Driver Response to Automated Speed Enforcement on Rural Highways in China

The primary objective of the present study was to identify how automated speed enforcement (ASE) affected the speeds that drivers choose on rural highways. The study specifically sought answers to the following two questions: (a) How did drivers respond to ASE on rural highways where live speed enforcement is limited? (b) What was the spatial extent of the speed reduction effects of ASE on rural highways? The research team compared speed data collected at various distances from seven sites in the Nanjing area of China where speed cameras were deployed. It was found that ASE significantly reduced vehicle speeds and speed violations in the vicinity of the locations where the speed cameras were deployed. However, ASE was not an effective way to reduce vehicle speeds on road sections beyond the area of influence of the speed cameras. The speed profiles developed in this study showed that the area of influence of a speed camera on a rural highway was generally less than 1 km. Drivers usually started to decelerate about 300 to 400 m before the speed cameras and recovered their original speeds about 300 to 400 m after the speed cameras. The findings suggested that without supplementation with other live speed enforcement efforts, such as mobile or stationary police patrols, elimination of speed violations on rural highways by the use of ASE alone would be difficult. A more realistic solution would be to deploy speed cameras at preselected potentially hazardous locations, such as intersections and horizontal curves, to help reduce speed violations.