Study Details

Study Title: Dynamic All-Red Extension – An Innovative Safety Countermeasure to Treat Red Light Running Crashes

Authors: Simpson

Publication Date:NOV, 2021

Abstract: The purpose of this project is to evaluate the safety effectiveness of Dynamic All-Red Extension (DARE) systems, also known as red clearance extension or dilemma zone protection systems. North Carolina Department of Transportation (NCDOT) has used DARE as an innovative safety countermeasure to combat red light running (RLR) crashes on the major road approaches of select rural, isolated traffic signals across the State since 2011. Sixteen intersections are included in the analysis. Crash modification factors (CMFs) are provided using Empirical Bayes (EB) before-after methodology. The DARE systems included in this study were implemented to target a specific crash type; therefore, the analysis conducted in this study is limited to frontal impact crashes (angle, left turn, right turn, and head on crashes) caused by a vehicle on a treated major road approach traveling through the intersection and running the red light. Although there is some variability in the magnitude and significance of the results among treatment groups, it appears there is generally a reduction in the frequency of target RLR crashes. The CMF using EB methodology is 0.93 (or a 7 percent reduction in target RLR crashes) for all sixteen treatment sites. Disaggregate analysis revealed the conditions under which the treatment appeared most effective and isolated sites that received DARE as the sole countermeasure intervention. The CMF using EB methodology for seven multilane at two-lane sites where DARE was the sole treatment is 0.65 (or a 35 percent reduction in target RLR crashes), which is statistically significant at the 95-percent confidence level. The benefit-cost ratio of the treatment is 143:1, which is realized due to low installation costs and high costs associated with RLR crashes. The treatment appears promising as a systemic safety treatment applied to isolated intersections with higher speed limits, especially for intersections with multilane major roads. Safety professionals should consider adding this safety countermeasure to the limited list of tools available to treat RLR crashes. DARE is inexpensive, provides demonstrated safety benefits, and past research shows it causes minimal delay in rural applications without creating driver habituation.

Study Citation: Simpson, C. "Dynamic All-Red Extension – An Innovative Safety Countermeasure to Treat Red Light Running Crashes." North Carolina Department of Transportation. Garner, North Carolina. (November 2021).


CMFs Associated With This Study

Category: Intersection traffic control

Countermeasure: Install Dynamic All-Red Extension (DARE)

CMF CRF(%)QualityCrash TypeCrash SeverityRoadway TypeArea Type
0.9373 StarsOtherAllAllRural
0.68323 StarsOtherAllAllRural
2.44-1443 StarsOtherAllAllRural