ENGINEERING COUNTERMEASURES TO REDUCE RED-LIGHT-RUNNING

Abstract

Red-light-running is a significant problem throughout the United States and Texas. It is associated with frequent and severe crashes. Engineering countermeasures represent a useful means of combating the red-light-running problem because they are passively applied (in contrast to enforcement countermeasures which are considered to be overt and punitive) and are in the direct control of the agency responsible for the signal. The objective of this research project was to describe how engineering countermeasures can be used to minimize the frequency of red-light-running and associated crashes at intersections. This report documents the work performed, findings, and conclusions reached as a result of a two-year research project. During the first year, engineering countermeasures were identified and implemented at 10 intersections in five Texas cities. Before-after studies of red-light-running frequency were then conducted at each intersection. Also, the three-year crash history for each intersection was compared to its observed frequency of red-light-running. The findings from these studies indicate that the frequency of red-light-running decreases in a predictable way with decreasing approach flow rate, longer clearance path lengths, longer headways, and longer yellow interval durations. The crash data analyses indicate that right-angle crashes increase exponentially with an increasing frequency of red-light-running. Models for computing an intersection approach's red-light-running frequency and related crash rate are described. Guidelines for selecting appropriate engineering countermeasures and evaluating their performance are provided.