Study Details

Study Title: Safety Evaluation of Red-Light Indicator Lights in Florida

Authors: Himes et al.

Publication Date: JAN, 2017

Abstract: Red-Light Indicator Lights (RLILs) are auxiliary lights mounted on signal heads, mast arms, or poles and directly connected to a traffic-control signal. The RLIL activates at the onset of the red phase and allows an enforcement officer to observe red-light running from downstream of the intersection. This strategy is intended to reduce the frequency of crashes resulting from drivers disobeying traffic signals by providing a safer and more efficient means for police to enforce the red interval. Geometric, traffic, and crash data were obtained at treated four-leg signalized intersections in Florida. To account for potential selection bias and regression-to-the-mean, an empirical Bayes (EB) before-after analysis was conducted, utilizing reference groups of untreated four-leg signalized intersections with similar characteristics to the treated sites. The analysis also controls for changes in traffic volumes over time and time trends in crash counts unrelated to the treatment. Results indicate statistically significant crash reductions for most crash types. Disobeyed signal crashes have an estimated crash modification factor (CMF) of 0.71. Total crashes, fatal and injury crashes, right-angle, and left-turn crashes have estimated CMFs of 0.94, 0.86, 0.91, and 0.60, respectively. The benefit-cost ratio estimated with conservative cost and service life assumptions is 92:1 for four-leg signalized intersections. The results suggest that the treatment, even with conservative assumptions on cost, service life, and the value of a statistical life, can be cost effective. In addition to the crash-related benefits, RLILs can improve the efficiency and safety of red-light running enforcement efforts. While this study did not evaluate the efficiency and safety impacts with respect to enforcement, it should be noted that RLILs do allow police to observe violators from a downstream position, eliminating the need for a second observer (upstream) and the need to pursue a violator through the red-light.

Study Citation: Himes, S., F. Gross, B. Persaud, and K. Eccles. "Safety Evaluation of Red-Light Indicator Lights (RLILs) at Intersections". Federal Highway Administration, Report FHWA-HRT-17-077, Washington, D.C. (November 2017).

Related Citations: Himes, S., F. Gross, K. Eccles, and B. Persaud. "Safety Evaluation of Red-Light Indicator Lights in Florida". Presented at the 86th Annual Meeting of the Transportation Research Board, Paper No. 17-03500, Washington, D.C., (2017).

Study Report: Download the Study Report Document


CMFs Associated With This Study

Category: Advanced technology and ITS

Countermeasure: Install Red-light indicator lights

CMF CRF(%) Quality Crash Type Crash Severity Roadway Type Area Type
0.939 6.1 4 Stars All All Not specified Not specified
0.856 14.4 4 Stars All K,A,B,C Not specified Not specified
0.905 9.5 4 Stars Angle All Not specified Not specified
0.6 40 4 Stars Left turn All Not specified Not specified
1.016 -1.6 4 Stars Rear end All Not specified Not specified
0.713 28.7 4 Stars Other All Not specified Not specified
0.892 10.8 4 Stars Nighttime All Not specified Not specified
1.024 -2.4 3 Stars All All Not specified Not specified
0.963 3.7 3 Stars All All Not specified Not specified
0.939 6.1 3 Stars All All Not specified Not specified
0.736 26.4 3 Stars All All Not specified Not specified
0.995 0.5 3 Stars All All Not specified Not specified
0.934 6.6 3 Stars All All Not specified Not specified
0.917 8.3 3 Stars All K,A,B,C Not specified Not specified
0.888 11.2 3 Stars All K,A,B,C Not specified Not specified
0.856 14.4 3 Stars All K,A,B,C Not specified Not specified
0.676 32.4 3 Stars All K,A,B,C Not specified Not specified
0.895 10.5 3 Stars All K,A,B,C Not specified Not specified
0.868 13.2 3 Stars All K,A,B,C Not specified Not specified
0.989 1.1 3 Stars Angle All Not specified Not specified
0.944 5.6 3 Stars Angle All Not specified Not specified
0.905 9.5 3 Stars Angle All Not specified Not specified
0.756 24.4 3 Stars Angle All Not specified Not specified
1.036 -3.6 3 Stars Angle All Not specified Not specified
0.856 14.4 3 Stars Angle All Not specified Not specified
0.748 25.2 3 Stars Other All Not specified Not specified
0.784 21.6 3 Stars Other All Not specified Not specified
0.713 28.7 3 Stars Other All Not specified Not specified
0.368 63.2 3 Stars Other All Not specified Not specified
0.797 20.3 3 Stars Other All Not specified Not specified
0.75 25 3 Stars Other All Not specified Not specified
0.749 25.1 3 Stars All All Not specified Not specified
1.018 -1.8 3 Stars All All Not specified Not specified
0.858 14.2 3 Stars All All Not specified Not specified
0.969 3.1 3 Stars All All Not specified Not specified
0.716 28.4 3 Stars All K,A,B,C Not specified Not specified
0.916 8.4 3 Stars All K,A,B,C Not specified Not specified
0.813 18.7 3 Stars All K,A,B,C Not specified Not specified
0.873 12.7 3 Stars All K,A,B,C Not specified Not specified
0.749 25.1 3 Stars Angle All Not specified Not specified
0.978 2.2 3 Stars Angle All Not specified Not specified
0.882 11.8 3 Stars Angle All Not specified Not specified
0.913 8.7 3 Stars Angle All Not specified Not specified
0.911 8.9 3 Stars Other All Not specified Not specified
0.608 39.2 3 Stars Other All Not specified Not specified
0.899 10.1 3 Stars Other All Not specified Not specified
0.614 38.6 3 Stars Other All Not specified Not specified