STUDY OF THE NOISE PRODUCED BY TRAINS COMING TO A HALT

摘要

The noise resulting from stopping a moving train is often a source of annoyance to both passengers and people who work and sometimes live in the vicinity of railroad stations. The present study attempted to define the characteristics of noise produced by the brakes of trains used in Portugal. The braking process varies widely from train to train and within the same type of train. Therefore, the results of the measurements had to be statistically analyzed. The parameters used to describe noise in this situation were the L_(Aeq) the L_(10) and the L_(90) and the corresponding measurements took place both during the daytime and the nighttime period. Data was also obtained as a function of time and in 1/1 octave bands. The results show that there is a direct correlation between the maximum speed of a given train and the corresponding sound pressure level when the train is stopped. It was found that passenger trains that belong to the new, upper class of railroad transportation were the noisiest ones at the time of braking. As to the railroad itself, it was found that long welded rails make a favorable contribution to the decrease of noise levels. It was also found that the nighttime period was less noisy than the daytime period, in particular in terms of L_(Aeq) and L_(10).