An integrated roadway controller and its evaluation by microscopic simulator VISSIM

A roadway control system that integrates variable speed limits and ramp metering is designed to relieve congestion, suppress shock waves and improve safety on a freeway stretch. The speed control design is only based on the fundamental flow density relationship and can be easily implemented in real-time applications. In order to closely evaluate the effectiveness and robustness of the controller on a real transportation network, a microscopic traffic simulation model is implemented, which can capture a greater level of details of the network. This model is constructed based on the Berkeley Highway Laboratory (BHL) and is validated with field data. Simulations of different congestion scenarios show that the designed roadway control system reduces congestion and improves freeway efficiency.