Study on Setting Speed Limits on Freeway and Arterial Highway

LOSS (Level of Service of Safety) is used to weigh the quality of safe operation that roads provide to the drivers and other traffic participants. Reasonable speed limit not only controls the speed of vehicles in appropriate range on the road, but also guarantees the traffic safety of the road. Crash rate was selected as a quantitative indicator, hierarchical standard of LOSS for freeway and arterial highway was studied, and then the LOSSs of freeway and arterial highway in China were divided into 4 levels. In virtue of the probability statistics, robust regression and on the basis of accident data, speed limit and geometric factors the accident prediction models were established. Based on the acceptable LOSS the method of setting speed limits about cars and trucks respectively was formed. The results would help traffic engineers in Chinese highway management departments choose right speed limits for freeway and arterial highway.