Direct left turn at intersections increases delays and causes more accidents in certain conditions. Permissive-only left turn may cause safety problem because drivers have to find a suitable gap to go through the opposite go-straight flow. Vehicles in protected-only left turn lane may block the vehicles in go-straight lane, which results in larger overall delays.
The research aims to analyze which left turns should be prohibited in a city network due to safety and efficiency. The respective optimization will therefore minimize both travel times and the number of left turns in the road network. In order to obtain the criteria of the objective function a traffic demand and a traffic flow model need to be integrated in an optimization algorithm. The optimization will take into account the requirements of signal control programs for all traffic modes, such as realistic minimum green, maximum red and safe intergreen times. The results will provide suggestions for urban traffic management.
Researcher: Qinrui Tang, M.Sc.