Optimization of Variable Speed Limits for Efficient, Safe, and Sustainable Mobility

In an envisioned variable speed limit system, speed limits vary strategically and periodically in accordance with traffic and weather conditions to achieve better safety, efficiency, and enviromnental sustainability on a traffic network. For such a variable speed limit system, a three-objective, bi-level programming model is proposed to design optimal link-specific speed limits that minimize system travel time, number of expected accidents, and traffic exhaust emissions simultaneously for each specific strategic scenario. A solution framework is developed to solve the model that implements a nondominated sorting genetic algorithm and integrates various tools for performance evaluation. The proposed model and solution framework are demonstrated with the road network within the second ring road in Beijing