Optimal Variable Speed Limit Control under Connected Work Zone and Connected Vehicle Environment

Despite the long-term benefits gained through road maintenance projects, the work zone involved can cause serious traffic congestion and greatly increase traffic delay. Variable speed limit (VSL) enforcement provides a means to reduce the travel time and alleviate the traffic congestion in work zones. This paper presents a novel proactive VSL control algorithm for freeway work zone traffic management under connected work zone and connected vehicle environment. In a connected work zone environment, the estimated work zone capacity can be easily shared considering the work zone configuration factors such as number of lane closure, signal distance, presence of work activity, etc. After incorporating the estimated capacity which contributes to a better modeling of the traffic disturbance caused by work zone, the traffic flow predictive model was established to obtain preventive measures and avoid traffic breakdown. In addition, based on the trajectories of individual vehicles recorded and shared by connected vehicles, the objective function was developed for the VSL control algorithm to minimize the Total Travel Time which can be used to measure level of the traffic congestion. The VSL control was implemented and tested in a traffic simulator SUMO. The results showed that the designed VSL algorithm effectively decreased the total travel time with the reduction of the speed variance which potentially improved the traffic safety at work zones.