NOISE GENERATED BY SUBWAYS ABOVE GROUND AND IN STATIONS

Abstract : The report presents and discusses subway noise data acquired near various outdoor subways in seven European cities as well as noise generated by trains entering and leaving nine subway stations. Outdoor noise is measured at distances between 3 and 300 feet. It was found that there are substantial variations (of the order of 20-30 dB) in levels generated by trains at a given distance on elevated sections, depending on whether the supporting structure is steel, concrete, or earthen. Rail joints and poor quality wheels are shown to increase noise levels by 8-10 dB. Trains on rails which have been ground smooth generate 6dB(A) less noise than trains on unground rails. Effects of train speed, distance from a train, and track grade are analyzed. Finally, noise levels in small stations lacking significant sound-absorbing surfaces are found to be 22 dB(A) higher than larger acoustically well-treated stations. (Author)