Environmental impact of autonomous cars considering platooning with buses in urban scenarios

Platooning is an essential strategy for exploiting the benefits of connected and autonomous vehicles (CAV). Quantitative research is needed to understand the factors of influence, evaluation indicators, and analytical granularity of the environmental impacts of platooning fully. This study was performed to estimate the energy consumption and emissions impacts of platooning from an aerodynamics perspective under complex urban road conditions using low-cost methodology. Speed, acceleration, spacing, platoon composition, and vehicle position were analyzed. An aerodynamic analysis platform was established based on the lattice Boltzmann method (LBM). Energy and emissions models were developed based on vehicle specific power (VSP) to establish a mapping relationship between operating and environmental impacts. An impact estimation method based on the LBM and VSP is proposed. Vehicle test data were collected for a case study, and multiple scenarios were analyzed. The results show that high speed, low acceleration, and small spacing can improve the environmental benefits of platooning. The most significant benefits were achieved in the following vehicle position of the Bus-Car platoon scenario, with a maximum energy reduction rate of 61.26 % and a maximum emissions reduction of 56.23 %. The study contributes to designing management strategies and trajectory optimization considering the environmental benefits of platooning.