Operating Speed and Highway Safety in China and the United States

Aimed at confusions on definition and application of operating speed,authors discussed concept of operating speed and its application in evaluating traffic operation through the field data collected at various highways in China.Particularly,authors compared the characteristics of operating speed in China and the United States in terms of distribution of operating speed, drivers' compliance of speed limit,and investigated why the differential operating speed between small and large vehicles in China was much bigger than that in the United States.Based on the analysis,authors presented a close correlation between differential speed and highway safety. Results show that the speed limit of a highway must be a function of several factors including the characteristics of distribution of operating speed.In order to enhance highway safety,authors recommend the lane separation for small and large vehicles under feasible conditions.