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Table 24.7: Typical Levels of Ground -borne Vibration <br />Typical Vibration Source <br />Blasting from Construction <br />Projects <br />Bulldozers and other heavy <br />tracked construction equipment <br />Commuter rail, upper range <br />Rapid transit, upper range <br />Commuter rail, typical <br />Bus or truck over bump <br />Velocity Lever) <br />(50-ft from Source) <br />100 <br />95 <br />85 <br />80 <br />75 <br />Human/Structural Response <br />Threshold, minor cosmetic <br />damage to fragile buildings <br />Difficulty with items such as <br />reading a video screen <br />CC <br />Residential annoyance, <br />infrequent events <br />CC <br />72 Residential annoyance, <br />frequent events <br />Rapid transit, typical 70 <br />Bus or truck, typical <br />Typical background vibration <br />CC <br />63 Limit for vibration sensitive <br />equipment. Approximate <br />threshold for human <br />perception of vibration. <br />52 Imperceptible <br />(1) RMS vibration velocity level in VdB relative to 10-6 inches/second. <br />Vibration Impact Criteria <br />The criteria for environmental impact from ground -borne vibration and noise are based <br />on maximum levels for a single event. The criteria presented in Table 24.8 account for <br />variation in project types as well as the frequency of events, which differ widely among <br />projects. The criteria are primarily based on experience with passenger train operations <br />with only limited experience from freight train operations. The difference is that <br />passenger train operations, whether rapid transit, commuter rail, or intra-city, create <br />vibration events that last less than 10 seconds. A typical line haul freight train is about <br />5,000 feet long and would take two minutes to pass at a speed of about 30 mph. <br />23/24-8 <br />