Dispersion in an Urban Cross-Street Intersection

Abstract

A typical urban street intersection comprises of roadways, pedestrian walkways, and tall buildings on the sides. Due to the large number of vehicles plying on the urban streets, the pedestrians are exposed to vehicular pollution. With the increase in the density of automobiles, there is a bigger threat to pedestrians. The current study investigates pollution dispersion in the case of an eight-story building across a cross-street intersection. The study includes the effect of the aspect ratio (AR = 0.5, AR = 1, and AR = 2), a ratio of building height to road width, on flow patterns and dispersion. The second part of the work includes the effect of wind approach angle (0º, 30º, 45º, 60º) on the dispersion. It is found that the pollutant mass concentration at the nose level of pedestrians is strongly influenced by the aspect ratio wherein the taller building provides less exposure to pedestrians due to the lateral dispersion. The wind approach angle also affects the pollutant concentration at the nose level. The exposure to pollutant is skewed along the length of the road walkways in the case of 30º and 60º. However, the dispersion in more uniform in the case when wind approach angle is 45º. © The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd. 2025.