Understanding Roadside Air Quality in a Traffic-Dominated Urban Corridor: A Case Study of Sangkuriang Road, Cimahi Utara, Indonesia

Abstract

Traffic emissions and local dispersion conditions exert a considerable influence on urban roadside air quality. This study aims to assess the ambient air quality and pollutant dispersion, resulting from the daily traffic on Sangkuriang Road in Cimahi Utara-Indonesia by
integrating traffic characteristics, roadside field measurements, and CALINE4 dispersion modelling to evaluate near-road pollutant behaviour. Traffic characteristics were analyzed using volume, composition, speed and volume-to-capacity ratio (VCR) while ambient concentrations were measured and compared with national air quality standards. Traffic and meteorological conditions were used to simulate the dispersion patterns using the CALINE4 line-source model. The motorcycles dominated the flow of traffic, with VCR values indicating stable conditions. Concentrations of pollutants at monitoring site were lower than the national limits, but dispersion modelling indicated higher concentrations close to the road that decreased rapidly with distance from traffic. The combined influence of motorcycle dominated traffic and low wind speed conditions (0.28 m/s) likely reduced pollutant dispersion and enhanced near-road pollutant accumulation. CALINE4 was able to reasonably capture the observed roadside pollution patterns and near-road dispersion behaviour. The results underscore the need for a combined monitoring and modelling approach in order to better understand spatial heterogeneity and exposure risks of near-road environments.