Analysis of Red Light Violation Data Collected from Intersections Equipped with Red Light Photo Enforcement Cameras

This report presents results from an analysis of about 47,000 red light violation records collected from 11 intersections in the City of Sacramento, California, by red light photo enforcement cameras between May 1999 and June 2003. The goal of this analysis is to understand the correlation between red light violations and various driver, intersection, and environmental factors. Descriptive statistics suggest that younger drivers under 30 years of age are more likely to run red lights than drivers in other age groups. About 56 percent of the violators were traveling at or below the posted speed limit. Moreover, 94 percent of the violations occurred within 2 seconds after the onset of red light, and only 3 percent of the violations were recorded 5 seconds after the onset of red light. Approximately 4 percent of the violators were repeat offenders. Logistic regression modeling shows that the predicted odds of a younger driver running a red light at speeds greater than the speed limit is about 1.5 times the odds of a middle-aged driver. In addition, older drivers have a higher probability of running a red light when the elapsed time since the onset of red light is more than 2 seconds compared to younger drivers. Finally, red light violations rates are estimated between 6 and 29 violations per 100,000 intersection-crossing vehicles.