A flexible model-free tram signal priority method with a large coordination scope in China

Tram systems with the advantages of reliable operation, comfort, low emissions, and moderate capacity have been quite popular in recent years in China. However, there are still problems with tram signal control (e.g. evaluation model, signal control strategies). In-depth analysis on existing operational issues of trams, calculation of two evaluation indexes, as well as a flexible model-free tram signal priority method, were developed to deal with tram problems. Empirical research in Songjiang District, Shanghai, shows that: (1) Function of green extension strategy is limited with c.a.10% tram priority improvement, while the optimal one can reach to 85% even higher in average. (2) The scheme with the benefit of trams but no negative impacts, even benefits on general traffic can be realized. (3)Optimal solution is beneficial for intersections with maximum c.a.70% melioration with delay decreasing from 132.7 s/vehicle to 40.89 s/vehicle, or from 104.77 s/capita to 22.31 s/capita. This paper has great significance for signal optimization and safety of tram systems, even the development of a comprehensive transportation system for a city.