Integrated control of highway traffic flow

Abstract

Several efforts have been made during recent years on the control of traffic flow using ramp metering, variable speed limit and lane change control. Most of these techniques reported significant traffic mobility improvements in macroscopic simulations, which cannot be confirmed in some microscopic simulation cases. We demonstrate that the lack of travel time improvement is due to the forced lane changes at the bottleneck which introduce a capacity drop. In this paper, a lane change controller is proposed which provides lane change recommendations to avoid the capacity drop. Combined with the lane change control, a feedback linearisation variable speed limit controller which maintains the bottleneck flow at the maximum level and coordinates with ramp metering controllers is proposed. The integrated VSL, RM and LC controller can improve system performance, manage the ramp queues and maintain the fairness between mainline and on-ramp flows. Microscopic simulations show consistent improvements under different scenarios.