Providing public transport priority in the perimeter of urban networks: A bimodal strategy

Bimodal urban networks are complex systems operating within multiple constraints. This paper develops an integrated and systematic framework for the optimization of bimodal urban networks using 3D-MFDs, considering the complexities of bimodality. With the proposed framework, effective strategies can be designed for the planning, management, and control of bimodal networks. In particular, strategies to provide public transport priority on the network level can be holistically evaluated. We apply this methodological framework to propose, model, and analyze one such strategy to provide public transport priority in the perimeter of urban networks. The proposed strategy addresses a pressing problem of the existing perimeter control (i.e. gating) schemes: public transport vehicles will be queuing with the cars in the perimeter and hence blocked from entering the network. This impairs the service quality of public transport. Adopting our proposed strategy, the inflows of public transport and cars can be regulated independently (i.e. both inflows are controllable), the network traffic can be managed more efficiently, and public transport priority can be provided. The performance of the proposed strategy is evaluated both analytically and with simulations. Results show that the proposed strategy always performs better than existing perimeter control schemes in terms of passenger mobility. Most importantly, it differentiates the public transport mode and the car mode, with much smaller queueing time outside the network for public transport. This can shift the transportation system to a more sustainable state in the long run. Policy recommendations are provided for a large range of traffic scenarios.