Approximation to Optimal Dynamic Traffic Assignment of Peak Period Traffic to a Congested City Network

We present a vehicle-by-vehicle deterministic queueing traffic assignment model for minimising total travel delay in a congested road network. The model routes drivers, one at a time, according to the marginal delay of each link. This is regarded as a combination of the delay caused by each driver to others travelling in the whole network, and the travel delay experienced by the driver himself. This yields an approximate system optimal routeing pattern and the corresponding road prices needed to cause the user equilibrium traffic pattern, which would arise from each driver minimising only his own travel delays, to be the approximate system optimal one. A key characteristic of the model presented is that it is applicable to (multi-commodity) networks having many origin-destination pairs and many bottlenecks. The model has evolved as a result of the initial study on this problem in Ghali and Smith [1], and basically extends the model in that paper. Computational results comparing network performance of applying the model of this paper against that of the previous paper as well as against network performance due to the natural user equilibrium networks are provided.