Traffic performance and road space allocation in multimodal urban networks with an MFD representation

Abstract

This paper investigates traffic performance of multimodal urban networks with a multimodal Macroscopic Fundamental Diagram (mMFD) model and sheds light on how space allocation across modes (with attention to mixed and dedicated lanes), influences the performance of the whole network. The 3D-MFD, as the representation of a bimodal case of mMFD, relates the accumulation of two modes of transportation vehicles, which compete for limited space, to the traffic production, and it assesses the overall capacity of the network. By employing different networks with diverse lane allocation structures, the authors carry out extensive analysis on the properties of the 3D-MFD with insightful comparisons via micro-simulation of the city of Zurich, the city of San Francisco, and a set of abstract grid networks. Simultaneously, taking advantage of the simulation model, the authors create various network lane allocation layouts (the data of which are typically difficult to collect in the field), and evaluate the performance of dedicated bus lanes versus mixed lanes. Furthermore, the authors implement different space allocation percentages in the abstract grid network in order to provide comparable network structures. An analytical optimization model is carried out for the grid network, to estimate the optimal space allocation from a passenger mobility perspective and to validate the results obtained from the micro-simulation.