Effect of reversible lanes on the concentration field of road-traffic-generated fine particulate matter (PM2.5)

Abstract

Fine particulate matter (PM2.5) poses a potential threat to human health. The effects on PM2.5 before and after implementing a reversible lane were analysed based on a road segment. A simulation experiment was conducted, and the results were verified with normalized and measured concentration data. The PM2.5 concentration fields were studied in a series of cases with three different aspect ratios and two wind speeds. The average PM2.5 concentrations at y = 0.5, y = 1.5, and y = 2.0 m after the implementation of the reversible lane decreased by 2.35 %, 2.45 %, and 2.70 %, respectively. The effect of implementing a reversible lane on reducing PM2.5 concentration was outstanding when the aspect ratio H/W was 2:1, followed by H/W = 1:1 and H/W = 1:2. When the aspect ratio H/W was 2:1 and wind speeds were 1.2 and 3.6 m/s, the average PM2.5 concentrations at y = 1.5 m after the implementation of the reversible lane decreased by 84.14 % and 45.45 %, respectively. These findings will assist in designing streets with appropriate aspect ratios, developing an orderly strategy to implement variable lanes throughout an entire road network, and controlling road traffic flows to reduce the potential public harm of PM2.5.