Noise exposure of residential areas along LRT lines in a mountainous city

Abstract

Light rapid transit (LRT) has been widely used in a number of Chinese cities in recent years. Different from plain cities, the urban areas in mountainous cities are featured with dense road networks and high density of buildings. The noise impact of urban LRT could be more complex and significant due to the special morphological conditions in mountainous cities. This paper aims to investigate the noise exposure of residential areas along LRT lines in a typical mountainous city, namely Chongqing in Southwest China, through a series of field measurements and questionnaire surveys. Eight typical spatial configurations were classified to represent the relationships between LRT lines and urban mountainous environment. Both the outdoor and indoor acoustic environment of residential areas along LRT lines largely exceeded the national standards by up to 15dBA, with dominant at low frequencies. The LRT noises tend to be more dominant on the 'below track' and 'passing through' rather than 'above track' areas or 'facing towards' locations. Good agreements were achieved between acoustic measurements and subjective evaluations from the local residents. Residents in the noisier areas tend to be more annoyed and influenced by the LRT noise, and 63.2% of interviewed residents once were awakened by the LRT noise. Among various urban noise sources, LRT noise resulted in the largest percentages of highly annoyed residents (30.9%), and acoustic environment was identified by 42.2% of the participants as the most urgent environmental factor to be improved. The preferred control strategies for LRT noise are possible but limited in practice. Moreover, noise sensitivity and age might significantly affect LRT noise annoyance and impact, whereas window glazing and residence time have no significant influence.

Keywords: Annoyance; LRT; Mountainous city; Noise exposure; Residential area.