New York City Subway
Noise

Rolling stock on the New York City Subway produces high levels of noise that exceed guidelines set by the World Health Organization and the U.S. Environmental Protection Agency. In 2006, Columbia University's Mailman School of Public Health found noise levels averaged 95 decibel (dB) inside subway cars and 94 dB on platforms. Daily exposure to noise at such levels for as little as 30 minutes can lead to hearing loss. Noise on one in 10 platforms exceeded 100 dB. Under WHO and EPA guidelines, noise exposure at that level is limited to 1.5 minutes. A subsequent study by Columbia and the University of Washington found higher average noise levels in the subway (80.4 dB) than on commuter trains including Port Authority Trans-Hudson (PATH) (79.4 dB), Metro-North (75.1 dB) and Long Island Rail Road (LIRR) (74.9 dB). Since the decibel scale is a logarithmic scale, sound at 95 dB is 10 times more intense than at 85 dB, 100 times more intense than at 75 dB, and so forth. In the second study, peak subway noise registered at 102.1 dB.

For the construction of the Second Avenue Subway, the MTA, with the engineering firm Arup, worked to reduce the noise levels in stations. In order to reduce noise for all future stations starting with the Second Avenue Subway, the MTA is investing in low-vibration track using ties encased in concrete-covered rubber and neoprene pads. Continuously welded rail, which is also being installed, reduces the noise being made by the wheels of trains. The biggest change that is going to be made is in the design of stations. Current stations were built with tile and stone, which bounce sound everywhere, while newer stations will have the ceilings lined with absorbent fiberglass or mineral wool that will direct sound toward the train and not the platform. With less noise from the trains, platform announcements could be heard more clearly. They will be clearer with speakers spaced periodically on the platform, angled so that announcements can be heard by the riders. The Second Avenue Subway has the first stations to test this technology.
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