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Publication Number:  FHWA-HRT-17-078     Date:  November 2017
Publication Number: FHWA-HRT-17-078
Date: November 2017


Safety Evaluation of Red-Light Indicator Lights (RLILs)

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FHWA Publication No.: FHWA-HRT-17-078
FHWA Contact: Roya Amjadi, HRDS-20, (202) 493-3383, roya.amjadi@dot.gov

This document is a technical summary of the Federal Highway Administration report Safety Evaluation of Red-Light Indicator Lights (RLILs) (FHWA-HRT-17-077).


The Federal Highway Administration (FHWA) established the Development of Crash Modification Factors (DCMF) program in 2012 to address highway safety research needs for evaluating new and innovative safety strategies (improvements) by developing reliable quantitative estimates of their effectiveness in reducing crashes. The goal of the DCMF program is to save lives by identifying new safety strategies that effectively reduce crashes and promote those strategies for nationwide implementation by providing measures of their safety effectiveness and benefit–cost (B/C) ratios through research. State transportation departments and other transportation agencies need to have objective measures for safety effectiveness and B/C ratios before investing in broad applications of new strategies for safety improvements. Forty State transportation departments provide technical feedback on safety improvements to the DCMF program and implement new safety improvements to facilitate evaluations. These States are members of the Evaluation of Low-Cost Safety Improvements Pooled Fund Study, which functions under the DCMF program.

This study investigated the safety effectiveness of red-light indicator lights (RLILs). This effort was 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 and educate drivers about the existence and purpose of RLILs.

Few studies have explored the safety effectiveness of RLILs; specifically, studies have not shown the crash-based safety effectiveness for four-legged intersections. This study sought to fill this knowledge gap.

FHWA-HRT-17-078 PDF Cover Image



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