Noise exposure of the residential areas close to urban expressways in a high-rise mountainous city

Abstract

Urban expressways can generate excessive noise in the surrounding urban areas, and it tends to be more complex in mountainous cities, due to the undulating terrain, dense population and compact urban structures. This article aims to investigate the objective acoustic environment and road traffic noise exposure, including the noisy evaluation, annoyance and effect of roadside apartments in residential areas close to urban expressways in the high-density, high-rise, mountainous city of Chongqing. Three housing estates were selected for a series of field measurements, questionnaire surveys and noise mapping. There was a significant negative correlation between night-time noise levels and the distances to the urban expressway (p < 0.01). Moreover, the differences between the daytime and night-time noise levels were generally insignificant (0.7 to 3.6 dBA) at the roadside locations. Differences in reaction to noise exposure in a variety of both person-related and housing condition variables were found, especially between roadside and non-roadside locations or residents. In addition, 75.0% of roadside residents identified the traffic noise as ‘very’ or ‘extremely’ annoying, and 66.7% of them regarded the acoustic environment as the priority environmental factor that needs to be improved. Difference in the ‘bedroom-window orientation’ had a significant effect on subjective noise evaluation. Rectangular-shaped apartments along the roadside obtain better noise reduction capacities than tower-blocks through the simulation. The acoustic performance of road cuttings, as an appropriately designed earth embankment, is improved along with deeper vertical alignment, and slope angles of 30° and 75° should be avoided.