Actual Speed Distribution vs. Speed Limit on Bo Sai Highway of Xinjiang Province in China

Speeding is one of the most prevalent factors contributing to traffic crashes. Speed limit is one of strategies to enforce traffic safety by controlling drivers' choices. This paper discusses the rationality of speed limit on Bosai highway in Xinjiang Province. In order to evaluate the rationality of speed limit, three studies sites were posted in vicinity of speed limit sign. Speed distributions inside and outside speed limit zone, crashes records and drivers' compliance were examined. Significance of speed differences are tested by independent t test. Results show that 100km/h speed limit for passenger cars is within drivers' expectation and 80km/h speed limit for commercial vehicles is unreasonably high. As to the safety impacts, there is no evidence supporting the relationship between crashes and speed limit due to the limited data. The checking process has a practical aspect for speed determination and optimal use of limited road resources.