How to avoid free-riding in traffic emission control under regional heterogeneity: A game perspective

Road traffic emissions, characterized by cross-regional mobility, require collaborative inter-regional reduction efforts for sustainable transportation development. However, certain regions reduce their own abatement efforts by free-riding on emission control measures implemented by neighboring areas, thereby undermining collaborative governance. This study develops a tripartite evolutionary game model to investigate the strategic dynamics of inter-regional emission control under heterogeneous traffic emission conditions. The model explores the evolutionary interactions and strategic adaptations of the three involved stakeholders. Numerical simulations further reveal dynamic changes in strategic choices and identify the key factors influencing the evolutionary process. The results reveal a dual-impact mechanism of regulatory intensity between two regions with heterogeneous traffic emission. Notably, regions with limited emission reduction capacity tend to engage in free-riding, capitalizing on the abatement efforts of neighboring areas. Although inter-regional emission interaction intensity does not directly influence regulatory strategies, higher levels of connectivity significantly increase the risk of free-riding behavior. The optimal evolutionarily stable strategy combination is “positive emission reduction, positive emission reduction, and moderate regulation”, indicating that moderate regulation can enhance collaborative control of inter-regional traffic emissions. The system exhibits multi-path and multi-stage evolutionary trajectories, with regulatory costs, subsidy rates, and regional emission reduction capacities emerging as key determinants.