Abstract

Traffic authorities have taken various measures to mitigate vehicular-source pollution emissions, among which setting speed limits has been proved to be effective. However, most of the existing macroscopic research propose idealized mathematical models to design optimal speed limit from the perspective of network equilibrium, and the simplified pollution emission functions cannot accurately reflect the emission mechanism. In order to improve the accuracy of emission calculation and obtain more reliable speed limit schemes in a large-scale network, an integrated traffic simulation approach was proposed herein to derive environment-friendly road speed limit schemes. First, this paper built an integrated simulation framework to portray traffic operations and emissions comprehensively. Subsequently, a toy network was employed to demonstrate how to obtain environment-friendly speed limit schemes using this framework. Then this paper utilized it to determine the corresponding optimal speed limit schemes on the Second Ring road network in Beijing under different scenarios. The results indicated that traffic authorities should impose adaptive rather than fixed speed limits according to traffic period and emission reduction priority. Moreover, imposing the derived speed limit schemes, the amounts of total emissions, hydrocarbons, carbon monoxide, nitrogen oxides, carbon dioxide, and fine particulate matter decreased by 2.24%, 0.72%, 0.13%, 1.61%, 2.32%, and 5.35% during peak hour, and by 8.31%, 0.60%, 1.92%, 7.16%, 8.60%, and 8.72% during off-peak hour respectively.