Assessing the impacts of traffic calming at network level: A multimodal agent-based simulation

The reduction of speed limits in urban roads through traffic calming schemes intends to ensure safer traffic conditions among road users by reducing the probability related to the occurrence of severe accident. Looking it from a different perspective, traffic calming measures can potentially resolve congestion problems at the same time by lowering the overall accessibility and attractiveness of private cars in urban areas. This study proposes a new methodological approach to explore and assess the direct impacts of traffic calming in the transport system efficiency of a metropolitan area. The multi-agent transport simulation (MATSim) and Open-Berlin scenario are utilized to perform this simulation experiment. By developing a new external tool, the free flow speed and road capacity of each network link is updated based on new speed limits and different compliance rates, which are defined per road hierarchy level. The test scenarios that are formulated present radical conditions, where the speed limit in most urban roads of Berlin drops to 30 km/h or even 15 km/h. The findings of this study show a considerably high increase in trips, passenger hours, and passenger kilometers using public transport modes, when traffic calming links are introduced, the reserve change is observed in private cars trips. Although the speed limits are decreased in inner urban roads in most of the scenarios, the decrease of average travel speed of private cars is not so high as it was expected. Surprisingly, private cars are used for longer distances in all test scenarios. Car drivers seem to use already existed motorways and private road to commute. In simulations, driver compliance to the new speed limits seems to be a determinant factor that is strongly influenced by the design interventions applied in a traffic calming area.