The relationship between urban combined traffic noise and annoyance: an investigation in Dalian, north of China.

Several residential areas in Dalian, north of China, were selected to investigate the influence of combined traffic noise pollution on urban residents. The software Cadna/A was used to estimate the day-night equivalent noise level (L(dn)) at 1m from the windows of each building, which were modified according to the actual data. Annoyance has been identified as the most important psychological impact of noise. A face-to-face survey on annoyance was carried out among 1536 local residents between the ages of 15 and 75 years. In this study, the relationship between the percentage of "highly annoyed" persons (%HA) and L(dn) was determined. The L(dn) was measured and identified as railway dominant noise, road traffic dominant noise or road-rail combined traffic noise. We find that when L(dn)>63.5 dB, the %HA due to the road-rail combined traffic noise was significantly higher than that due to the one dominant noise source with the same L(dn). Thus, it is suggested that the planning permission buildings whose L(dn) of road-rail combined traffic noise exceeds 63.5-dB be reviewed more strictly. The relationships between %HA induced by different traffic noise and the distance to transportation artery (s) were analyzed. The results showed that as the distance to transportation artery increased, the %HA due to different traffic noise gradually decreased. Furthermore, the %HA due to the road traffic dominant noise at close range (1 m≤s≤50 m) was lower than that at a more remote location (51 m≤s≤100 m), which might be ascribed to the greater tolerance of the noise by the residents.