Analysis of road capacity and pollutant emissions: Impacts of Connected and automated vehicle platoons on traffic flow

Connected and Automated Vehicles (CAV) are currently not intelligent enough to deal with complex traffic conditions. CAVs traveling in platoons can reduce external interference and further improve road capacity. Therefore, a mixed traffic capacity gain formula was constructed, considering both communication interaction and size limitations of CAV platoons. CAVs are divided into three types in a mixed traffic environment in terms of different states and positions. A model was constructed to examine how several parameters affect capacity, and these capacity-improving parameters were used to indicate coefficients of headway gains. Additionally, an empirical formula for pollutant emissions with different headway gains is applied in the mixed traffic. A series of microsimulations are tested based on the improved Full Velocity Difference (FVD) model and CAV models which are established as discrete steps based on the above analyses. The simulation results are highly consistent with the theoretical analyses, demonstrating the universality of this model. Finally, it indicated that the overall optimal size of CAV platoons is between 5 and 10 when taking both the road capacity and pollutant emissions into consideration. • Connected and Automated vehicle. • Mixed traffic flow. • Capacity model. • Pollutant. • Emissions.