A. Hegyi, B. De Schutter, H. Hellendoorn, and T. van den Boom, "Optimal coordination of ramp metering and variable speed control - An MPC approach," Proceedings of the 2002 American Control Conference, Anchorage, Alaska, pp. 3600-3605, May 2002.
We present a model predictive control (MPC) approach to optimally coordinate variable speed limits and ramp metering for highway traffic. The basic idea is that speed limits can increase the range in which ramp metering is useful. The control objective is to minimize the total time that vehicles spend in the network. For the prediction of the evolution of the traffic flows in the network we use an adapted version of the METANET model that takes the variable speed limits into account. The coordinated control results in a network with less congestion, a higher outflow, and a lower total time spent. In addition, the receding horizon approach of MPC results in an adaptive, on-line control strategy that automatically takes changes in the system parameters into account.