Effects of red light cameras on driver's stop/go decision: Assessing the green extension hypothesis

- A cross-sectional comparison of two groups of intersections with and without red light cameras (RLCs) is used.
- The likelihood of a driver stopping increased doubly in the presence of a RLC.
- Most drivers behaved in a less risky manner at RLC sites.
- The green extension is 0.5 s longer for non-RLC intersections.

A red light camera (RLC) offers a technological solution to the problematic behavior of motorists' tendency to run red lights, and decreasing potential crashes. To avoid committing violation in the presence of RLCs, some drivers stop abruptly, even if they could have crossed the line legally during the yellow change interval, leading to the reduction in entry time. In this study, the effect of RLCs on driver behavior was measured. Field data were collected at eight intersections in Lee County, Alabama: four with RLCs and four without RLCs. A total of 1613 traffic signal phases and 2391 drivers' response data was collected to estimate the amount of time that yellow change interval is typically used by drivers. Results revealed that the stopping behavior increased following the installation of RLCs. The green extension time at an intersection with RLCs was estimated to be one-half second shorter than at an intersection without RLC. The method applied in this study is informative for evaluating the effect of enforcement cameras on driver's behavior when the before RLC data is not available.