Impact of radical bike lane allocation on bi-modal urban road network traffic performance: A simulation case study

To decarbonize urban transport systems, promoting active modes by allocating more road space to cycling infrastructure to achieve a radical modal shift has become a popular transport policy. However, such policies usually receive strong public opposition due to the concern of traffic congestion caused by reduced road capacity for motorized traffic. From a traffic engineering perspective, this study first aims to answer the question “how much modal shift it requires to counterbalance the impact of road space reallocation on network traffic flow” by conducting a microscopic traffic simulation case study. The city center of Zurich together with the E-Bike City (EBC) network designed in Ballo et al. (2024) is selected for the case study. Through analyzing the changes in origin–destination travel times and network fundamental diagrams, it is first found that congestion level increases significantly in the EBC network with minimal modal shift due to the reduced queue storage space on the roads for cars. In comparison to the situation in the status-quo network, a policy goal of an over fifty percent modal shift is required to mitigate the negative impact on traffic performance. However, congestion can be completely prevented in the large modal shift scenario by better utilizing the capacity of the bike lane network. The findings showcase a possible transition pathway toward a sustainable urban road environment and its outcomes for policymakers. The proposed simulation and analysis framework can also be used by future studies with a similar objective.