Integrated Ramp Metering and Mainstream Traffic Flow Control on Freeways Using Variable Speed Limits

In this paper we integrate local ramp metering (RM) with Mainstream Traffic Flow Control (MTFC) enabled via Variable Speed Limits (VSL), which is a recently proposed freeway traffic management tool. The integration is performed by the extension of an existing simple local cascade feedback MTFC controller via a split-range-like scheme. The integrated controller remains simple yet efficient and suitable for field implementation. The controller is evaluated in simulation and compared to stand-alone RM or MTFC via VSL, as well as optimal control results. The controller's performance is shown to meet the specifications and to approach the optimal control results for the investigated scenario.