Modelling Road Tolling in Dynamic Traffic Assignment (DTA): Preliminary Scoping

TRI-supported scoping project
Duration: October 2007 - September 2008

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In the past few decades, many congestion charging projects have been implemented around the world, including London congestion charging. These projects charge traffic only within one or few time intervals during a day other than throughout the day. Many of them only toll a fixed amount for use of a charging zone during a specified time interval. Some set a different constant toll for each of successive time intervals in the daytime, such as congestion charging in Singapore. One reported problem for these projects is that travellers depart earlier or leave later to avoid paying congestion charging tolls. Hence, two undesired peak periods have been observed. One is just before or around the start point of congestion charging and the other is just after or around the point when congestion charging stops. We term this type of jumps in travel demand caused by congestion charging boundary issues.

This project seeks to investigate the boundary issues in a bottleneck scenario using the DTA technique. and further seeks to utilise existing DUE (dynamic user equilibrium) algorithms to investigate their ability to incorporate tolling scenarios in network models. This project will investigate various tolling strategies under different assumptions and will seek to provide toll sets which reduce (or minimise) total network cost under these assumptions. The preliminary scoping work will concentrate primarily on a two-link network with a single OD pair.