Analysis of the impact of speed and lane distribution on pollutant concentrations in the urban street environment

Abstract

This article presents the results of an in-depth analysis of the relationship between lane-specific traffic characteristics—namely, lane position and average vehicle speed—and the concentration levels of major air pollutants (CO, NO, NO₂, SO₂) in an urban environment. Field measurements were conducted in spring 2025 on straight, well-maintained segments of urban streets in Tashkent with different lane configurations (4, 6, and 8 lanes), under favorable meteorological conditions. The study examined how the position of traffic lanes (from right-most to left-most) and their corresponding average speeds affect pollutant levels. The data revealed a consistent trend: pollutant concentrations are highest on the first (right-most) lane, where average speeds are lowest, and gradually decrease toward the center and left-most lanes, where speeds are higher and traffic flow is more stable. This pattern was particularly evident for NO and NO₂, with frequent exceedances of the maximum permissible concentrations, while CO and SO₂ remained within acceptable limits in most cases. The findings underscore the role of stop-and-go traffic, common in right-hand lanes (due to loading, unloading, and public transport), in intensifying localized air pollution. These results highlight the importance of integrating lane-specific traffic flow characteristics into urban planning and traffic management policies. Recommendations include reducing heavy vehicle traffic in right-hand lanes during daytime hours and enhancing traffic flow efficiency to mitigate pollutant buildup in high-exposure zones. This study provides a practical foundation for improving air quality through street design and targeted transport regulations.