A. Hegyi, B. De Schutter, and J. Hellendoorn, "Optimal coordination of variable speed limits to suppress shock waves," Proceedings of the 42nd IEEE Conference on Decision and Control, Maui, Hawaii, pp. 2768-2773, Dec. 2003.
We present a model predictive control (MPC) approach to optimally coordinate variable speed limits for freeway traffic. In particular, we consider discrete-valued variable speed limits. Moreover, we also impose a safety constraint that prevents drivers from encountering speed limit drops larger than, say, 10 km/h. The control objective is to minimize the total time that vehicles spend in the network. This approach results in dynamic speed limits that reduce or even eliminate shock waves.