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Sound engineers study I-5 noise to prepare for construction By MELISSA MARTIN How far will sound carry when beeping backhoes, cement trucks and paving rollers start working on the Interstate 5 viaduct that runs through the middle of town? That's the question acoustical engineers are asking this week as they analyze freeway noise in preparation for a $15 million viaduct project set to begin January 2003. Sound engineers will determine whether construction equipment will echo into Tripp Street homes, just below the freeway viaduct, or drift to the Rogue Valley Mall several blocks away. "Because of the way the freeway is raised and the way sound travels, it might be that people closest to the viaduct could be less impacted," said Cory Crebbin, Medford's director of public works. "With the right atmospheric conditions, you can hear things that happen downtown over on the east side." The state is measuring viaduct traffic to give the city an existing noise level before construction begins. The city is granting the state an exemption to its noise curfew rules so the Oregon Department of Transportation can run 24-hour crews to quickly complete the work on the busy stretch of highway. From Hawthorne Park, downtown Medford freeway traffic measures between 59 and 69 decibels, about as loud as a conversation between two people standing three feet from each other, said Dave Goodwin, senior acoustical specialist for the Oregon Department of Transportation. By comparison, the loudest Britt Music Festivals concert last summer was the rock group Huey Lewis and the News, which broke the city of Jacksonville's 92-decibel rule. A lawn mower is almost as loud, 90 decibels, but a chainsaw is louder, 100 decibels. Engineers gathered data last week and will analyze it and determine how to mitigate the noise before the construction project begins. Crews will work 24 hours a day, seven days a week so the job can be done by June or July. "We're turning a 11/2-year-project into a six- or seven-month project," said Frank Stevens, project leader for ODOT. "We don't want to have such a vital bridge worked on for so long." Crews will replace the bridge deck worn after 40 years of studded tires, loaded trucks and 45,000 vehicles passing over it daily. They will repave it with a durable, sand-blasted concrete. They will also reinforce the bridge's 48 beams with concrete to withstand an earthquake and rebuild the bridge rails. The 3,222-foot bridge over the middle of Medford is the longest in Oregon, not counting the four-mile Astoria span over the Columbia River, Stevens said. "It's structurally sound," Stevens said. "This project will give this bridge an added life expectancy of 20 years." But once construction crews start working from the viaduct, which measures between 16 and 30 feet from the ground, the sound challenges will begin. The trees in Hawthorne Park and Medford's taller buildings may help serve to shield the sound away from the ears of the people who live and work downtown, Goodwin said. But height, along with air temperature, helps determine how far sound travels, said Garon Wells, owner of Garon Lee Sound of Jacksonville. "In our business, height is everything," Wells said. Sound crews during a concert, for example, elevate speakers so people sitting in the back of the auditorium can hear the musicians on stage, he said. "Sound is almost like a solid object," Wells explained. "It's like throwing a baseball. If you throw it over somebody's head, you will miss them. But if you're 6 feet tall and you throw it to somebody who is 6 feet tall, you're going to hit them. "That's like a sound wave," Wells said. "If you're in line with it, it's going to hit you." Reach reporter Melissa Martin at 776-4497, or e-mail [email protected] Mail Tribune Home | Ottaway Newspapers, Inc. | Dow Jones & Co., Inc. | Privacy | Contact Us Copyright � 2001 Mail Tribune, Inc.