Evaluating the Emission and Energy Impacts of Automated Buses on Urban Expressways

Abstract

In recent years, a series of traffic problems have emerged with continuously increasing traffic. Connected and autonomous vehicles (CAV) technology is considered to be an effective way to relieve these problems. It is believed that buses, trucks, and other special vehicles could be among of the first application areas to promote the development of CAV technology. Because of their features of high emissions of pollutants and high energy consumption, the improvement of environmental benefits for such heavy vehicles as buses is the focus in this research. Therefore, this paper aims to evaluate the impact of automated buses on emissions and energy consumption on urban expressways. To achieve the research objectives in this paper, the established automated buses model is embedded into the simulation platform with VISSIM dynamic link library. Models are developed for emissions and energy consumption calculations based on vehicle-specific power to quantify the environmental impact of automated buses. Two improvement strategies: dedicated managed lane and dedicated bus lane, are designed. Finally, a VISSIM simulation platform based on the Fourth Ring Road in Beijing (Xueyuan Bridge to Haidian Bridge) is built to conduct case studies. The results show that CAV technology in buses can reduce exhaust emissions and save energy. Moreover, the managed lane strategy brings a significant reduction in the emissions and energy consumption of automated buses. These findings can be used for the development of automated bus operational strategies focused on environmental benefits.