Influences of Crest Vertical Curve Curvature on Exhaust Emissions of Heavy-Duty Diesel Trucks at Grade Change Point Section in Highway.

The vertical curve is a major factor affecting vehicle exhaust (CO₂, CO, NO_x, PM2.5) emissions. This article takes a heavy-duty diesel truck as a typical vehicle, combining instantaneous speed, acceleration and the vehicle-specific power VSP to divide the operating mode, and the exhaust emission of a heavy-duty diesel truck is then calculated by using MOVES. Finally, the environmental modification factors (EMFs) are used to evaluate the influence of curvature change on the exhaust emissions. The results show that CO₂ and PM2.5 emissions of heavy-duty diesel trucks are increasing with the curvature of the crest vertical curve changing; with the increase and decrease of curvature K of the crest vertical curve by 50%, CO and NO_x emissions showed an increasing trend. Among the four main emissions, CO₂ emission amount is the largest, followed by NO_x, CO and PM2.5. The emission rates of CO₂ and PM2.5 increase with the increase of curvature of the crest vertical curve, and the minimum values of CO₂ and PM2.5 emission rates are 46.7 g/s and 0.022 g/s, respectively. The emission rates of CO and NO_x increase with the increase of curvature. The minimum point of emission rates of CO and NO_x are 0.042 g/s and 0.259 g/s, respectively. [ABSTRACT FROM AUTHOR]