Transportation System Plan 2018-2038

secondary measure (v/c ratio) provides an indication of capacity sufficiency at an intersection. When the v/c ratio exceeds 1.0, the am ount of auto dem and at the facility exceeds the capacity of the facility to serve that dem and. Poor levels of service are often experienced when the v/c ratio exceeds 1.0. The City Council established a LOS policy for the City of Medford as part of the Transportation System Plan based partly on the results of this study , but also on other factors such as street connectivity , econom ic developm ent im pacts, neighborhood livability , potential air quality impacts, etc. The analy sis in this Appendix focuses on three potential LOS standa rds: Peak Hour LOS D, Peak Hour LOS E, and Multi-hour LOS D. The first two standards require th at a LOS D or E, respectively , be m et during the hour of m aximum traffic volum e during a ty pical weekday (generally during the PM peak hour, which generally occurs between 4:00 and 6:00 PM). The sec ond standard would allow in tersections to operate at LOS E or LOS F during the peak hour, as long as the LOS does not exceed D during the second- highest volum e hour. The following sections include an assessm ent of each potential LOS standard as described above, as well as a secondary standard of v/c ratio less than 1.0. Projects required to m eet each of the standards were provided based on 2023 forecast traffic volum es. Cost estim ates were also prepared as part of the LOS Study for the identified projects under each LOS sta ndard. These cost estim ates are reflected in the recom mended street im provem ent project lists described in Chapter 13. Analy sis Methodology Traffic Operations Analysis Methodology Development of Traffic Operations Model Traffic operations at intersections throughout the C ity of Medford were analy zed using SYNCHRO, a traffic analy sis software tool. SYNCHRO auto mates the analy sis procedures outlined in the Highway Capacity M anual (HCM) for signalized and stop-controlled intersections. The HCM provides a nationally accepted, standardized analy sis procedure the determ ining average vehicle delay , level of service (LOS), and volum e-to-capacity (v/c) ratios at signalized and stop-c0ntrolled intersections. SYNCHRO explicitly calculates the platoon factor used in the HCM m ethod to account for the effect of signal progression. The program provides output data in the form of average intersection delay (in seconds per vehicle) and corresponding LOS, intersection v/c ratios, 95th-percentile queue lengths and signal phase lengths (for signalized intersections). SYNCHRO also optim izes phase splits, cy cle lengths, and intersection offsets to m inimize intersection and network delay . Version 5.0 of SYNCHRO was used to evaluate signa lized and unsignalized intersection perform ance. In order to obtain intersection v/c ratios, an “HCM Signalized” report was obtained from SYNCHRO. The “HCM Signalized” report provides slightly different average vehicle delay values than the standard SYNCHRO output. The m ain differences result from the fact that SYNCHRO uses a percentile delay method, which assum es that the traffic dem and will fluc tuate over the course of the analy sis period. The HCM m ethod assum es that the dem and will be constant over the analy sis period. SYNCHRO will often assign a very low amount of signal tim e to low volum e movem ents based on the prem ise that the particular signal phase servicing that m ovem ent w ould not be “called up” during every phase. Using these calculated phase lengths in the HCM analy sis often results in long average delay s because the SYNCHRO determ ined signal phase length is not sufficient for servicing vehicles during every signal cycle. As described later in this report, this problem was rectified by setting low-volum e movem ents with “m inimum recall” which ensures that the minimum signal phase tim e is provided for the given movem ent during every signal cy cle. G-2