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| Re: To el or not to el, that is the question! (75644) | |||
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Re: To el or not to el, that is the question! |
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Posted by Stephen Bauman on Tue Apr 19 09:25:46 2005, in response to To el or not to el, that is the question!, posted by rashidas on Mon Apr 18 23:29:33 2005. the last new elevated subway was the Astoria line opened during WWI.The last new elevated structure in Queens was the stretch between the Archer Avenue subway and the Jamaica Ave El near 121st St. It was built in the 1980's. It is extremely noisy, noisier than the old WWI Jamaica Ave El, as anybody who has stood under it can testify. AirTrain claims to be very quiet. One reason is the elimination of propulsion noise due to the use of linear induction motors. That has no technology transfer to NYCT operations. A second reason is the use of baffles on the sides of the structure. This deflects the noise upward rather than permitting the sound to travel horizontally or downward. That works for observers at ground level but what about people living adjacent to the structure at the 4th or 5th floor levels? A third reason are the rubber pads between the top of the pillars and the beam structure supporting the tracks. This reduces the transmission of vibration to the ground. This reduction is due to the spring-like properties of the rubber. Rubber loses this property, when it is repeatedly subjected to cold temperatures. My own observations, made with my trained ears, indicates that AirTrain's noise level is a couple of db's higher after one year of operation. |
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