Analysis Method of Operating Freeway Speed Limit Value Optimization Based on Stopping Sight Distance

To address the problem of unreasonable speed limits on existing freeways, a model based on net-transverse distance, flat curve radius, and speed was established from the perspective of stopping sight distance. The model has been applied to the optimization of speed in the “Xing Gan Freeway North Extension” project. The reasonable speed limit value is obtained according to the model combined with the graphic design index. The traffic simulation software VISSIM is redeveloped from the micro level and combines with COM interface technology to simulate speed limit schemes. The trajectory file was imported into the SSAM for analysis. The speed standard deviation and traffic conflict rate are selected to evaluate different speed limit schemes. Compared with the actual speed limit value of 100 km/h, the speed standard deviation and traffic conflict rate reduced by 1.03% and 57% when the speed limit value was increased to 120 km/h.