Evaluation of the Intersection Confirmation Light With Targeted Enforcement to Reduce Red Light Running Violations at Freeway Ramp Intersections

Abstract

ABSTRACT Red Light Running (RLR) at signalized intersections continues to be a safety concern for many communities in the United States. The Insurance Institute for Highway Safety (IIHS) reported a total of 683 fatalities and 133,000 injuries in 2012 due to crashes involving RLR. There are many strategies to mitigate RLR violations that can be classified as engineering, enforcement, or education techniques. Previous studies have reported positive impacts of these strategies in reducing RLR. Intersection confirmation lights with targeted enforcement are a low-cost measure to reduce RLR in communities where automated enforcement is not practical or feasible. Some studies have shown the effectiveness of confirmation lights in reducing RLR at four-leg signalized intersections. This research study focuses on evaluating confirmation lights to enhance enforcement at on-ramp signalized intersections. Operations of on-ramp intersections are different than four-leg intersections, as the drivers may be more likely to run the red light and join the freeway. Police officers find these intersections difficult to enforce from the ramp as they cannot see the traffic signals. Adding confirmation lights can change that. Confirmation lights were deployed at two on-ramp intersections in Overland Park, Kansas. Traffic were observed at the treatment sites, and at five other control intersections. Traffic data were recorded before deployment, one month after, and three months after installation of the confirmation lights. A total of seven intersections were recorded for 24 hours on Tuesdays, Wednesdays, and Thursdays for a total of 1512 hours of traffic video. A z-test of proportions was used to determine if the changes in RLR violation rates from the before period to the after periods were statistically significant at the 0.05 level of significance. Violation time into red (how long it took a driver to run a red light after the red signal indication) was used as a secondary performance measure to evaluate the confirmation lights. A chi-square test of independence was used to analyze the violation times into red at the 0.05 level of significance. Analysis showed a 60.4 percent reduction in the RLR violation rate at the treatment sites and a 31.8 percent reduction at the control sites one month after installation of the confirmation lights. The three months after study indicated a 56.9 percent decrease in violation rates at the treatment sites and 60.16 percent reduction at the control sites. At the 0.05 level of significance, the one month and three month reductions at the treatment sites were statistically significant whereas only the three months reduction were statistically significant at the control sites. A chi- square test was conducted for time into red which was statistically significant for the one month and three month violations for both the treatment and the control sites. This indicates a relationship between confirmation lights with targeted enforcement and the driver behavior for time into red. It should be noted that, the confirmation lights were not visible to the driver, however the driver could see the police officer located on the on-ramp. Reduction in RLR violation rates were observed at control site. A chi-square test for goodness of fit was performed on data obtained from Overland Park Police Department on the number of officers deployed and citations written to check if the structure of enforcement changed during after study period causing reduction of violation rates at the control sites. It was found at the treatment sites that less number of officers were deployed during after study period and less citations were made in after study period compared to before study period. At the control sites, it was found that less officers were deployed during after study period compared to before study period, however the change in citations made were statistically not significant during both study periods. Hence the reductions at the control sites could be a possible halo effect from treatment sites effectively converting the control sites to spillover sites. In conclusion, the findings of this research study indicated that confirmation lights with targeted enforcement have a positive effect in reducing RLR violations at on-ramp signalized intersection.