Global Versus Local MPC Algorithms in Freeway Traffic Control With Ramp Metering and Variable Speed Limits

This paper compares global and local model predictive control (MPC) algorithms in a traffic network controlled by intelligent transportation system (ITS) signals (ramp metering and variable speed limits). It will be shown that local techniques have a suboptimal behavior and that centralized techniques are difficult to implement in real time. To deal with this problem, a local MPC with only one communication cycle at each sampling time is proposed. This controller improves the local controller performance, and although it is suboptimal with regard to the centralized controller behavior, it can be implemented in real time.