO DEPLOYMENT
2-16. Before a survey unit deploys to another installation or area, a number of
administrative actions should be accomplished. All routine personnel actions
for survey-party members should be accomplished to ensure that there will be
minimal actions while deployed. All soldiers should make sure that their pay
portions, allotments, insurance statements, and other financial requirements
are updated. Other actions that may be required are powers of attorney and
routine medical checks. If a long duration time is anticipated, all personnel
should schedule a records review, to include promotion packets, personnel and
finance records, and emergency data cards.
2-17. After all these actions have been completed, there will theoretically be
no need for nontechnical administrative support. In reality, new actions will
be required from time to time. Therefore, the party chief should make
arrangements for handling any actions that may be required during the
project. The local installation PAC or AG should provide this information.
Depending on the nature of the required action, the party chief may be ableto
submit the paperwork through the mail. If these actions cannot be done
through the mail or telephonically, a visit to the AG at the project installation
or the nearest military facility may be required.
DURING A PROJ ECT
2-18. There will be times when a party chief or an individual is not able to
complete a required action. The home installation should provide guidance to
the party chief on how to address these problems. If the project is being
conducted on a military installation, the party chief should check in with the
local AG upon arrival, before any problems are encountered. Contact with the
AG at the project installation should be made during the recon phase and a
point of contact (POC) established. This will alert the AG that the survey unit
is in the area, and the AG will usually give any assistance they can.
2-19. As is often the case, the project may be in an area other than on a
military reservation. In theUS, there will usually be a military representative
who can assist. It may be possible to arrange for limited support from a local
office of the Army Recruiting Command, the Army Reserve, or the Army
National Guard. Regardless of the source, contact should be established before
Project Planning 2-5
FM 3-34.331
assistance is needed. Technical administrative support will usually be
nonexistent and is the responsibility of the survey team.
AFTER A PROJ ECT
2-20. Nontechnical administrative support after project completion is the
same as prior to deployment. The local PAC, AG, and FAO will handle these
actions. These actions include filing travel vouchers, initiating new personnel
actions, and reviewing personnel and finance records. The parent unit will be
able to assist with technical administrative support, which normally involves
finalizing reports and information.
LOGISTICS SUPPORT
2-21. This segment gives general guidance on the types of logistics
arrangements and planning that should be accomplished. Many of these
topics are covered in very general terms. The numerous requirements of the
various MACOMs and GS units prohibit this segment from being all-
encompassing.
MOVEMENT PREPARATION
2-22. Moving a unit of any size takes careful and thorough planning. Much of
the specific information concerning preparation for moving a survey section or
unit will be contained in the unit's or the parent organization's SOP. It is
imperative that all equipment and personnel move as cohesively as possible.
Movement plans should be developed well in advance of any anticipated
moves and should cover all contingencies. They should address moving
individual elements and/or the entire unit. Most of the requirements for
movement are described in FM 55-10, which is a concise reference manual and
should be available when preparing any movement plans. The information in
this FM is applicable to most wartime and peacetime situations. In some
cases, a MACOM will draft supplemental material.
COMMUNICATIONS
2-6 Project Planning
2-23. One of the most important and often overlooked aspects of any
successful operation is communication. During movement (regardless of the
mode of transportation), the unit will normally be dispersed in convoys.
During field-survey procedures, the field teams will be located throughout the
corps area. It is imperative that the elements of the unit have the ability to
communi cate with the command and control section.
2-24. Planning for communication support requires the same careful
attention to detail as any other aspect. Depending on the nature of the
operation, a determination must be made of how much and what type of
communication equipment will be required. Normally, there will be a mix of
landlines, portable radios, and cellular phones. After the number of devices is
established, the unit must determine how much of its own equipment is
available. If a unit does not have adequate equipment, it should arrange for
support from the customer or another organization. This is often a very
satisfactory solution if it is possible. Another solution is the local purchase of
hand-held radios. This will probably require a check with the local
FM 3-34.331
communications center to ensure that there are no frequency conflicts as a
result of nonstandard communications equipment. H owever, the unit will
often have to operate within its own equipment limitations. In this case, it will
be necessary to reevaluate the planned communications network and
eliminate some nice-to-have elements.
2-25. One of the best means of communication is the standard military radio
that is available in all units. These devices give instant access to all users.
However, there are a number of problems associated with these radios, to
indude the following major problem areas:
• Lack of user adherence to approved radio procedures.
e Potential enemy exploitation of nonsecure communications (such as
obtaining intelligence information, deception, radio direction finding,
or jamming).
e Lack of batteries and poor equipment maintenance.
e Atmospheric conditions that render the radios inoperative.
* Limited range of single receivers without radio-relay equipment.
2-26. The first two problem areas are directly related, and the solutions are
similar. All units have a CEOI that provides frequency and call-sign
allocations as well as security measures. Strict adherence to these procedures
is mandatory. All personnel and radio/telephone operators (RTOs) must be
trained in the proper procedures to ensure the denial of intelligence
information to the enemy. This will also help prevent other exploitation
procedures that any adversary may employ.
2-27. The lack of batteries and equipment-maintenance problems must be
addressed before the equipment is used. Proper maintenance on all equipment
can eliminate most problems. The entire communications system should be
checked occasionally to ensure that it is functioning as designed. Batteries
should be stored in an approved fashion and checked and replaced as needed.
2-28. Atmospheric conditions are a major problem and there are only limited
solutions. It may be necessary to establish landline communications. If this is
the best solution, a series of communications checkpoints should be developed
along travel routes and throughout the AO. This system is often cumbersome,
particularly if a move is over great distances or through undeveloped areas.
The establishment of radio relays will sometimes overcome these difficulties.
Іп a combat environment, it may be possible to contact the communications
officer in the corps and arrange for radio-repeater access.
2-29. After resolving all problems, the only aspect remaining is the use of the
equipment that has been selected. Following proper radio procedures (as
specified in the CEOI) and communications-security procedures are very
important.
MATERIAL SUPPORT
2-30. Specific details on how to procure required materials or material
support is generally found in unit SOPs. The intention of this manual is to
emphasize the importance of making advance arrangements for these
resources. As part of the planning process, an estimate of the time and
materials required must be developed. This estimate is based on past
Project Planning 2-7
FM 3-34.331
experience with similar projects and the known requirements of the present
project. These requirements should be developed without regard to the cost or
the difficulty of procurement. Determine what is needed and then figure out
how to get it. Normally, most of the material support is the responsibility of
the customer. However, this is not always true. Inability of the customer to
provide material support should be clearly documented in the reports from
information-gathering trips. In particular, the initial site-visitation trip
(ISVT) and the administrative-recon trip should result in a specific POC for
acquiring necessary materials. The unit should acquire technical supplies
through normal supply channels.
SECTION Il - INFORMATION-GATHERING TRIPS
2-31. Information-gathering trips are used to gather information on the
conduct of the project and for progress evaluation. The information gathered
will be logistical, administrative, or technical and is used to refine project
plans and milestones. The following paragraphs describe information-
gathering trips as they apply to normal prebattle operations. |n some
instances, these trips can be consolidated or eliminated. The overall need for
the various described trips will depend on a number of variables, induding—
* Theunit's familiarity with the area concerned.
e The amount of information already available concerning the project or
the supported unit.
e The anticipated duration of the project.
• Theamount of problems encountered by the unit.
INITIAL SITE-VISITATION TRIP
2-8 Project Planning
2-32. ThelSVT is basically a fact-finding mission that is normally conducted
by the survey-section leader and the project party chief. The primary function
of this trip is to gather information that will be used to plan the project and to
establish POCs for the various support functions.
2-33. AII project directives will identify an overall POC. This individual or
office is normally concerned with the results of the project and may not beable
to provide specific types of assistance that will be required. Often, the overall
POC will be able to assist in establishing a POC for administrative and
logistics requirements.
2-34. The types of support that must be arranged before any field activity
include equipment maintenance; medical and dental care; personnel actions;
supply, lodging, mess, and mail services; and personnel. These arrangements
must be geared to meet the specific needs of the recon party and to support the
general needs of the project-execution party.
2-35. For successful completion of the recon phase, all arrangements with
respect to care of personnel and equipment must be made during the ISVT.
Careful records should be maintained and memorandums of agreement
(MOAs) should be drafted as required. Chapter 11 identifies the
documentation required as a result of the ISVT.
FM 3-34.331
ADMINISTRATIVE -RECON TRIP
2-36. The purpose of the administrative-recon trip is to finalize arrangements
for the project and to plan the specifics of the fieldwork. Chapter 3 discusses
how to conduct a survey recon. During the recon, it is imperative that all
arrangements made during the ISVT be checked to ensure that they are
correct and viable. There may be a delay between the recon and the project
execution that causes some previously established POC to change. If this
occurs, a replacement POC must be established. Any unanticipated event that
occurs should be carefully documented. Chapter 11 identifies the
documentation required as a result of the recon trip.
PROJ ECT-VISITATION TRIP
2-37. The survey-section leader or a command representative will generally
conduct the project-visitation trip, which has a twofold purpose. The first is to
check on the progress of the project, which is the responsibility of the survey-
section leader. Any recurring technical problems will be discussed at length
and resolved in such a manner as to preclude recurrences. If problems have
been occurring before a visitation trip, contact with the parent unit should
have been made previously. Technical difficulties that need resolution should
not be left unresolved until a scheduled project-visitation trip. The second
funcion is to check on the health, the welfare, and the morale of the troops. It
is imperative that the commander knows how the troops are doing with
respect to the job and as individuals. If numerous technical problems have
been occurring, it is possible that some personal problems are being
overlooked. The project visitation can often resolve these problems before they
become major limiting factors on the project execution. A trip report should be
completed and included in the final project folder for historical purposes.
SECTION Ill - PROJECT EXECUTION
2-38. Project execution is the actual conduct of the project and putting the
project plans into effect. Unexpected or unusual circumstances may require
plan modifications. If all planning has been done correctly, the survey team
should arrive and be able to go straight to work without delays. As problems
occur, the POC should be contacted and the problems resolved as
expeditiously as possible. Specific details on project execution are covered in
the following chapters concerning each survey activity. Chapter 3 identifies
the documentation required for all phases of project planning and execution.
Project Planning 2-9
Chapter 3
Survey Recon
The recon party must consider special factors, as determined by the
objective of the survey, and the methods, techniques, and equipment that
will be employed. This chapter discusses general recon considerations.
Survey methods and techniques are discussed in the following chapters.
SECTION І - RECON FUNDAMENTALS
RECON REQUIREMENTS
GPS
3-1. A proper survey recon includes—
e Gathering all existing survey data about the target area.
* Testing and determining the usability and visibility of existing
stations.
* Selecting sites for the main and supplemental stations.
* Determining the monumentation requirements.
e Collecting terrain and climatic information.
e Arranging for access to private or government property.
e Checking on the availability of lodging, mess, medical, maintenance,
and other required support.
3-2. Interreceiver visibility is not required for GPS surveying. Stations can be
set according to network-design principles rather than traversing around
buildings or mountains. The only requirement for receiving GPS signals isa
clear view of the sky. Sources of electro-magnetic interference and tall
buildings should be avoided. Choose a station with no obstructions above an
inclination of 15° to 20°. Draw a station obstruction diagram to assist in the
planning of GPS sessions. Verify the station's accessibility and then draw
maps with directions to the stations and mark each station dearly. The field
crew will be іп a hurry to set up when they arrive, and unmarked stations сап
waste valuable time.
TRIANGULATION
3-3. During special surveys when the need to locate the position of a point
that cannot be occupied arises, triangulation is necessary. This technique
places special demands on the recon party. The mathematical computations
place stringent requirements on the size and shape of the geometric figures
that are used to determine coordinates. For this reason, the location of the
Survey Recon 3-1
FM 3-34.331
TRAVERSE
EDME
stations will normally be dictated to the field-recon party, based on the results
of the office recon. The recon party must ensure that the observation stations
which form the baseline are intervisible. A thorough knowledge of
triangulation criteria is absolutely necessary.
3-4. The demands for a traverse recon are less stringent than for
triangulation. Ensure that both the rear and the forward stations are visible
from each proposed station. Wherever possible, distances between stations
should be uniform. In control surveys that may become part of the US
National Control Network, the SSGCN must be satisfied. Spacing between
stations will be dependent on the EDME available.
3-5. An EDME traverse recon requires intervisibility between stations. The
minimum and maximum allowable distances are based on the EDME
characteristics and the clearance above possible obstructions. Use of infrared
EDME will be dependent on the weather.
DIFFERENTIAL LEVELING
3-6. Differential leveling should follow routes containing the least amount of
change in elevation between BMs and individual setups. The routes will
frequently follow roads with moderate traffic, so care must be taken to ensure
the safety of the leveling party.
TRIGONOMETRIC LEVELING
3-7. A trigonometric-leveling recon is accomplished when a traverse recon is
performed. When given a choice between a relatively level, a greatly elevated,
or a depressed observation, select the relatively level observation. Failure to
accurately level the instrument will cause a greater error in an elevated or
depressed obser vation.
OTHER CONTROL METHODS
3-8. Recon for other control methods will vary according to the physical
characteristics and limitations of the equipment or system used. No matter
what system or equipment is being used, the proposed station must be
accessible and the proposed station must be able to be included in the local
survey-control scheme. Stations occupied by PADS must not exceed the
maximum distance and time from the initializing station.
RECON-PARTY COMPOSITION
3-2 Survey Recon
3-9. The recon party will vary in disposition and number according to the
method of survey, the type of terrain, the available transportation, the extent
of the survey, and the density of control required. The chief of the recon party
is normally the section leader. The recon party usually consists of two to five
personnel. As a minimum, it will include the survey-party chief and the
section leader. It is also helpful to include personnel who will be instrument
FM 3-34.331
operators. The most qualified unit members should be assigned to the recon
party, because a properly designed recon will result in a survey project that is
accurate, complete, and expeditious. The recon party should be thoroughly
briefed on the project instructions and the specifications of the survey mission.
Recon is accomplished in three phases—office recon, field recon, and recon
reports.
SECTION ІІ - RECON PHASES
OFFICE RECON
EXISTING DATA
MAPS
3-10. The office-recon phase includes the gathering of existing data and a
study of applicable maps. This phase will be completed before the start of the
field-recon phase.
3-11. During the office-recon phase, the first step is to gather all existing data
on the area to be surveyed. Depending on the area, there may be a number of
sources that maintain sometype of reliable survey data. The existing data will
usually consist of trig lists, station description cards, and aerial photographs
or maps. Trig lists come in many forms, depending on the publishing agency.
A trig list may be compiled on DA Form 1959, horizontal-control data booklets
from the National Geodetic Survey (NGS), or a computer printout of
coordinates. Sources of information indude—
* Local Army units (such as map depots, FA target-acquisition (TA)
units, SIC, and survey units).
e TheNGS and theUS Geologic Survey (USGS).
e USACE district offices.
* TheUS Department of the Interior, Bureau of Land Management.
* State and local government civil-engineering or survey offices.
e Other nations. Existing data is sometimes received from the national
agency charged with the mapping of that nation. Local municipalities
and city governments also have survey information in their
engineering or land-planning offices.
e Continuously operating reference stations (CORSs) for CONUS.
3-12. Regardless of the information source, all trig lists (officially dassified or
not) must be safeguarded. Once secured, this information should be
maintained as a database for that area since it may be necessary to conduct
additional surveys in the same or an adjacent area.
3-13. Do not evaluate the existing material until all material has been
assembled and the information has been annotated on the available maps or
aerial photographs. Plot the required SCPs from the project directive, and
then evaluate the usability of existing controls. Compare the required control
method with the existing control method to determine if additional, basic
control is needed. It is possible that many required stations may be eliminated
Survey Recon 3-3
FM 3-34.331
because adequate control al ready exists. For those required stations that must
be established, a tentative route of survey is annotated on the maps.
FIELD RECON
INSPECTION
3-14. The field-recon phase is different for each survey project. A party chief
must consider and apply the lessons learned from previous projects. The
methods and techniques can be changed to suit the conditions of the current
project. A successful party chief will also employ the knowledge and ingenuity
of the survey-party personnel.
3-15. When time permits, the party chief and one other person will conduct a
preliminary field inspection of the area. When gathering information
concerning the area to be surveyed, include terrain types, tree heights, road
width, road surfaces, spacing between roads, microclimate (fog, haze, and heat
waves), and any other factors that will affect distance measuring and
intervisibility between proposed stations. The inspection may be conducted
using vehicles, helicopters, or airplanes. The results of the inspection will
determine the scheme and route for the survey.
RECOVERY AND VERIFICATION OF EXISTING CONTROL STATIONS
3-16. In areas where control is to be extended or established, there may be
control stations from earlier surveys that must be recovered and verified.
These stations should have been identified and annotated on overlays during
the office-recon phase and will serve as starting points for proposed GPS
networks, traverse lines, or level lines. The existing stations should be
located, described, and verified for accuracy, before using them for extending
control.
Existing Control Stations
3-17. Existing control stations (and their establishing surveys) follow similar
patterns. Recognizing and associating the patterns with the terrain types will
assist the surveyor in locating existing stations.
e Triangulation stations are usually found on the highest point of a hill
or a mountain. In areas of little relief, the stations may be located at
prominent points or sites where a tower could have been easily
erected.
* BMsandtraverse stations are typically located along roads, railroads,
pipelines, or other transportation routes, which permit intervisibility
and accessibility. BMs and traverse stations may also be found along
waterways, rivers, canals, and coastlines.
Available Information
3-4 Survey Recon
3-18. In some areas, urbanization has changed road or drainage patterns. In
rural areas, land may have been cleared and cultivated or fields may have
become overgrown or reforested. Gather and consider all available
information when searching for a station.
FM 3-34.331
3-19. Trig lists, control cards, and control bulletins contain brief descriptions
and sketches of stations. The information may be outdated or insufficient for a
final product but will permit surveyors to locate the general vicinity of the
station. The final steps in locating the station will involve the use of distances
and azimuths from the reference marks (RMs) to the station.
3-20. Previous survey data may include survey schemes, overlays, or plots
depicting the relative position of the stations in the general area. After one or
more stations have been recovered, the other stations may be roughly plotted
and located using a magnetic compass and either intersection or resection
methods.
3-21. Aerial photographs may be used if the station to be recovered can be
identified on the photographs. Using features that are permanent and
prominent on both the photograph and the ground will permit surveyors to
reach the station site
3-22. Maps with the plotted coordinates of the station will permit surveyors to
identify the route of travel to the station. Maps will also assist surveyors in
determining the station’s accessibility.
3-23. Local information sources include local surveyors, public-service
officials, construction companies, and landowners. Local sources may be the
only means of locating a station if the area has dramatically changed since the
other sources of information were published.
Station Verification
3-24. Verification of a station must be performed before using the station.
Where only one other station is intervisible, a check-distance measurement
can be performed using the GPS or a conventional method. Where two or more
stations are intervisible, check-angle observations or GPS measurements can
be performed. After the measurements and observations have been performed
and reduced, they will be compared to the published information. If the
results agree within the overall specifications for the survey project, the
stations may be used.
SELECTION OF NEWSTATION SITES
Considerations
3-25. New station sites will be selected after all existing stations have been
recovered, described, and verified. The new stations will be placed where
required to complete the scheme of the survey.
3-26. Correct selection of a new station site will save time and expense and
will prolong the life of the new station. Consider the following paragraphs
when selecting a new station site.
3-27. Permanency. Monuments (also referred to as marks or markers) can
be permanent or temporary.
* Permanent monuments. Permanent monuments are set in a
relatively stable material or structure for the purpose of preserving
the location of either horizontal or vertical control. Consider another
Survey Recon 3-5
FM 3-34.331
3-6 Survey Recon
site if the proposed site may experience disturbance or land
development. Sincethere are a wide variety of possible situations that
may be encountered when setting a monument, it is impossible to
address them all. The ultimate selection of the site is at the discretion
of the monument setter.
* Temporary markers. Temporary markers are the same as
permanent monuments except that the preservation time required is
less. Temporary markers shall consist of a 1- by 2-inch wooden hub (or
larger) with adjacent guard stakes, a copper nail and washer, or a
temporary spike that is set in relatively stable material.
3-28. Security. Foremost on the list of considerations is a monument's
susceptibility to damage or destruction. It is necessary to anticipate any
construction that might occur in the area. Frequently, marks that are set in
asphalt surfaces are paved over periodically. Marks that are set off the edge of
the asphalt surface will stand a better chance of survival.
3-29. Accessibility. Accessibility of the marks should be evaluated in
selecting the site. If the mark cannot be found or conveniently occupied, its
worth is questionable. Determine if there are nearby objects that can be used
as references. Distances and directions from prominent reference objects are
used to locate a mark. These distances and directions are referred to as lines
of position (LOPs). The prominent objects are referred to as origins. At least
two LOPs are required to describe a point. The closer to perpendicular that
the angle at which the LOPs intersect, the more accurate a position can be
described.
3-30. Stability. All marks are subject to the effects of geologic and soil
activity. Vertical-control marks or BMs are particularly vulnerable because
this activity results in vertical movements much more than horizontal motion.
Selecting advantageous topographic features (such as the crests of hills) will
increase soil stability and decrease frost heave and the consistency of the soil
will tend to be more firm. Also consider the soil-grain size, and when possible,
choose a site with coarse-grained soils. Fined-grained soils (such as days) are
susceptible to high moisture content, which can be affected by frost and
erosion.
3-31. Safety. |f a mark extends below the ground, there is a chance of
encountering underground cables or pipes during installation. Evidence of
underground utility lines can often be observed at the surface. Waterlines are
marked by valve boxes, and in structures newer than 1960, the utilities are
likely to be buried. Avoid digging near light poles, phone lines, or electric and
gas junction boxes.
3-32. Visibility. Select sites that provide maximum visibility above the
horizon, plus 15*. Any obstruction above 15? will potentially block satellite
signals. The ideal site should have visibility in all directions above 15°;
however, in some locations at specific times, an obstruction in one or two
directions may not affect the ability to use the site for GPS surveying.
Existing BMs should be used as GPS monuments as often as possible. New
marks should be located as close as possible to a known vertical control.
Maximum effort should be made to locate all GPS-type monuments within
100 feet of easy access to ground transportation.
Station Names
FM 3-34.331
3-33. Names will normally be assigned by the customer (for example, the
project name or number followed by the sequence number of that station in
the scheme-of-control extension). Names should be an alphanumeric symbol
that is stamped on the respective disk marker. The name that appears on the
control point for publication purposes should be the same as the name that
actually appears on the mark. Old stations that are reestablished will be
given the previous name with a numerical suffix added (such as Boulder
number 2). In the absence of guidance from the customer —
e Usethe name of a nearby geographical feature.
e Use short names (maximum of 25 characters, including spaces).
* [Include the name of the agency or unit that set the mark if it is not
precast.
e Makesurethe station name is spelled correctly on all documents.
e Do not use special characters such as periods, commas, slashes, or
equal signs.
e Donot include nondescriptive terms such as spike or nail or personal
names.
Landowner Permission
3-34. Permission must be obtained before conducting a survey on any private
land. The survey-section sergeant or the party chief, working through the
local J udge Advocate General (J AG), will contact and negotiate with
landowners for access to prospective station sites. Written permission to enter
the land is preferred because it is documented. The local J AG will assist in
this matter and will help keep the military out of potential trouble.
3-35. US. The recon and survey parties should have a right-of-entry letter to
the overall area from their HQ. This letter does not entitle the survey team to
access private property or restricted areas without further permission. When
the landowner is contacted, a full explanation of the work to be done is given
without any attempt to conceal any inconveniences or damage that may arise.
Government regulations concerning damage claims should be explained when
necessary. |n the case of an absentee owner, who cannot be reached in person,
a letter explaining the work and asking consent to access the property should
be mailed.
3-36. Other Nations. When working in other nations, the appropriate officer
of the US embassy within that country will generally negotiate the right-of-
entry letters for overall areas within that country. However, a right-of-entry
letter or approval from the host nation is not always sufficient for access to all
public lands within the national boundaries. It is sometimes necessary to
contact the local officials where the work is to be performed. Agreements will
be conducted according to local customs. Some countries consider an oral
agreement, or any statement that could be construed to be an oral agreement,
to be contractual and binding. Any transfer of assets (material or otherwise)
require close coordination with the] AG.
Survey Recon 3-7
FM 3-34.331
MONUMENTATION
3-37. The setting of stations should be accomplished during the recon phase.
The selection of the monument type is based on local site conditions. The types
of marks to be used for vertical and horizontal control are a function of the
order and accuracy of the survey, the intended use of the data collected, and
the site conditions.
Surface Station Marks
3-38. A variety of standard monuments (described below) are currently
available for use as surface station marks. On projects conducted for NIMA or
the USACE, standard NIMA or USACE disks should be used. The disks are
set in the top of a concrete post or another appropriate monument. Each
survey method has individually designated disks. These station marks must
be as permanent as possible, intelligently placed for present and future use,
and safe from damage. In cultivated fields or in pastures (which may later be
cultivated), the owner’s permission should be obtained to build rock cairns or
to set guard or witness posts around monuments.
Subsurface Station Marks
3-39. Subsurface station marks are used for first-, second-, and third-order
stations. Pipe, rebar, and sectional rods are considered subsurface marks and
aid in the relocation of disturbed marks. Where bedrock is exposed and a
Type C monument is used, no such mark is feasible, and the drill hole itself is
sufficient.
Monument Types
3-8 Survey Recon
3-40. The type of monument used depends on the terrain, the climate, and the
soil composition. Engineer manual (EM) 1110-1-1002 identifies specifications
for survey markers and monuments. Monuments can be subdivided into two
general categories—standard and nonstandard.
3-41. Standard Monuments. Standard monuments use some form of
standard survey disk. These disks may be brass, bronze, aluminum, or other
alloys. Tables 3-1 and 3-2 suggest the type of monument to be used according
to required vertical and horizontal accuracy (USACE standards). A TypeG
monument is sufficient for all third-order surveys, both vertical and
horizontal.
Table 3-1. Site Conditions and Monument Types for Vertical Control
Monument Type
Site Condition Order of Accuracy
1 2 3
Rock outcrops and concrete structures C C C
Sand, gravel, till, silt, and clay A A G
Construction fill (disturbed earth) A A A
FM 3-34.331
Table 3-2. Site Conditions and Monument Types for Horizontal
Control
Monument Type
Site Condition Order of Accuracy
1 2 3
Rock outcrops and concrete structures C C C
Sand, gravel, till, silt, and clay G G G
Construction fill (disturbed earth) G G G
TypeG monument. This dassic, standard monument is made
completely of poured concrete with a disk set in the top of the concrete
(Figure 3-1, page 3-10). These procedures and dimensions are for a
second- or higher-order monument. A Type G monument is
constructed by excavating a hole that is 15 centimeters in diameter
and 60 centimeters deep. In areas where the maximum frost depth is
greater than 60 centimeters, the hole should be 30 centimeters below
the frost depth. The disk should be driven onto a pipe, a rod, or a
number 5 rebar that is 120 centimeters long. The pipe, rod, or rebar
assembly is then driven into the center of the hole until the top is
slightly above the surface. The holeis then filled with concrete, which
must not cover the disk. The use of pipe, rod, or rebar is optional. The
disk may be pushed directly into the fresh concrete, but a magnet
must be placed in the concrete if the bar is omitted.
Type C monument. Sound bedrock is the most desirable location for
a BM, as illustrated by Figure 3-2, page 3-10. It provides the most
stable setting in terms of underground activity and potential
disturbances. Always use bedrock when a suitable outcrop exists. Use
a star drill to make a hole about 2.5 centimeters wide and 6
centimeters deep to receive the shank of the marker. Fill the hole with
epoxy resin and insert the disk, with the resin slightly built up around
the edge. When a solid bench or ledge is covered with a few feet of top
soil, the subsurface mark should be in the ledge and a concrete
monument should be set above it to protrude above the surface.
Type A monument. Use a TypeA rod monument (Figure 3-3,
page 3-11) when sound bedrock or substantially stable structures are
not available. The monument provides the extra horizontal stability
required for 3D surveys, which makes the monument a suitable GPS
mark. Refer to EM 1110-1-1002 for details on installing а Type A
monument.
NOTE: Туре A monuments are used in marshes. Туре С
monuments are used in permafrost areas.
Precast monument. To eliminate the need for mixing and pouring
monuments at the site, precast monuments may be used if the project
specifications permit. These precast monuments are fabricated at the
base station or camp and are constructed with the equivalent
dimensions listed for poured concrete. If a subsurface mark is
Survey Recon 3-9
FM 3-34.331
Standard USACE
survey disk
NS
In-situ soil
E
©
©
8 §
o
5E
Q-=
с Е
=
о Е
оо
©
{айд сә]
no
o
_
LL
S
Concrete
Pipe, rod, or rebar
(optional) >
Figure 3-1. Type G Monument
Countersink disk flush
with surface
Rock or е
concrete = Epoxy grout
ty
3T
i
E
| Drill a hole that is
ЕРЕ nt
ШЕ ГТ
2.5 cm in diameter.
Figure 3-2. Type C Monument
3-10 Survey Recon
FM 3-34.331
Access cover
Ground
Survey disk
Finned rod section
Concrete
15-cm PVC pipe
2-cm rod
Eon EO | Aluminum rod section
p р a driven to refusal
Figure 3-3. Type A Monument
required, it is placed as identified above with a carefully plumbed
precast monument.
e Commercial monuments. A number of commercial monuments are
available that can be considered standard monuments. These are
generally metal or plastic rods (with a disk affixed to the top) that are
driven into the ground.
e RMs.RMs are usually set in the same type of monument as the main
station, but they can be made smaller. The number of RMs used
depends on the survey method. In triangulation and traverse
methods, at least two, but normally three, RMs will be set for each
station. These marks should be located within 30 meters of the station
and at intervals of about 120? around the station. No subsurface
marks are used with these marks. RMs should be located where they
are least likely to be disturbed and where direct measurements can be
made to them from the station. It is permissible to use drill holes or
chiseled marks in rock outcrops.
¢ Azimuth marks. Azimuth marks are established in connection with
SCPs to furnish an azimuth that will be available to local surveyors
from an ordinary ground-level instrument setup. These marks are
used in the extension of control from the station. The readings to
azimuth marks are observed as part of the traverse method. Azimuth
marks are permanent monuments that are placed in a prominent and
safe location and more than 400 meters but less than 3 kilometers
from the triangulation station. Prominent, permanent man-made
Survey Recon 3-11
FM 3-34.331
structures may also be used as azimuth marks (for example, the light
on the top of a water or radio-station tower or the cross on a church in
a nearby town).
3-42. Nonstandard Monuments. These monuments can take many forms
and, if properly installed, provide for a good, permanent control station. Some
examples are—
e Expended shell casings (7.62 to 105 millimeters) embedded into а
concrete post as prepared for standard monuments.
e Sections of rebar or pipe driven into the ground with a concrete collar
poured around the upper 0.3 meter.
To aid in the preservation and to serve as a means of easy recovery of
monuments, a witness and/or guard post may be established. Witness and
guard posts are marked to be readily seen and identified.
* Witness post. A witness post is a sign or stake driven into the ground
next tothe station or RM.
* Guard post. A guard post is emplaced around a station that is
susceptible to damage from ground traffic. They are generally large
wood stock (8 inches by 12 inches by 8 feet) or expended steel (such as
sections of railroad rails or heavy pipe). They are usually set 1 to
1.5 meters into the ground and secured with concrete.
STATION DESCRIPTION AND SKETCH
Recovery Notes
3-12 Survey Recon
3-43. The recon party will prepare a description and sketch of all newly
established permanent and temporary stations and all stations recovered.
Stations recovered, but not used, must also have a description completed. The
description and sketch will be done on DA Form 1959 (Figure3-4) or in an
appropriate field book. The field record is done in free hand using vertical
gothic lettering. A final DA Form 1959 should be typed and kept with the
official records.
3-44. Provide a narrative report (compiled at the station site) containing all
the information necessary to expeditiously locate the station. The description
should enable someone totally unfamiliar with the area to go, with certainty,
to the immediate vicinity of the station. In conjunction with a sketch, a
positive identification of the station and RMs should be possible. Avoid
repetition where possible. The description should be brief (to the point),
logical, and includethe following information.
3-45. The authorized recovery notes are as follows:
* New station. This is a newly established station for which no
description exists.
e Recovered as described. This is a station that is recovered exactly
as described. All marks are in good condition, the distances and
directions are verified, and the sketch and description are adequate.
The statement alone is sufficient for the recon recovery card.
Transcribe the old sketch and description onto the new control card.
FM 3-34.331
TYPE OF MARK STATION
Germany 170 Monument Stone Kamp
LOCALITY STAMPING ON MARK AGENCY (CAST IN MARKS) ELEVATION (T
Illesheim/L6528 NA NA 331.671 (м)
LATITUDE LONGITUDE
49°28'10.47467" 10°23'10.92519"
(NORTHING) (EASTING) PAT | EASTING) (NOR THING) GRID AND ZONE ESTABLISHED BY (AGENCY)
5,480,852.200 (м) 600,444.268 (M) 32U 320th Engineer
(NORTHING} {EASTING) (EASTING) (NORTHING) (FT) |GRID AND ZONE DATE (YYYYMMDD) | | ORDER
(M) 2001 07 15 |Third
GRID AZIMUTH, ADD о i ki TO THE GEODETIC AZIMUTH
GRID AZ. (ADD) (SUB.) о * Ы TO THE GEODETIC AZIMUTH
AZIMUTH OR DIRECTION
GEOD. DISTANCE GRID. DISTANCE
OBJECT
| omm | Miu. Copa d (METERS) FRETI (METERS) FEET)
The station is located on Storch Barracks, Illesheim, Germany.
To reach the station front gate of Storch Barracks (Grid 0082) go straight for
0.1 mile to four-way intersection. Turn right (west) and proceed 0.8 mile to the gate
of the access road and a guard shack. Follow the access road around the
perimeter of the airfield for 0.9 mile to the station site.
The station is a Type 70 monument protruding 20 cm above the ground and is
located atop a burm.
The station is located 75.1 m at an azimuth of 160° from Building 6680, 82.3 m
from the hot fuel point and 67 m from the fuel point sign.
Horizontal position was established by third-order class | traverse.
Elevation was established by third-order leveling procedures.
DA FORM 1959, JUL 2001 REPLACES DA FORMS 1959 DESCRIPTION OR RECOVERY OF HORIZONTAL CONTROL STATION
AND 1960, 1 FEB 57, WHICH For use of this form, see FM 3-34.331; the proponent USAPA V1.00:
ARE OBSOLETE. agency is TRADOC.
Figure 3-4. Sample of DA Form 1959
Survey Recon 3-13
FM 3-34.331
General Location
e Recovered. This is a recovered station with changes that make the
old sketch and description inaccurate or inadequate. Complete a new
card and make a new sketch and/or description of the station. Report
any alterations to the station or RMs and describe the altered marks
and new measurements of the referenced distances and directions. An
effort should be made to improve all sketches and descriptions.
* Not recovered. This is a station for which no positive evidence of
existence can be found after a diligent search has been made.
e Destroyed. This is a station at which there is positive evidence that
the station did exist, but the station and its RMs have been so
mutilated that it cannot be replaced within 1 centimeter of its original
position. The individual making the recovery and writing the
description must use judgment in determining the status of a station.
A station may be destroyed for precise purposes but still be valuable
for surveys requiring less accurate control (for example, gravimetric,
magnetic, or astronomic surveys).
* Reset. This is a station at which the monument and/or station marks
have been replaced so that the mark is within 1 centimeter of its
original position. A station is reset only from subsurface and/or RMs
that have not been moved from their original positions. The task of
resetting monuments may be assigned to the recon party.
* Disturbed. This notation is generally used only with reference to
vertical control points. It is a station at which the monument is
physically present, but it has been so moved that it has lost its value
as a vertical control point within the accuracy to which it was
originally established.
3-46. This information follows the recovery note. It identifies the location of
the station area on a map in relation to cities and towns, bridges, and other
major landmarks. The political subdivision should also be stated.
Route Description
3-47. This describes the route to the station site. The description should start
from an easily located point such as a public building, a park, a main-road
intersection, or any other permanent landmark that is identifiable both on the
map and on the ground. Distances between check points on the route are given
in miles and tenths of miles or kilometers and meters. Changes in route
direction are given as both left or right and east (E), west (W), north (N), or
south (S).
Station-Site Description
3-14 Survey Recon
3-48. Describe the exact location of the mark in relation to readily identifiable
RMs. List the magnetic azimuth and the distance from the reference point to
the station mark.
FM 3-34.331
Station-Mark Description
RMs
Azimuth Mark
3-49. Describe the actual mark (for example, drill hole, bronze disk, or
chiseled mark in stone) and the exact stamping on the mark (agency, year,
and type of station). Note if the station mark is above or below the ground's
surface.
3-50. Describe RMs in the same manner as the station mark. Include the
distances and directions measured from the station mark.
3-51. Describethe azimuth mark in the same manner as RMs. The distanceis
usually approximated rather than measured.
View From Tripod Height
3-52. Describe the field of view from tripod height. For example, the view is
unobstructed in all directions except south and the trees (60 feet high,
300 feet from the station) obstruct the view between the magnetic azimuths of
170? and 215*.
Miscellaneous Information
Sketch
3-53. List any important information about the station site (which is not
covered elsewhere) in the notes at the bottom of the description. This may
include a photo number and mission (if applicable), danger areas, or access
concerns.
3-54. The sketch should be clear and simple and contain only enough detail
for positive identification of the station. In general, it should contain the—
e Features of a permanent nature. Show the features around the
station with enough detail so that they will not be confused with other
similar features. For example, many road intersections and hilltops
look alike. Extend the sketch slightly so that the characteristic
features become evident. When there is little detail available make a
rough contour sketch. Use only standard topographic and military
symbols on the sketches.
* Scope and scale. J udgments on what features are actually required
to identify the station and the individual's ability to draw will usually
govern the scope of a sketch. Normally, a sketch should include the
area within a radius of 200 feet to 1/2 mile. Avoid sketches that cover
an area of several miles. In all cases, the termination point of the to-
reach site must be on the sketch. The sketch does not need to be
drawn to scale.
* Orientation. The sketch must be oriented to the north.
DA Form 1959 has a preprinted arrow to indicate the direction.
Survey Recon 3-15
FM 3-34.331
TRANSPORTATION
3-55. The recon party will use transportation that is organic to the unit
according to the unit's TOE and SOPs. When available, due to project
requirements or customer support, using aircraft will enhance the project
recon. Helicopters can greatly assist and speed recon efforts (for example,
checking routes of travel and lines of sight between stations, selecting and
identifying stations, and determining the scheme for extending surveying
control). If aircraft are used, it is mandatory that the pilots be thoroughly
briefed on the survey project. Complete knowledge of the entire project by the
pilots will expedite the field recon and accelerate the progress of the project.
COMMUNICATION
LOGISTICS
3-56. The recon party has access to radios, according to the unit's TOE and
SOPs. Surveyors use the radios to confirm lines of sight when stations are
separated by great distances. Before using the radios on a survey project, the
party chief will obtain authorized frequencies from the local (customer's)
signal officer. Surveyors will use the radios according to local CEOI and
communi cations-electronics standing instruction (CESI). Surveyors will also
follow the unit's standing signal instructions (SSI), signal operation
instructions (SOI), and radio-communications procedures. In the event of a
conflict, the procedures of the local signal office will take precedence.
3-57. The party chief will make arrangements with the customer to ensure
that both fuel and maintenance are available for all vehicles. He will also
ensure that adequate space is available to secure equipment and to perform
project administration and field-office computing.
RECON REPORTS
3-16 Survey Recon
3-58. Upon completion of the field recon, the party chief will submit a recon
report. If the area or the project is large, the project will be divided into phases
and a report will be prepared at the completion of each phase. The recon
report is discussed in detail in Chapter 11.
Chapter 4
Datums, Grids, and Coordinate References
The discipline of surveying consists of locating points of interest on the
surface of the earth. Points of interest are defined by spherical or planar
coordinate values that are referenced to a defined mathematical figure. In
surveying, the figure may be an equipotential surface, an ellipsoid of
revolution, or a plane.
DATUMS
GEOID
ELLIPSOID
PROJ ECTIONS
4-1. The earth is an ellipsoid, not a sphere, flattened slightly at the poles and
bulging somewhat at the equator. Datums are reference surfaces that
consider the curvature of the earth for the mathematical reduction of geodetic
and cartographic data.
4-2. The geoid is the equipotential surface within or around the earth where
the plumb line is perpendicular to each point on the surface. The geoid is
considered a MSL surface that is extended continuously through the
continents. The geoidal surface is irregular due to mass excesses and
deficiencies within the earth. The figure of the earth is considered as a sea-
level surface that extends continuously through the continents. The geoid
(which is obtained from observed deflections of the vertical) is the reference
surface for astronomical observations and geodetic leveling. The geoidal
surfaceis the reference system for orthometric heights.
4-3. The WGS is not referenced to a single datum point. It represents an
ellipsoid whose placement, orientation, and dimensions "best fit" the earth's
equipotential surface that coincides with the geoid. The system was developed
from a worldwide distribution of terrestrial gravity measurements and
geodetic satellite observations. Several different ellipsoids have been used in
conjunction with the WGS ellipsoid. Several ellipsoids are used in US military
mapping. The goal is to eventually refer all positions to the WGS, which has a
specific set of defining parameters, or to a WGS-compatible ellipsoid.
Ellipsoids may be defined by a combination of algebraically related
dimensions such as the semimajor and semiminor axes or the semimajor axis
and the flattening. Figure 4-1, page 4-2, illustrates the defining parameters of
some ellipsoids used by NIMA.
4-4. A map projection is the systematic drawing of lines representing the
meridians and parallels (the graticule) on a flat surface. Different projections
Datums, Grids, and Coordinate References 4-1
FM 3-34.331
Ellipsoid
Airy 6,377,563.396 6,356,256.910
Australian national 6,378,160 298.25
Bessel 6,377,397.155 299.1528128
Clarke 1866 6,378,206.4 6,356,583.8
Clarke 1880 6,378,249.145 293.465
Everest 6,377,276.345 300.8017
Hough 6,378,270 297
International 6,378,388 297
Modified Airy 6,377,340.189
Modified Everest 6,377,304.063 300.8017
South American 1969 6,378,160 298.25
WGS 72 6,378,135 298.26
*Flattening is the ratio of the difference between the semimajor axis and the semiminor axis of the
(a- b)
a
spheroid and its major axis and may be stated by the numerical value of the reciprocal of the
flattening (1/f).
Figure 4-1. Defining Parameters of Ellipsoids
have unique characteristics and serve differing purposes. Projecting the
graticule of the ellipsoid onto a plane depicts the projections. The intersections
of the graticule are computed in terms of the ellipsoid.
4-2 Datums, Grids, and Coordinate References
GRIDS
FM 3-34.331
4-5. US military maps use the sexagesimal system of angular measurement
(the division of a full circle into 360?) for designating the values of the
graticule. A degree is divided into 60 minutes, and each minute is divided into
60 seconds. Parallels are numbered north and south from 0? at the equator to
90? at the poles. Meridians are numbered east and west from 0? at the prime
meridian to a common 180? meridian. The prime meridian used for US
military mapping and charting coincides with the Bureau International de
l'Heure defined as zero meridian, located near Greenwich, England.
4-6. The projections used as the framework of all US military maps and
charts are all conformal. Conformability indicates that small areas retain
their true shape; angles closely approximate their true values; and, at any
point, the scale is the same in all directions. The following projections, which
show military grids, are prescribed for US military topographic mapping and
charting:
e Maps at scales larger than 1:500,000 for areas between 80° south and
84? north are based on the Universal Transverse Mercator (UTM)
Projection.
e Maps of the polar regions (south of 80° and north of 84°) are based on
the Universal Polar Stereographic (UPS) Projection.
These projections are being replaced by the WGS and will be phased out once
the maps have been reprinted with the WGS.
4-7. The Mercator projection is not normally used for military topographic
maps; however, its description serves as a basis for understanding the
transverse Mercator projection. The Mercator projection can be visualized as a
spheroid projected onto a cylinder tangent to the equator and parallel to the
polar axis (Figure 4-2, page 4-4). When the cylinder is opened and flattened, a
distortion appears. The distortion becomes more pronounced as the distance
from the equator increases. The Mercator projection is transversed by rotating
the cylinder again until the spheroid is parallel to a second axis (the
meridian), which is then open and flattened (Figure 4-3, page 4-5). For
military purposes and to minimize distortion, the transverse Mercator
projection uses 60 longitudinal zones, each 6? wide.
4-8. Most military operations assume that map and ground distances are
equivalent. However, in certain geodetic and artillery operations, where long
distances are involved and the accuracy of results is essential, it is necessary
to correct for the difference between distances on the map and distances on
the ground. This is done by using scale factors from prepared tables or
formulas. For the transverse Mercator projection, the scale factor is 1.00000
(unity) at the lines between each zone, decreasing inwardly to 0.9996 at the
central meridian (CM) and increasing outwardly to about 1.0010 near the
zone boundaries at the equator.
4-9. Grids are applied to maps to provide a rectangular system for referencing
and making measurements. There is a definite relationship between the grid
and the graticule, so that a corresponding geographic position can be
determined for each grid position. Military grids consist of parallel lines
Datums, Grids, and Coordinate References 4-3
FM 3-34.331
Development
surface (cylinder)
Origin of projecting lines
(3/4 of the way back
Spheroid and cylinder on i along the diameter).
common axis and tangent и
along the equator.
z Lu
nr
180 17 paar ee |0* 730" (CU Ast и ы* G^ Р оэ aT wr SE" 90" dp te as БНР ee qe
Flattened cylinder with developed projection.
Figure 4-2. Mercator Projection
4-4 Datums, Grids, and Coordinate References
FM 3-34.331
Axis of spheroid normal to
axis of cylinder; spheroid
tangent to cylinder along a
meridian.
Development surface
(cylinder)
Origin of projecting lines
(3/4 of the way back along
the diameter).
WT ws
ART Rn ud
FERE,
| кр? |
LECT
САУ
СК
РАНЫ.
Figure 4-3. Transverse Mercator Projection
Datums, Grids, and Coordinate References 4-5
FM 3-34.331
intersecting at right angles and forming a regular series of squares. The
north-south lines are called eastings and the east-west lines are called
northings. Each grid line is one of an even-interval selection of measurement
units. The interval is selected according to the map scale. The military prefer
to use the UTM grid for areas between 80? south and 84? north.
COORDINATE REFERENCES
4-10. Coordinates may be transformed from one grid system to another (for
example, between the Lambert grid and the UTM grid or between different
grid zones). The preferred method is to transform the grid coordinates from
the first grid system to geographic positions. Then transform the geographic
positions to the grid coordinates of the second grid system. This method does
not change the datum.
THE US MILITARY GRID-REFERENCE SYSTEM
4-11. The US Military Grid-Reference System (MGRS) is designed for use
with UTM grids. For convenience, the earth is generally divided into 6? by 8?
geographic areas, each of which is given a unique grid-zone designation. These
areas are covered by a pattern of 100,000-meter squares. Two letters (called
the 100,000-meter-square letter identification) identify each square. This
identification is unique within the area covered by the grid-zone designation.
4-12. The MGRS is an alphanumeric version of a numerical UTM grid
coordinate. Thus, for that portion of the world wherethe UTM grid is specified
(80? south to 84? north), the UTM grid-zone number is the first element of a
military grid reference. This number sets the zone longitude limits. The next
element is a letter that designates a latitude bond. Beginning at 80? south and
proceeding northward, 20 bands are lettered C through X. In the UTM portion
of the MGRS, the first three characters designate one of the areas within the
zone dimensions.
4-13. A reference that is keyed to a gridded map (of any scale) is made by
giving the 100,000-meter-square letter identification together with the
numerical location. Numerical references within the 100,000-meter square
are given to the desired accuracy in terms of the easting and northing grid
coordinates for the point.
4-14. The final MGRS position coordinate consists of a group of letters and
numbers that include the following elements:
* The grid-zone designation.
• Тһе 100,000-meter-square letter identification.
* The grid coordinates (also referred to as rectangular coordinates) of
the numerical portion of the reference, expressed to a desired
refinement.
The reference is written as an entity without spaces, parentheses, dashes, or
decimal points. Examples are as follows:
• 185 (locating a point within the grid-zone designation).
e 18500 (locating a point within a 100,000-meter square).
e 18SUU80 (locating a point within a 10,000-meter square).
4-6 Datums, Grids, and Coordinate References
FM 3-34.331
e 185008401 (locating a point within a 1,000-meter square).
e 18500836014 (locating a point within a 100-meter square).
4-15. To satisfy special needs, a reference can be given to a 10-meter square
and a 1-meter square. E xamples are as follows:
• 850083630143 (locating a point within a 10-meter square).
e 18SUU 8362601432 (locating a point within a 1-meter square).
4-16. There is no zone number in the polar regions. A single letter designates
the semicircular area and the hemisphere. The letters A, B, Y, and Z are used
only in the polar regions, and their presence in an MGRS (with the omission of
a zone number) designates that the coordinates are UPS. An effort is being
made to reduce the complexity of grid reference systems by standardizing a
single, worldwide grid reference system (for example, WGS).
GEOGRAPHIC COORDINATES
4-17. The use of geographic coordinates as a system of reference is accepted
worldwide. It is based on the expression of position by latitude (parallels) and
longitude (meridians) in terms of arc (degrees, minutes, and seconds) referred
to the equator (north and south) and a prime meridian (east and west).
4-18. The degree of accuracy of a geographic reference (GEOREF) is
influenced by the map scale and the accuracy requirements for plotting and
scaling. Examples of GEOREFs are as follows:
e 40? № 132? E (referenced to degrees of latitude and longitude).
e 40?21' № 132°14 (referenced to minutes of latitude and longitude).
e 4072112" N 132?14'18" E (referenced to seconds of latitude and
longitude).
e Д40°21'12.4” N 132?14'17.77E (referenced to tenths of seconds of
latitude and longitude).
e 40?21'12.45" № 132?14'17.73" E (referenced to hundredths of seconds
of latitude and longitude).
4-19. US military maps and charts include a graticule (parallels and
meridians) for plotting and scaling geographic coordinates. Graticule values
are shown in the map margin. On maps and charts at scales of 1:250,000 and
larger, the graticule may be indicated in the map interior by lines or ticks at
prescribed intervals (for example, scale ticks and interval labeling at the
corners of 1:50,000 at 1' [in degrees, minutes, and seconds] and again
every 5’).
THE WORLD GEOREF SYSTEM
4-20. The World GEOREF System is used for position reporting. It is not a
military grid and, therefore, does not replace existing military grids. It is an
area-designation method used for interservice and interallied position
reporting for air-defense and strategic air operations. Positions are expressed
in a form that is suitable for reporting and plotting on any map or chart
(graduated in latitude and longitude) regardless of the map projection.
Datums, Grids, and Coordinate References 4-7
FM 3-34.331
4-21. The system divides the surface of the earth into quadrangles, the sides
of which are specific arc lengths of longitude and latitude. Each quadrangleis
identified by a simple systematic letter code giving positive identification with
norisk of ambiguity.
4-22. There are 24 longitudinal zones (each 15? wide) extending eastward
from the 180? meridian around the globe through 360? of longitude. These
zones are lettered from A to Z inclusive. There are 12 bands of latitude (each
15? high) extending northward from the south pole. These bands are lettered
from A toM inclusive, northward from the south pole.
4-23. Each 15? quadrangle is subdivided into 15, 1? zones of longitude
eastward from the western meridian of the quadrangle. These 1? units are
lettered from A to О inclusive. Each 15° quadrangle is also subdivided into 15,
1° bands of latitude northward from the southern parallel of the quadrangle.
These bands are lettered from A to Q inclusive. Four letters may now identify
a 1° quadrangle anywhere on the earth’s surface.
4-24. Each 1° quadrangle is divided into 60’ of longitude (numbered eastward
from its western meridian) and 60’ of latitude (numbered northward from its
southern parallel). This direction of numbering is used wherever the 1°
quadrangle is located. It does not vary, even though the location may be west
of the prime meridian or south of the equator. A unique reference for defining
the position of a point to an accuracy of 1' in latitude and longitude (for
example, 2 kilometers or less) is given by quoting four letters and four
numerals. The four letters identify the 1° quadrangle. The first two numerals
are the number of minutes of longitude. The last two numerals are the
number of minutes of latitude. If the number of minutes is less than 10, the
first numeral will be a zero (for example, 04).
4-25. Each of the 1? quadrangles may be further divided into decimal parts
(tenths or hundreths) eastward and northward. Thus, four letters and six
numerals will define a location to 0.1’ and four letters and eight numerals will
define a location to 0.01.
GPS REFERENCE SYSTEMS
4-26. Tofully understand GPS and the positional information, it is important
to understand the reference system on which it is based. GPS satellites are
referenced to the WGS-84 ellipsoid. The absolute positions that are obtained
directly from the GPS measurements are based on the 3D, earth-centered
WGS-84 ellipsoid. Coordinate outputs are on a Cartesian system (X, Y, and Z)
relative to an earth-centered, earth-fixed (ECEF) rectangular coordinate
system having the same origin as the WGS-84 ellipsoid (geocentric). WGS-84
Cartesian coordinates are then converted into WGS-84 ellipsoid coordinates
(latitude, longitude, and height). The GPS uses the WGS-84 ellipsoid for
geodetic survey purposes. The GPS routinely provides differential positional
results on the order of 1 part per million (ppm), compared to the accepted
results of 1:300,000 for NAD 83 and approximately 1:100,000 for NAD 27.
HORIZONTAL-POSITIONING DATUMS
4-27. One application of DGPS surveying is densifying project control.
Densification is usually done relative to an existing datum (NAD 27, NAD 83,
4-8 Datums, Grids, and Coordinate References
NAD 27
NAD 83
FM 3-34.331
or local). Even though GPS measurements are made relative to the WGS-84
ellipsoid coordinate system, coordinate differences (such as baseline vectors)
on this system can be used directly on any user datum. Minor variations
between these datums will be minimal when GPS data are adjusted to fit
between local datum stations. Such assumptions may not be valid when high-
order National Geodetic Reference System (NGRS) network densification is
being performed.
NOTE: NIMA provides datum transformation parameters to many
more datums (including local).
4-28. NAD 27 is a horizontal datum based on a comprehensive adjustment of
the US National Control Network of traverse and triangulation stations.
NAD 27 is a best fit for CONUS. The relative precision between initial-point
monuments of NAD 27 is by definition 1:100,000, but coordinates on any given
monument in the network contain errors of varying degrees. As a result,
relative accuracy between points on NAD 27 may be far less than 1:100,000.
4-29. NAD 83 uses many more station observations than NAD 27 to readjust
the US National Control Network. NAD 83 has an average precision of
1:300,000. NAD 83 is based on the Geodetic Reference System (GRS) of 1980
(GRS-80), earth-centered reference ellipsoid and, for most practical purposes,
is equivalent to WGS 84.
High-Accuracy Reference Networks Survey Datum
4-30. The nationwide horizontal reference network was redefined in 1983 and
readjusted in 1986 by the NGS. Since that time, several states and the NGS
have begun developing high-accuracy reference networks (HARN s) for
surveying, mapping, and related spatial-database projects. These networks
(developed exdusively with a GPS) are accurate to 1 part in 1,000,000.
ORTHOMETRIC ELEVATIONS
4-31. Orthometric elevations correspond to the earth's irregular geoidal
surface and are based on tidal fluctuations of the MSL at a specific location.
Measured DEs, based on spirit leveling, are generally relative to geoi dal
heights. The DEs between two points are called orthometric differences.
Orthometric heights for CONUS are generally referenced to NGVD 29 or
NAVD 88.
WGS-84 ELLIPSOID HEIGHTS
4-32. GPS-determined heights are referenced to an idealized mathematical
ellipsoid. This WGS-84 ellipsoid differs significantly from the geoid; thus, GPS
heights are not the same as orthometric heights. Due to significant variations
in the geoid (even over small distances), elevations cannot be directly equated
to orthometric differences. For small project areas where the geoid remains
fairly constant, the relationship between orthometric and ellipsoid heights can
be obtained from computer modeling or local geoid modeling. Local geoid
Datums, Grids, and Coordinate References 4-9
FM 3-34.331
modeling requires connecting to a sufficient number of existing orthometric
BMs from which the elevations of known points can be best fit by adjustment.
COORDINATE CONVERSION
4-33. Numerous mathematical techniques have been developed to convert
coordinates between NAD 83 and NAD 27. Thesetechniques include a variety
of multiple-parameter and multiple-regression transformation equations.
Each technique has advantages and disadvantages in terms of accuracy,
consistency, and complexity. To eliminate these inconsistencies, the USACE
Topographic Engineering Center (TEC) configured a comprehensive
coordinate-conversion software program called Corps Conversion (Corpscon).
Corpscon is the standard for topographic survey conversions, but newer
programs are available. Additional technical information and authorized
software programs can be obtained from TEC or NIMA web sites.
4-10 Datums, Grids, and Coordinate References
Chapter 5
Conventional Survey-Data Collection
Theodolites and transits are instruments designed to measure horizontal
and vertical angles. As optical instruments progressed, the devel opment of
optics allowed the telescope to become shortened to the point that the
optics could be rotated 360? horizontally. This act of turning the telescope
has sped up work and permitted the qualitative review of sighting and
instrument errors.
SECTION I - FUNDAMENTALS
5-1. Surveys are usually performed to collect data that can be drawn to scale
and plotted on a plan or map or to lay out dimensions shown on a design.
Measurements for both types of surveys must be referenced to a common base
for X, Y, and Z dimensions. The establishment of a base for horizontal and
vertical measurements is known as a control survey. Conventional control
surveys use two fundamental measurements—angle determination and
distance measurement.
ANGLE DETERMINATION
5-2. Horizontal angles are usually turned (or deflected) to the right or left.
The three types of angle measurements are as follows:
Interior angles. If angles in a dosed figure аге to be measured, the
interior angles are normally read. When all interior angles have been
recorded, the accuracy of the work can be determined by comparing
the sum of the abstracted angles with the computed value for the
closed loop (Figure 5-1, page 5-2).
Deflection angles. |n an open traverse (Figure 5-2, page 5-2), the
deflection angles are measured from the prolongation of the backsight
linetothe foresight line. The angles are measured either tothe left or
tothe right. The direction must be shown along with the numerical
value.
Vertical angles. Vertical angles can be referenced to a horizontal or
vertical line (Figure5-3, page 5-3). Optical-micrometer theodolites
measure vertical angles from the zenith (90° or 270° indicate a
horizontal line). Zenith and nadir are terms describing points on a
sphere. The zenith point is directly above the observer, and the nadir
point is directly below the observer. The observer, the zenith, and the
nadir are on the same vertical line.
Conventional Survey-Data Collection 5-1
FM 3-34.331
Station C
Station B
Station D
р Station А
4
Exterior angle =
Station E 272°55’
Figure 5-1. Interior Angles on a Closed Traverse
Е LO 17°Б1'В
22*18'R
LEGEND: 38°061.
L = left
R = right
Figure 5-2. Deflection Angles Shown on an Open Traverse
OPTICAL THEODOLITES
5-3. It is difficult to precisely set the angle values on the plates of an optical
theodolite. Angles are determined by reading the initial and the final
directions and then determining the angular difference between the two
directions. Optical theodolites are generally very precise. The optical
theodolite used by Army topographic surveyors (Figure 5-4, page 5-4) reads
directly to 1" and by estimation to 0.1”. Figure 5-4 shows that the micrometer
was turned to read an even 10”. This is done by moving the grid lines into
coincidence, and then the micrometer scale reading (02’44”) is added to the
circle reading (94°10’) to give the resulting angle of 94°12’44”. If several
sightings are required for precision purposes, distribute the initial settings
around the plate circle to minimize the effect of circle graduation distortions.
Table 5-1, pages 5-5 and 5-6, illustrates the circle settings for 2 through 16
positions for a 1" theodolite.
5-2 Conventional Survey-Data Collection
FM 3-34.331
Horizon Я Horizon
direction M US Ye. direction
Nadir angle
Nadir direction
Figure 5-3. Reference Directions for Vertical Angles (Horizontal, Zenith, and Nadir)
OBSERVATION PRECAUTIONS
5-4. Because of the high-accuracy requirements for second- and third-order
observations, constant precautions are necessary to counteract all error
sources. The party chief should periodically inspect the performance of all
observing parties. A good observer achieves the full potential of the
instrument at all times. Signals and targets should be precisely bisected. Very
little spread (three or fewer of the smallest increments marked on the
micrometer) between the direct and reverse measurements should be
consistently obtained. Proficiency can be attained only by a careful study of all
factors affecting the accuracy of theodolite observations. Efforts should be
made to eliminate all known error sources. Observation precautions are
summarized as follows:
* Instrument check. Check the instruments and targets for stability.
If an instrument is not stable, all other refinements are useless.
* Instrument adjustment. Pay careful attention to the parallax and
the indination of the horizontal circle plate. Errors introduced by the
parallax and the indination cannot be eliminated.
* Signal and target centering. Plumb signals and targets directly
over the SCP. Carefully aim signals and targets towards the observing
station.
5-5. Do not disturb the instrument while observing a position by releveling or
striking the instrument or its support. Avoid any lateral thrust to a clamp, a
Conventional Survey-Data Collection 5-3
FM 3-34.331
Microscope
Telescope
Reticle-illumination knob
focusing knob
Micrometer
Micrometer
assembly
Plate level
Inverter knob
Horizontal clamp
Spring housing
assembly
Optical plummet
Circular level
Spring housing
assembly
Collimation slow-
motion screw
Horizontal clamp knob
Horizontal-circle
drive cover
Horizontal-circle
drive knob
Tribrach locking
lever
2'40" 2'50"
nbn yy
Vertical angle = 94°12’44”
Figure 5-4. Optical Theodolite
5-4 Conventional Survey-Data Collection
FM 3-34.331
Table 5-1. Circle Settings for a 1" Theodolite
Number 5' Micrometer Drum 10' Micrometer Drum Circle Wild T-3 Micrometer
Two
1 NA NA NA 0? 00* 10” NA NA NA
2 NA NA NA 90° 05’ 40” NA NA NA
Four
1 0° 00’ 40” 0° 00’ 10” 0° 00’ 15”
2 45° 01’ 50” 45° 02’ 40” 45° 02’ 45”
3 90° 03’ 10^ 90? 05' 10” 90° 04’ 15”
4 135° 04’ 20” 135° 07’ 40” 135° 20’ 45”
Six
1 0° 00’ 10” 0° 00’ 10” 0° 00’ 15”
2 30° 01’ 50” 30° 01’ 50” 30° 02’ 35”
3 60° 03’ 30” 60° 03’ 30” 60° 00’ 50”
4 90° 00’ 10” 90° 05’ 10” 90° 04’ 15”
5 120° 01’ 50” 120° 06’ 50” 120° 00’ 35”
6 150° 03’ 30” 150° 08’ 30” 150° 20’ 50”
Eight
1 0° 00’ 40” 0° 00’ 10” 0° 00’ 10”
2 22° 01’ 50” 22° 01’ 25” 22° 00’ 25”
3 45° 03’ 10” 45° 02’ 40” 45° 02’ 35”
4 67° 04’ 20” 67° 03’ 55” 67° 00’ 50”
5 90° 00’ 40” 90° 05’ 10” 90° 04’ 10”
6 112° 01’ 50” 112° 06’ 25” 112° 00’ 25”
7 135° 03’ 10” 135° 07’ 40” 135° 20’ 35”
8 157° 04’ 20” 157° 08’ 55” 157° 00’ 50”
Twelve
1 0° 00’ 40” 0° 00’ 10” 0° 00’ 10”
2 15° 01’ 50” 15° 01’ 50” 15° 00’ 25”
3 30° 03’ 10” 30° 03’ 30” 30° 02’ 35”
4 45° 04’ 20” 45° 05’ 10” 45° 00’ 50”
5 60° 00’ 40” 60° 06’ 50” 60° 00’ 10”
6 75° 01’ 50” 75° 08’ 30” 75° 00’ 25”
7 90° 03’ 10” 90° 00’ 10” 90° 04’ 35”
8 105° 04’ 20” 105° 01’ 50” 105° 00’ 50”
9 120° 00’ 40” 120° 03’ 30” 120° 00’ 10”
10 135° 01’ 50” 135° 05’ 10” 135° 00’ 25”
11 150° 03’ 10” 150° 06’ 50” 150° 20’ 35”
12 165° 04’ 20” 165° 08’ 30” 165° 00’ 50”
Sixteen
1 0° 00’ 40” 0° 00’ 10” 0° 00’ 10^
2 11? 01’ 50” 11° 01’ 25” 11° 00’ 25”
3 22° 03’ 10” 22° 02’ 40” 22° 00’ 35”
4 33° 04’ 20” 33° 03’ 55” 33° 00’ 50”
5 45° 00’ 40” 45° 05’ 10” 45° 02’ 10”
6 56° 01’ 50” 56° 06’ 25” 56° 00’ 25”
7 67° 03’ 10” 67° 07’ 40” 67° 00’ 35”
8 78° 04’ 20” 78° 08’ 55” 78° 00’ 50”
Conventional Survey-Data Collection 5-5
FM 3-34.331
Table 5-1. Circle Settings for a 1” Theodolite (continued)
Number 5' Micrometer Drum 10' Micrometer Drum Circle Wild T-3 Micrometer
9 90? 00’ 40” 90° 00’ 10” 90° 04’ 10”
10 101° 01’ 50” 101° 01’ 25” 101° 00’ 25”
11 112° 03’ 10” 112° 02’ 40” 112° 00’ 35”
12 123° 04’ 20” 123° 03’ 55” 123° 00’ 50”
13 135° 00’ 40” 135° 05’ 10” 135° 02’ 10”
14 146° 01’ 50” 146° 06’ 25” 146° 00’ 25”
15 157° 03’ 10” 157° 07’ 40” 157° 00’ 35”
16 168° 04’ 20” 168° 08’ 55” 168° 00’ 50”
tangent screw, or the electric switch. Other operational precautions for
accurate observations are as follows:
e Repoint on the initial target after each circle setting.
e Check the plate level frequently.
e Protect the instrument from wind, sunshine, and precipitation.
5-6. When all other known precautions have been taken, one of the principal
causes of error is horizontal refraction. Sometimes elevating the signal will
reduce the effects of horizontal refraction, but often the only solution without
altering the traverse is to reobserve the target under different atmospheric
conditions.
HORIZONTAL-DIRECTION RECORDINGS
5-7. Procedures for recording horizontal directions are the same for all orders
of accuracy. Record horizontal directions on a DA Form 4253 (Figure 5-5) or
any authorized single-sheet recording forms. When operating the AISI, use
the appropriate recording media. In all cases, documentation should be
completed in the field. Each time an SCP is occupied, the following
information should be recorded:
e Instrument make, model, and serial number.
e Instrument operator's name.
e Recorder's name.
e Weather description.
= Temperature
= General atmospheric condition.
= Wind.
* Designation of the occupied station.
= Full station name.
* Year established.
= Мате of the agency on the disk.
5-8. The recording form should include the above information for each station
observed. If an instrument, signal, or target is set eccentric to a station (not
plumbed directly over the station mark), that item will be sketched on the
recording form. The sketch should include the distance and the directions that
the eccentric item is from the station. When intersection stations are
observed, the exact part of the point observed must be recorded and shown on
the sketch.
5-6 Conventional Survey-Data Collection
FM 3-34.331
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Conventional Survey-Data Collection 5-7
FM 3-34.331
5-9. Numbers and letters should be approximately half the height between
lines. The recording should be centered in the block and on the bottom line of
the block. All figures must be neat and legible. There should be no erasures or
obscuring of the original figures. Original numbers may be crossed out by
using a single diagonal line through the numbers. The corrected numbers
should be written above the original entry. The person making the correction
will initial above and tothe right of the original entry and within the block
and will explain the reason for the correction in the remarks column. No
position will be voided or rejected on any recording media, except in the case of
bumping the instrument or stand, which causes the instrument to become
unleveled. If the instrument is observed to be unleveled, make a note on the
recording media in the remarks column stating that the instrument was not
leveled and why. All recordings will be done with black ink. Directions will be
entered in the remarks column (in degrees, minutes, and seconds).
5-10. The observer will check every computation on each page or sheet. The
observer will verify the computation with a light, visible tick mark to the
upper right of the computed numbers or will correct the numbers as described
above. The observer will confirm that all computed numbers on the page have
been checked by initialing at the bottom right corner of the page.
5-11. If a recording book is used, make an index (on the appropriate page) of
the stations from which observations were made and recorded. An index is
also required for all other recording media, indicating where to locate
observations from any occupied SCP.
HORIZONTAL-DIRECTION ABSTRACTS
5-12. Second-order horizontal-observation specifications require that an
abstract of horizontal directions be compiled for every station at which
horizontal directions have been observed. DA Form 1916 (Figure 5-6) will be
compl eted before leaving the SCP. Third-order horizontal observations require
that the horizon closure, the corrected station angle, and the corrected
explement angle be recorded before leaving the SCP. Readings will be entered
opposite the proper circle position, as indicated in the field notes. The degrees
and minutes for each direction are entered one time at the top of each column,
and the seconds are entered for each circle position.
5-13. Record all observed positions on the DA Form 1916. If two or more
observations have been made for the same target, list all the observations in
the same box and determine the mean for that position.
5-14. Examine the listed positions. For any position that appears to vary
greatly from the apparent mean of all the positions, check the computations in
the field-recording book or other recording media. Be alert for a change in the
minutes of the computed directions (angles) in the field data. Reject any
positions that vary widely from the mean and then reobserve the positions.
Endose any values that are rejected by observation in parentheses and follow
with "Ro."
5-15. Compute the mean of the observed positions. Round the mean value of a
direction to the nearest 0.1" if a 1" instrument was used for observation.
Reject all observations that differ from the mean by more than the rejection
limit. Enclose any rejected observations in parentheses and follow with "R1."
5-8 Conventional Survey-Data Collection
FM 3-34.331
ABSTRACT OF HORIZONTAL DIRECTIONS
For use of this form, see FM 3-34.331; the proponent agency is TRADOC.
LOCATION ORGANIZATION STATION
Missouri 99th Eng Det (Survey) LAKE (USC&GS) 1932
OBSERVER DATE (YYYYMMDD) INST. (TYPE) (NO.)
SGT Smith 2001 04 02 Wild T-2 # 28234
POSTION: STATIONS OBSERVED
BROOK EXPLEMEN.
(USACE) TARY
1956 ANGLE
(Initial) ° t °
0° 00" 312 13
21.5
225
(36.0) Ro
21.0
21.5
22.0 à Mn Sta
EXPLEMEN-
21.5 . TARY
22.0
21.5 Я Closure
Error
Corrected
Mn Sta
EXPLEMEN. |
TARY
COMPUTED BY DATE (YYYYMMDD)| CHECKED BY DATE(YYYYMMDD)
SPC Sphar SSG J. Zambrano
2001 04 02 2001 04 02
DA FORM 1916, FEB 57 USAPA V1.01
Figure 5-6. Abstracting Horizontal Directions
R1 indicates that the value was rejected using the first mean value. The
rejection limit will be applied to each observation with the same amount of
accuracy as when the mean was determined.
5-16. Reobserve any rejected positions and determine a new mean. Reapply
the rejection limit. Enclose any positions still exceeding the rejection limit in
parentheses and follow with "R2." R2 indicates that the value was rejected
using the second mean value. Ensure that sufficient acceptable positions
remain.
Conventional Survey-Data Collection 5-9
FM 3-34.331
5-17. Оо пої reject any reading if it is within the rejection limits, unless it was
rejected at the time of observation. If a value was rejected at the time of
observation, check the field notes for the observer's reason for rejection. Once
a valueis rejected, it cannot be used again.
5-18. Do not use the mean of the readings if one of two or more readings on a
position is outside the rejection limits. Use only the reading that is within the
rejection limits. If two readings are outside the rejection limits (one is high,
the other is low, and the mean is within the limits), the readings must be
rejected. If there is a progressive change in the values of the positions of a
direction or if the mean of the first half of the positions differs appreciably
from the mean of the last half of the positions, attempt to observe another
complete set of positions before leaving the SCP.
VERTICAL-OBSERVATION RECORDINGS
5-19. Recording vertical observations (zenith distances [ZDs]) is the same for
all orders of accuracy. Vertical observations are recorded on DA Form 5817-R
(Figure 5-7), an authorized single-sheet recording form, or appropriate media
when operating the AISI. In all cases, complete documentation will be
performed in the field. In addition to the recording requirements, record the
following information:
e TheHl above the station (recorded to the nearest 0.01 meter).
* A sketch of the observed target (that shows the point observed on the
target) at the bottom of the object-observed column.
* The height of the observed target (HT) above the station being
observed (recorded to the nearest 0.01 meter).
* A sketch showing any target's adjoining stations. This sketch will be
drawn in the bottom of the remarks column. All possible points that
may be observed will be measured and recorded to the nearest
0.01 meter.
5-20. During vertical observations, thetime of the first observation of the first
position and the time of the last observation of the last position are recorded.
Thetimes are recorded to the nearest whole minute.
VERTICAL-OBSERVATION ABSTRACTS
5-21. Vertical observations are abstracted onto DA Form 1943 (Figure 5-8,
page 5-12) at the station site by the observing party. Targets or signals shown
to other stations are sketched and dimensioned at the bottom of the form. If a
target or signal is changed during the day, the time of the change and the new
dimensions are also entered.
5-22. Vertical observations recorded as vertical angles are converted to ZDs
before abstracting. The ZDs are abstracted, including the times of the
observations. The abstracted ZDs are meaned and reduced to corrected ZDs by
applying the reduction to line-joining stations. The following formula is used
to determine the reduction in seconds:
(HI — HT)sin mean ZD
Reduction in seconds — —
ssin1
where—
s =slope distance between stations (in kilometers)
5-10 Conventional Survey-Data Collection
FM 3-34.331
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Conventional Survey-Data Collection 5-11
FM 3-34.331
PROJECT
99E/99/TRA 3
ABSTRACT OF ZENITH DISTANCES
For use of this form, see FM 3-34.331; the proponent agency is TRADOC.
STATION
LAKE (USC&GS) 1932
INSTR. (TYPE) (NO.)
Wild T-2 452119
OBSERVER
SGT Smith
OBJECT
ABOVE
STATION
LOCATION
ORGANIZATION
99th Eng Det (Survey) NA
|
DIFF. OF
HEIGHTS
to
(Meters)
TELESCOPE
ABOVE
STATION
zt
(Meters)
REDUC-
TION TO
LINE
JOINING
STATIONS
OBSERVED ZENITH
DATE
DISTANCE
(YYYYMMDD) OBJECT OBSERVED
HOUR
= 0
(Meters)
HEIGHT OF STAND
CORRECTED ZENITH
DISTANCE
200107 15| 1425 BROOK 154 | 1.60 |-0.04 |-69.4 |90 04 475
т
1430 | (USACE) 1956 48.5
Observed center
90 04 48.0
of target
90 05 57.4
Slope distance = 8633.421 m
HEIGHT OF LIGHT* ABOVE
STATION
(Meters)
DATE
DATE
(YYYYMMDD)
(YYYYMMDD)
LIGHT SHOWN TO STATION LIGHT SHOWN TO STATION
HEIGHT OF LIGHT* ABOVE
STATION
(Meters)
2001 07 15 1.54 m at center
m
S
BROOK
(USACE 1956)
*Height of Light (or object above station) should also be entered on Abstract of Zenith Distances of station to which light was shown.
COMPUTED BY DATE (YYYYMMDD) |CHECKED BY
SPC Jones 2001 07 15 SGT Smith
DA FORM 1943, JUL 2001 EDITION OF FEB 57 IS OBSOLETE.
Figure 5-8. Abstracting Zenith Distances
5-12 Conventional Survey-Data Collection
DATE (YYYYMMDD)
2001 07 15
USAPA V1.00
FM 3-34.331
5-23. This formula will also be applied to the vertical observations performed
at the station at the other end of the observed line (reciprocal observations).
The total length of the lines is multiplied by 0.46 (a constant based on the
earth's curvature). Subtract 180? from the sum of the two corrected ZDs to
determine the observed difference expressed as minutes of arc. If the two
values differ by more than 1' of arc, perform a second set of reciprocal ZD
observations. Differences exceeding 1' of arc are normally due to errors in
observations or unusual refraction in the atmosphere (poor observing
conditions).
DISTANCE MEASUREMENT
5-24. The distance between two points can be horizontal, slope, or vertical. A
tape measure or an EDM device can measure horizontal and slope distances.
In surveying, horizontal-distance measurements are always required. A
distance measured on a slope can be trigonometrically converted to its
horizontal equivalent by using the slope angle or vertical DE. Figure5-9
illustrates a basic example of the geometry used to determine the horizontal
distance of a measurement over uneven ground.
Elevation at Station B = elevation at Station A + HI + V - HT
H(S cos o)
HI (measured)
Station A
Ground
LEGEND:
V = vertical distance
H = horizontal distance
S = slope distance
Station B
Figure 5-9. Geometry of an EDM (Basic Example)
OBSERVATION PRECAUTIONS
5-25. Distances measured using an EDME are subject to the same errors as
direction measuring equipment. The errors also include instrumental
component errors. Instrumental errors are usually described as a number of
millimeters plus a number of ppm. The accuracy of the infrared EDME AISI is
+(5 millimeters +5 ppm). The ppm accuracy factor can be thought of in terms
of millimeters per kilometer, as there are 1 million millimeters in 1 kilometer.
This means that 5 ppm equal 5 millimeters per kilometer. If the AISI is in the
D-bar mode, the accuracy is +(2 millimeters + 3 ppm). Errors introduced by
meteorological factors must be accounted for when measuring distances of
500 meters or more. Accurate ambient temperature and barometric pressure
Conventional Survey-Data Collection 5-13
FM 3-34.331
must be measured. An error of 1 degree Celsius (C) causes an error of 0.8 ppm
for infrared distances. An error of 3 millimeters of mercury causes an error of
0.9 ppm in distance.
INSTRUMENT CONSTANTS
5-26. Although manufacturers provide instrument and prism constants, it is
essential that instrument constants be verified under actual operating
conditions, especially for precise surveys. The following factors must be
considered:
* The use of a prism typically provides an indicated distance longer
than the true value. Applying a negative correction will compensate
for this effect. Each prism should have its own constant or correction
determined individually, and a master file should be maintained.
* An instrument constant can be either positive or negative and may
change due to the phase shifts in the circuitry. Therefore, a positive or
a negative correction may be required.
* The algebraic sum of the instrument and the prism constants are
referred to as the total constant. The correction for the total constant
(equal in magnitude but opposite in sign) is referred to as the total-
constants correction, from which the instrument or prism constant can
be computed if one or the other is known.
UTM SCALE FACTOR
5-27. The scale factor (a computed factor) affects the measured distance. The
scale factor for a particular UTM zone is solely dependent on the location of
the survey in relation to its east-west distance from the UTM-zone CM. These
zones are 6? wide and originate at 0° Greenwich meridian. North-south
distances within the zone have no influence on the scale factor. The scale
factor at the CM of UTM zones is 0.9996. The UTM scale factor toward the
east and west from the CM increases to approximately 1.0004. Data-reduction
procedures using the scale factor are necessary for precise surveys.
CURVATURE OF REFRACTION CORRECTION
5-28. Distance measurements are not on a straight line. The earth's
curvature and gravity affect the path traveled by the light beam. For a
measured distance of 1 kilometer, the beam changes its path by nearly
7 centimeters. An approximate estimate of this effect is expressed by the
following formula:
VD = 0.0675 km"
where—
VD —the vertical difference
0.0675 =the esti mated effect on the path traveled by light
km =thedistancein kilometers (for example, 0.9 or 1.2)
5-14 Conventional Survey-Data Collection
FM 3-34.331
EDME RECORDING
5-29. Distances measured by EDME will be recorded on authorized single-
sheet recording forms. Figure 5-10 shows a completed DA Form 5819. If the
AISI is used, the appropriate recording media is authorized.
FIELD SHEET, INFRARED
For use of this form, see FM 3-34.331; the proponent agency is TRADOC.
PROJECT
West RangeArtillery 3.79
ORGANIZATION
99th Engr Company
ZERO CORRECTION* CALIBRATION DATE
(YYYYMMDD)
-0.004 2001 07 15
INSTRUMENT STATION
Elkhorn (99th £ngy289|1.54. wv
ELEVATION
DATE (YYYYMMDD)
2001 07 15
APPROXIMATE DISTANCE
Ow
RECORDER
PFC White
OBSERVER
SPC Wilson
ELEVATION
INSTRUMENT
ECCENTRICITY*
TOWARD:
AWAY: 0.000 w
ECCENTRICITY*
TOWARD:
AWAY: 0.000 w
ZD INSTRUMENT TO REFLECTOR
INST. NO.
1268
PRISM. NO.
R-1268
METEOROLOGICAL READINGS
PRESSURE
(Hg)
MM.
DISTANCE (Meters)
1527
1527
1527
1527
1527
1527
1527
1527
1527
1527
15,273
TIME
INSTRUMENT | 0819
REFLECTOR| 0817
CORRECTION FACTOR (PPM)
PRODUCT = UD x PPM
RC = PRODUCT x 10-6
T =UD# 2+ RC
H’= (D? - (d)?
H’/=SIN ZDxT
HF t= H’x 3.280840
ж
762
761
1523
762
+5
MEAN UNGIR TE 2
1527.308 SLOPE^IST. N^ : (JD)
1527
ZERO ( ERECTION” (Z) o
PPM| +5
КОЕ RACTIVE INDEX
CORRECTION (RC) [0]
CORRECTED SLOPE
DISTANCE (T)
UNCORRECTED
HORIZON DISTANCE (H^)
PRODUCT 7636.540
RC. ^ 420.008
DIFF. OF ELEV. (d)
?Obtained from Instrument Calibration.
*Toward Eccentricity must be ADDED.
Away Eccentricity must be SUBTRACTED.
REMARKS
ECCENTRIC
CORRECTION* (EC)
HORIZON DISTANCE
(Ha) / (Нр)
COMPUTED BY
SSG Zambrano
CHECKED BY
SFC Gaw
DA FORM 5819, JUL 2001
DATE (YYYYMMDD)
2001 07 15
EDITION OF AUG 1989 IS OBSOLETE.
DATE (YYYYMMDD)
2001 07 15
of
USAPA V1.00
Figure 5-10. Recording Electronically Measured Distances
ELECTRONIC TOTAL STATIONS
5-30. Electronic theodolites operate in a manner similar to optical
instruments. Angle readings can be to 1" with precision to 0.5". Digital
readouts eliminate the uncertainty associated with reading and interpolating
Conventional Survey-Data Collection 5-15
FM 3-34.331
scale and micrometer data. The electronic angle-measurement system
eliminates the horizontal- and vertical-angle errors that normally occur in
conventional theodolites. Measurements are based on reading an integrated
signal over the surface of the electronic device that produces a mean angular
value and completely eliminates the inaccuracies from eccentricity and circle
graduation. These instruments also are equipped with a dual-axis
compensator, which automatically corrects both horizontal and vertical angles
for any deviation in the plumb line. An EDM device is added to the theodolite
and allows for the simultaneous measurements of the angle and the distance.
With the addition of a data collector, the total station interfaces directly with
onboard microprocessors, external PCs, and software. The ability to perform
all measurements and to record the data with a single device has
revolutionized surveying. Army topographic surveyors use the AISI, which is
addressed in detail in Section 111.
SECTION І - TARGETS
5-31. A target is generally considered to be a nonilluminating signal. There
are two general types of targets—tripods and poles. Both target types may
incorporate variations. Targets are constructed of wood or metal frameworks
with cloth covers. For easy bisection, a target should be as narrow as possible
without sacrificing distinctness. Triangular-shaped targets are the easiest to
bisect. Square- and rectangular-shaped targets are the second easiest to
bisect. Round targets are the hardest to bisect due to problems in pointing
during repeated observations. Round targets should be avoided whenever
possible. A target that subtends an angle of 4” to 6” of arc is easy to bisect.
Since 1" of arc equals 0.5 centimeter at a I-kilometer distance, 6” of arch
equals 3 centimeters at a 1-kilometer distance and 30 centimeters at a
10 kilometer distance. Under adverse lighting conditions, the target width
will have to be increased. To make a target readily visible against both light
and dark backgrounds, use material constructed of alternating bands of red
and white or orange and yellow. Flags may be added or the background may
be filled with blaze-orange cloth to contrast the target. All cloth used on the
targets should be slashed after construction to minimize wind resistance and
to avoid pilfering in areas where cloth may be valuable.
OPTICAL-THEODOLITE TARGET SET
5-32. The optical-theodolite target set is precise-survey equipment that is
generally used for short traverse lines (about 4 kilometers or less). This target
set (Figure 5-11) consists of a lower and an upper group. The lower group
consists of a tribrach with a three-screw leveling head, a circular bubble, and
an optical plumbing device. The upper group contains a plate with three
triangles; a long, level vial; and a lighting attachment. The upper group is
removable and is interchangeable with a theodolite
5-16 Conventional Survey-Data Collection
FM 3-34.331
Centering mark | Target frame
Target level
Tribrach assembly
Target base
; Tribrach lock lever
Circular level
4 —— —— —— Tribrach lock screw
Leveli
Optical-plummet A ы]
eyepiece
Figure 5-11. Optical-Theodolite Target Set
AISI TARGET SET
5-33. The AISI target set is a combination precise-survey target and infrared
signal reflector. It is used for angle and distance measurements. The target
assembly (Figure 5-12, page 5-18) consists of a lower and an upper group. The
lower group consists of a tribrach with a three-screw leveling head, a circular
bubble, and an optical-plumbing device that can be illuminated. The upper
group contains a long, level vial; a tiltable reflector/target for short-range
measurements; and a long-range reflector/target assembly. The long-range
assembly contains one to eight reflector prisms and three triangular-shaped
target attachments. The reflector/targets are nonilluminating. The short-
rangetiltable reflector/target may also be attached to a range pole that has an
attached circular bubble level.
Conventional Survey-Data Collection 5-17
FM 3-34.331
Figure Description
Prism
Special prism
Tiltable setout prism
Foot
Chuck
Knob
Twin prism holder
Sight target
Tribrach with illumination
Tribrach adaptor with level vial
Sight rod
Telescopic rod
Tripod
Complete eight prism holder
= Setting out and
tacheometry
Long-distance traversing
Figure 5-12. AISI Target Assembly
5-18 Conventional Survey-Data Collection
Tripod Target
FM 3-34.331
5-34. The tripod target is the most stable, simplistic in construction, durable,
and accurate. It ranges from a simple range poleto a tripod assembly that can
be permanently embedded in concrete. All targets are susceptible to the
effects of wind and precipitation. The tripod must be guyed or sand bagged
and plumbed, and its legs should be securely set-in to prevent lateral
movement. On uneven ground, one leg may have to be shortened or dug in to
maintain a symmetrical appearance from all directions.
Range-Pole Targets
5-35. A range-pole target is used when the station does not require precise
accuracy. The range pole is used to collect site-plan data quickly and in
volume.
TARGET SETUP
5-36. Observers sometimes have a difficult and tedious task locating targets.
Depending on the type of terrain and foliage in the area and in wooded areas
where the targets are not profiled or silhouetted, they are very difficult to
locate without direct sunlight shining on them. To expedite the locating of
targets, it is sometimes necessary to illuminate the target area. Generally
accepted procedures are as follows:
e Useofahandheld flashing mirror.
e Useofa strobe light or a portable light.
e Use of vehicle headlights.
5-37. Once a target area is located, it becomes a simple task to find the exact
location of the target. The use of iridescent cloth on the target in place of
regular signal cloth is recommended if the cloth can be interchanged.
5-38. In traverse operations where continual backsights and foresights are
needed and where distances are not excessive, target sets can be used in a
leapfrog technique. The actual distance a target can be seen depends on the
background, the lighting, and the weather. Care must be taken when pointing
a target at the observer so that the view is not distorted through the telescope.
A disadvantage of a target set is that only one at a time may be set at a
station. When setting a target, it must be plumbed exactly over a station. A
target is said to be plumb when it is centered to within 2 millimeters of the
point.
LIGHTED TARGET SETS
5-39. A target set is a precise-survey lighting device used for short traverse
lines (about 4 kilometers or less). When a target set is used for night
observations, it requires the attachment of an accessory lighting unit to the
back of the target. The lighting unit consists of a metal hood with a light bulb
mounted in the center. On the older target sets, the hood hangs on two small
metal studs mounted at the top rear of the target. On the newer target sets,
the hood slides down over the sides of the target from the rear.
Conventional Survey-Data Collection 5-19
FM 3-34.331
TARGET AND TRIBRACH ADJ USTMENT
PLATE BUBBLE
5-40. After the plate bubble has been centered, its position is checked by
rotating the target (or instrument) through 180°. If the bubble does not
remain centered, bring it halfway back using the foot screws to properly set it.
For example, if the bubble position is off the center by four division marks,
turn the foot screws to center the bubble until it is only off by two division
marks. The bubble should remain in this position while the target is rotated.
The target is now level and can be used, but the error should be removed by
adjusting the bubble tube.
5-41. The bubble can now be adjusted by turning the capstan screws at the
end of the bubble tube until the bubble is centered. Repeat the leveling
procedure until the bubble remains in the center of the tube. Adjustments
should be done in small increments, no more than half the error should be
adjusted out at one time. At the end of the procedure, make sure the capstan
screws are tightly secured.
CIRCULAR BUBBLE
5-42. Tribrachs use a circular level for rough and plate-fine leveling. After the
plate bubble has been adjusted, the circular bubble can be adjusted (centered)
by turning one or more of the adjustment screws located around the circular-
bubble assembly.
OPTICAL PLUMMET
5-43. The optical axis of the plummet is aligned with the vertical axis of the
target (or instrument) if the crosshairs of the optical plummet stay
superimposed on the center of the mark when thetribrach is revolved through
180°. If the crosshairs do not stay superimposed, the plummet can be adjusted
using the following steps:
Step 1. Level the tribrach and put the crosshair over the mark and mark a
point.
Step 2. Rotatethetribrach 120° and mark a second point.
Step 3. Rotatethetribrach a second 120? and mark a third point.
Step 4. J oin thethree points into a triangle.
Step 5. Draw a bisecting line from the center of the sides of the triangle to
form the center of the triangle (Figure 5-13[А]).
Step 6. Adjust the optical plummet to the center of the triangle by loosening
one side of the capstan screws and tightening the opposite screw
(Figure 5-13[B ]).
Step 7. Repeat the process to verify the adjustment.
Step 8. Ensure that all screws are snug after the adjustment is completed
and that as little stress as possible is exerted on the capstan screws during the
process.
5-20 Conventional Survey-Data Collection
FM 3-34.331
: | B
Bisect each side of Adjust optical plummet to
the triangle. the center of the triangle.
SIGNALS
POINTING
Figure 5-13. Optical-Plummet Adjustment
5-44. Signals are survey targets that are either illuminated by natural sunlight
or are electrically lighted by using batteries. The observations for all second-
order, Class! triangulation and traverse are usually done at night by using signal
lights because of more stable atmospheric conditions, which allow for better
pointings. Observations may be made during daylight hours if the work situation
prevents nighttime observations. The most commonly used signal light has a 5-
inch reflector. This signal light is used for lines of sight in excess of 8 kilometers.
Do not use the 5-inch light on lines of sight shorter than 8 kilometers. A rule of
thumb to follow for other light sizes is to add no more than 1-inch to the
diameter of the light size for each mile observed.
5-45. The exact horizontal and vertical pointing of the light is very important.
If thelight is not pointed exactly toward the instrument, only a portion of the
reflector will be observed. In some cases, this portion will not be plumbed over
the station mark. The instrument operator must check the pointing before
starting the observations by viewing the light through the telescope. During
hazy weather and especially on long lines of sight, the view through the
telescope may appear as a bright spot surrounded by a flare. The instrument
operator should request that the light keeper adjust the light slightly in a
horizontal and vertical arc whileit is being viewed through the telescope until
the best pointing can be determined. The best pointing is when the light is the
brightest. The light is then stopped and locked into position. If the lights are
Conventional Survey-Data Collection 5-21
FM 3-34.331
MASKING
FOCUSING
BRILLIANCE
STACKING
stacked, the bottom light must be pointed first. It can be adjusted for
brightness by adding or removing batteries. The light should never be
improperly pointed to reduce its brilliance (this will create an eccentric light).
The lighting attachment must be pointed directly at the observer to eliminate
the appearance of uneven lighting of the target's triangles.
5-46. A light can be masked to reduce the size and brilliance of the beam by
covering equal portions of the lens (both above and below and tothe right and
left of the center of the glass face). Opposite sides of the glass must be masked
equally to eliminate eccentricity. This type of masking is very good for
distances between 6 and 10 kilometers on normal nights. A sheet of orange
scribe paper is required, but any other color will work almost as well. When
using the orange paper as a masking material, the light will present an
orange glow with a brilliant white cross for the observer to pointing on. At
maximum ranges, the orange glow is practically invisible through the
telescope, and at minimum ranges, the glow will help in identification of the
light.
5-47. Thelight is focused by turning a screw at the rear of the bulb socket. By
turning this screw, the position of the bulb is changed in relationship to the
reflector. If the light is not properly focused, it will appear as a fuzzy ball in
the telescope. The light may be focused by shining it on a flat surface about
50 meters away and adjusting the size of the beam until it is slightly larger
than the light reflector. When no distant object is available, a field-expedient
procedure is to hold one's hand about 6 inches in front of the light and adjust
the light until a dark spot the size of a quarter appears in the center of the
beam.
5-48. The type of light bulb and the amount of voltage being used will
determine the brilliance of the light. The light is issued with two different
bulbs: a standard 3.7- and a 6-volt bulb. The amount of voltage needed will
vary depending on the lighting requirements. Various battery arrangements
are shown in Figure5-14. If dry-cell batteries are not available or are too
weak, a field-expedient procedure is to connect two lights (with 6-volt bulbs) in
a series and then connect them to a 12-volt wet-cell battery. Never apply more
voltage to a bulb than its rated value.
5-49. When lights are needed from the same station to several observers, the
signal lights are stacked, generally on a range-pole tripod (Figure 5-15). If
lights are stacked over a station, they must be leveled and plumbed over that
station mark. The lowest light must be leveled and plumbed first, then the
other lights should be attached and individually leveled. Care must be taken
not to knock the other lights out of plumb when attaching additional lights to
the pole.
5-22 Conventional Survey-Data Collection
FM 3-34.331
To lamps
1. Cells connected in series. Output 9 volts, 24 amperes.
7 5x083—083—082—(83—(82—9)
2. Cells connected in parallel. Output 11⁄2 volts, 144 amperes.
To lamps To lamps
Outputs are based on the
assumption of dry cells with
an average of 1*2 volts and
24 amperes each.
3. Cells connected in series/parallel. 4. Cells connected in series/parallel.
Output 3 volts, 72 amperes. Output 47 volts, 72 amperes.
Figure 5-14. Battery Wiring Diagram
Figure 5-15. Stacking of 5-Inch Signal Lights
Conventional Survey-Data Collection 5-23
FM 3-34.331
RANGING
5-50. When observations are made from a small (low) instrument stand, it is
sometimes impossible to plumb the lights directly over the station mark. If
this occurs, it is acceptable to use the lights on a range. The lights must be
aligned on a range to all stations with a theodolite. The standard theodolite
tripod or range-pole tripod is used as a stand and should be from 4 to
30 meters from the station. Care must be taken to avoid introduction of
eccentricities.
NOTE: A target set is used as a signal in the same way as when it is used as a target.
EXPEDIENT LIGHTING
5-51. In the absence of a lighted target, a reflector may be used. By pointing a
powerful, hand-held lantern flashlight at the reflector, a precise reflection will
be returned. There are many other types of expedient lights or signals that
can be used when standard equipment is not available or is inoperative. These
indude such things as the headlight of a vehicle, a masked lantern, a boxed
lightbulb, or chemical illumination lights. The survey-party chief must use
experience gained in the field and ingenuity to determine the proper
expedient for a particular condition or probl em.
SECTION Ill - AISI
5-52. The AISI is an electronic theodolite used to measure horizontal and
vertical angles and distances. It represents these measurements on a display
panel and can concurrently transfer them to a portable data-recording unit
(DRU). The DRU can then transfer the data to an external microprocessor for
printing, plotting, and further refinement by surveying software.
DESCRIPTION
5-53. The AISI has two modes—a construction-survey mode with a range of
2 kilometers and a topographic-survey mode with a range of 7 kilometers. The
AISI mounts on standard military tripods and consists of the following
modular subassemblies:
* An electronic theodolite (a digital, automatic angle- and distance-
reading/recording instrument with an electronic display/control
panel).
* A DRU (an external memory device for storing data from the
theodolite).
5-54. The AISI interfaces with microprocessors, printers, and plotters. It
transfers digital data directly from its DRU (via а cable interface) to the
microprocessor. The data is then refined by a fully integrated, 3D, ground-
modeling, drafting-design system. The data can also be manually input to any
CAD software program.
5-55. The AISI measures distances from 2 meters to 7 kilometers with a
digital readout of 1 millimeter and is accurate to +2 millimeters +3 ppm over
the measured distance. The horizontal and vertical angles are measured to an
5-24 Conventional Survey-Data Collection
FM 3-34.331
accuracy of 1" of arc. The AISI has an elecronic leveling device called a dual-
axis compensator and adjusts for horizontal and vertical leveling with errors
of 6" or less. The system has built-in communications with a range of 1 mile,
an illuminated reticle for night operations, a 60-kilobyte memory capacity,
and an alphanumeric keyboard and is powered by two dual-voltage,
rechargeable, 12-volt nicad battery packs.
COMPONENTS
LEVELING
5-56. A detailed list of components for the AISI is described in TM 5-6675-
332-10. The basic components for the AISI are shown in Figure 5-16, page
5-26. They are as follows:
* Atransport case.
* A tribrach with an optical plummet, a battery pack, and a tribrach
battery cable.
* Alens and an eyepiece cover.
* ADRU and a DRU/AISI/battery cable.
e |nternal and external nicad batteries.
• А battery charger and a charging converter.
5-57. The AISI uses a leveling device called a dual-axis compensator. It is an
electronic device that senses the pull of gravity and uses two imaginary planes
(one parallel to the instrument's face and the other perpendicular to that
plane) at the base of the instrument for determining the level. The display
simulates an actual bubble level, and foot screws are used to adjust the
display bubble. The instrument then adjusts the horizontal and vertical axis
to compensate for the instrument not being level. The working range of the
compensator is 6’. That means that the instrument can be up to 6' off of level
and still adjust the horizontal and vertical axis. The sensitivity of the display-
bubble graduations is 6" in the fine-level mode and 20" in the coarse-level
mode.
QUICK CHECK
5-58. A quick check is used to see if the AISI needs to be run through a
collimation test. This procedure should be done at least once a day and also
every time the instrument operator changes. Any time the quick check fails,
the AISI should be calibrated. This check compares the sightings at a point
target in the reverse and the direct modes. Pressing the angle-measure (А/М)
key for each sighting will show the difference in the horizontal aim (dH) and
the difference in the vertical aim (dV) on the screen. Failure is determined
when the check of the dH and the dV is morethan 5" for horizontal and more
than 10" for vertical from the mean. The collimation test will produce a value
to correct the angles (Figure 5-17, page 5-27). The procedures for the
collimation test are described in TM 5-6675-332-10.
Conventional Survey-Data Collection 5-25
FM 3-34.331
Transport Case
Tribrach battery
© cable
Eyepiece
cover
Battery
Box
TC— On-off
switch
Tribrach Illumination
intensity control
Plug for
Foot screw
battery box Locking
Foot screw
"m adi
Optical >
plummet Foot screw
DRU/AlSI/battery cable
Internal Nicad Battery External Nicad Battery
Hook for tripod
te
Fuse
Cable connection
Charging time: 14 hours. Charging time: 14 hours.
Use time: 2-3 hours. Use time: 3-4 hours.
Charging Converter
Connections for
Super Charger
internal battery
Plug to Plug to wall
charger m ч
Connection for
external battery
Plugs to converter
Figure 5-16. AISI System Components
5-26 Conventional Survey-Data Collection
FM 3-34.331
Correction
Direct reading
Reverse reading
Figure 5-17. Quick-Check Example
DATA COLLECTION
5-59. The AISI has two ways of collecting data—the coordinate method and
the traverse method. In the coordinate method, all coordinates of points are
collected in the field and all computations are conducted internally in the
AISI. In the traverse method, all data is stored in the AISI in the form of raw
angles and distances. This data is then downloaded into a survey software to
compute coordinates. Surveyors determine which method to use. Table 5-2
shows the pros and cons for each method.
Table 5-2. Two Methods of AISI Data Collection
Coordinate Method Traverse Method
Pros Cons Pros Cons
Can use without survey User needs їо һауе | Known coordinates do not alba 1O KNOWNOW
А i А to operate the survey
software. starting control. have to be known in the field.
software.
Can label/stake points in Coordinates can Topographic points can be
the field. not be readjusted. readjusted.
No proof of where Raw data is stored for proof of
or how coordinates | how the coordinates were
were derived. derived.
COORDINATE METHOD
5-60. The coordinate method is used to collect coordinates for points that
require little or no use of a survey software. Before using this method, the
user-defined sequence (U DS) and coordinates for the starting control must be
entered into the AISI. The result of this method is a visual display of
Conventional Survey-Data Collection 5-27
FM 3-34.331
northings, eastings, and elevations. The angles are collected in Facel only.
These points are also stored in a job file and can be converted to a points file
with the use of survey software.
TRAVERSE METHOD
DATA STORAGE
JobFiles
Area Files
5-61. The traverse method is used to collect data that will be processed and
adjusted by survey software. This method provides a digital copy of the
collection process. The angles are measured in Facel and Facell and errors
can be accounted for. The results can be compared to standards and
specifications. Before starting the UDS, the starting coordinates must be
entered intothe AISI.
5-62. The AISI is equipped with internal memory and an external memory
device or DRU for storage of raw data, point information, and calculated
coordinate data. Memory units make it easier to check and identify the data
after collection. Two types of data (survey measurements [job files] and known
coordinates and elevations [area files]) are saved in the memory. These job
and area files consist of separate expansive memories and can be updated
individually at any time.
5-63. J ob files are given a numeric, alpha, or alphanumeric title to permit
later identification. All survey data is stored in a job file and includes the
calculated coordinate and elevation data. When complete, these files can be
transferred to a PC.
5-64. Area files can be manually input and then stored or transferred from a
PC. Several different files can be prepared in advance of the particular survey
job. All known data can be stored for a project before departing to the job site.
FILE TRANSFER
5-65. TheAISI can be connected to a PC or an external DRU. Information can
be transferred between either peripheral via a built-in serial interface. The
instrument is connected to the DRU by a DRU/AISI/battery cable. The
connection from the instrument tothe PC is made with a standard 9-pin cable.
Data transfer through the serial port requires that the standard parameters
or protocol be set. When job and area files aretransferred, they are copied but
not erased. The original file remains in the device and serves as a backup for
the project. Files can be deleted manually from the instrument or from the PC.
Deleting files should only be done after the project is completed and properly
archived.
FILE EDITING
5-66. The edit module allows viewing and editing of data within the recording
device and the external DRU or directly from the keyboard of the instrument.
5-28 Conventional Survey-Data Collection
FM 3-34.331
Edit functions include search, delete, insert, and change. The editing features
are menu driven with the command options displayed on a screen. Options are
selected using the keyboard. Іп the editing module, errors such as HT and
station number can be checked and changed by the instrument operator іп the
field to ensure correctness before leaving the site.
COMMUNICATIONS
5-67. The AISI contains an internal communication system that enables
speech communication to be carried out from the instrument to the receiver
prism. This system is a one-way communication from the instrument to the
reflector prism. There is a small microphone on the instrument panel that is
activated from the control panel. When activated, the measuring beam is used
entirely for speech transmission. This provides a communication channel
without interference and without the need for a special radio-frequency
permit. T
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