The Safety Effects Of Speed Cameras

With the development of social economy,the global level of motorization is constantly improving,and the number of traffic accidents is also increasing year by year.However,the driver’s illegal driving behavior,such as speeding,discretionary lane changing behaviors,is an important cause of road traffic accidents.In order to solve the safety problems caused by drivers’ overspeed behavior,governments of various countries have taken a number of safety measures,such as speed limit enforcement cameras.Speed camera enforcement is widely used to improve road safety at home and abroad,which can effectively control the occurrence of drivers speeding.However,due to the high cost of use and maintenance of speed cameras,there are some disputes about the effectiveness of speed cameras.This paper takes the UK,where the speed camera system is relatively mature,as an example to analyze the impact of speed cameras on road safety.In this paper,the influencing factors of traffic safety,the impact of traffic safety measures,the impact of speed camera and road safety evaluation methods are summarized.Then,the ‘‘Handbook of Rules and Guidance for the National Safety Camera Programme for England and Wales” is introduced,and speed camera sites selection criteria are expounded.Then,the Arc GIS software is used to extract the traffic accident data,traffic flow data,road network characteristics data,social economy and population data of the speed camera sites.Based on the data obtained,propensity score matching method and empirical Bayes method were used to evaluate the speed camera sites selection criteria.In addition,propensity score matching method and double robust estimation were used to evaluate the effective area of speed cameras and the impact of speed cameras on road accidents.The research results are as follows: first,the index of Multiple Deprivation,the proximity to school zones and residential neighborhoods,as well as population density,are the main considerations when selecting speed camera sites.Second,a site length of 500 m should be used to achieve the optimum safety effects of speed cameras when calculating the selection criteria.Third,speed cameras are most effective in reducing crashes when the requirement of minimum number of historical killed and seriously injured collisions(KSIs)is met and it is found that the speed cameras can obtain optimal effectiveness with a risk value greater than or equal to 30.Fourth,sites with multiple speed cameras perform better in reducing the absolute number of road accidents than those with a single camera.Fifth,speed camera sites are found to be most effective with a radius of 200 m and our results also suggest that multiple speed cameras are effective within a small radius(200 m and 300 m).