Congested networks are a serious problem in urban sites. To increase the effective use of the overall capacity of urban street networks and to inhibit oversaturation the European project COSMOS develops new congestion management strategies. The means for those strategies are rerouting via VMS interacting with dynamic signal control. Within the project a test site is established in the Greek harbour town Piraeus. This test site has its specific problems with a large amount of traffic going through the city to access the ferry boats. In this paper the potential of a coordinated control scheme in scenarios near or beyond saturation are presented by simulation. The use of rerouting via VMS diverts traffic flows, and, by that, influences the signal control to reflect the change of flows in the duration of green time for the alternative routes used for rerouting. As an approach to visualise the effects from rerouting and dynamic signal control, a macroscopic dynamic traffic flow simulator is used. In addition, the simulator periodically calculates the travel times on different routes and uses these results to determine a new set of rerouting recommendations. An acceptance rate for those recommendations is assumed and new traffic flows are calculated. Effectiveness of this coordinated control scheme is performed using travel times on relevant routes in the network. In the paper the effects of this control scheme are demonstrated by applying it to the topology and specific problems of the harbour town Piraeus.
Samenvatting