Model predictive control for variable speed limit in freeway work zone

A new model for variable speed limit in freeway work zone was presented. Model predictive control was applied to optimizing variable speed limit in freeway work zone. The classic macroscopic traffic model METANET was a little modified for simulating the traffic in the work zone, considering the effect of speed limit. One new optimization model for solving the optimal variable speed was proposed, which is a real-time nonlinear controlling model. In the optimization model, the objective function considers efficiency and safety by minimizing the total time spent (TTS) and the speed variation. To solve this optimization model, discretization for time horizon was conducted firstly; on every control time step, SQP algorithm was applied to solve the nonlinear programming in the next; the optimization results were integer conversion for the real speed limit displayed. One example was conducted to prove the efficiency of the proposed model. And some valuable conclusion was obtained.