Impacts of time-varying cordon pricing: Validation and application of mesoscopic model for Stockholm

Abstract

This paper uses a simulation model to compare traffic and welfare effects of changes to the charging schedule currently in use in Stockholm. In particular, a step toll is compared to its flat counterpart at two charging levels. The increments between steps are also increased in a peaked step toll scenario. Furthermore, results from simulation of the current toll ring are compared to real-world measurements in a first attempt to validate model predictions regarding impacts of a time-varying congestion charging scheme. In the model, car users have the possibility to respond to congestion charging by changing departure time, route or switch to public transport and travel times are calculated using mesoscopic traffic simulation. Validation shows that departure time choice adjustments because of congestion charging are overestimated by the model that is based on stated preference data. This warrants further research on discrepancies between stated and revealed adjustments to congestion charging.The current step toll reaches the highest social benefit estimate in model predictions, but differences in traffic effects between the current step toll and its flat counterpart are rather small. Furthermore, results show that demand changes occur in the model to a considerably greater extent for trips with low value of time. The differences in welfare effects is for that reason large for different trip purposes, indicating the importance of accounting for heterogeneous trips when modelling effects of congestion charges.