Dynamic congestion toll pricing strategies to evaluate the potential of route-demand diversion on toll facilities

Abstract

Congestion pricing has been proved to be an effective traffic management measure to reduce traffic congestion in metropolitan regions. Its aim is to limit the access of traffic towards heavily congested areas, thus to force road users to shift to other means of transportation by imposing toll fares to the vehicles willing to access these areas. Previous urban congestion pricing schemes have been efficiently discouraging individual vehicles from accessing congested areas by reducing traffic and mitigating environmental emissions. This study presents a new methodology for a dynamic zone-based congestion pricing system in networks with heterogeneous users, where the variable fares are calculated based on traffic congestion and environmental emission indicators. Congestion pricing methodology aims to determine optimal toll fares based on traffic congestion, vehicle type, and emissions produced based on the London Emission Model (LEM) to ensure reduction of emissions in the network-wide level. Further, methodology is developed within Dynamic Traffic Assignment (DTA) framework with a microscopic simulation model, that enables behavioral adaptation of the drivers during the pricing period as well as realistic congestion propagation. The performance of the proposed methodology is evaluated against a potential fixed pricing scheme in a Leicester city network, with 9652 sections, 3757 nodes where pricing policy area covers four zones with radius of 1.5 km from the centre. Simulation outputs have shown decrease in traffic delay time and NOx emissions within the cordon area where the congestion pricing policy is applied. However, further strategic traffic management improvements are required to control the mode shift phenomena in the boundary area produced by the congestion policy.