Exposure to noise on board locomotives

Personal and area noise dosimetry measurements were taken in the cabs of leading and trailing locomotives on 48 trips, under winter and summer conditions, on 9 different routes. The mean equivalent sound level (L(EQ), 3 dB exchange rate, 50 dBA threshold) of the engineers and conductors was 84 dBA during winter and 88 dBA during summer. The corresponding time-weighted average levels (L(TWA), 5 dB exchange rate, 80 dBA threshold) were 80 and 84 dBA respectively. The L(EQ) of 56% of the engineers sampled was > or =85 dBA and of 13% was > or =90 dBA. Plots of L(EQ) time history show that under normal operating conditions L(EQ) reaches its steady-state value in about 3 hours. The mean noise levels in the trailing cabs were lower than the personal exposure levels of the engineers and conductors. The mean L(EQ) on the engineer and conductor sides was 80 dBA during winter, and 85 dBA during summer. Locomotive configuration has a significant effect on the noise levels in the trailing cab. The forward-backward configuration resulted in higher noise levels than the forward-forward configuration. Octave and one-third octave band spectra taken during a variety of locomotive operating conditions are presented. The octave band centered at 31.5 Hz contains nearly 46% of the acoustical energy, and those centered at and below 250 Hz contain nearly 99% of the acoustical energy. Wheel-rail interaction appears to be the predominant source of the low frequency noise. Recommendations for controlling exposure are made.