Coordination Concepts for Ramp Metering Control in a Freeway Network

The steadily increasing numbers and lengths of traffic jams on freeways have led to the application of Dynamic Traffic Management (DTM) measures all over the world. Ramp metering control has proven to be one of the most efficient means to reduce freeway congestion. Currently, it is expected that integrated and coordinated application of DTM measures will further improve its impact. This paper studies a coordinated ramp metering control algorithm called HERO/RWS. This algorithm has been developed for the current Dutch ramp metering systems and it will be applied on the Amsterdam A10 freeway network in the near future. The aim of this algorithm is to postpone congestion on freeways by effectively using ramp storage space from upstream on-ramps. VISSIM-based microscopic simulation results show that the HERO/RWS coordinated control outperforms non-coordinated ramp metering control. Parameter settings have been optimized for the specific A10-west network through a robustness study. In addition, the concept of coordination between ramp meter and upstream intersection traffic controllers is developed. The feasibility of this idea has been proven by a simulation study.