Replacing diesel buses with electric buses reduced residential low frequency noise

Low frequency noise (20- 200 Hz) from combustion engines typically dominates the indoor sound environments and is a source for annoyance and sleep disturbance. This study investigated the impact on low frequency noise when diesel operated buses were replaced by electric buses along a bus line in Gothenburg, Sweden. Noise measurements were performed indoors and outdoors for a selection of apartments directly exposed to bus traffic as well as for reference apartments, before and after the intervention. In addition, noise levels were calculated. The results show a significant reduction of the indoor low frequency noise in the range 40- 80 Hz in the apartments directly exposed to passing buses, both during bus passages (on average 10 dB), and in one-hour measurements (on average 5 dB). The results further show that A-weighted values fail to accurately represent the reduction in noise achieved by the intervention.