Traffic conflict standards for intersections

TLDR

The study applies the traffic conflict technique to estimate and evaluate intersection safety, aiming to enhance its usefulness as a safety assessment tool. Using 94 conflict surveys, the authors established frequency and severity standards, developed an Intersection Conflict Index to summarize risk, and performed regression analysis to predict conflicts from traffic volume and accidents. The derived standards enable relative risk comparison across intersections; regression shows hourly conflict rates correlate with volume for both signalized and unsignalized intersections, while accident–conflict relationships hold only for signalized intersections, and a case study illustrates the method’s utility.

Abstract

This paper describes the application of the traffic conflict technique to estimate, traffic safety at intersections. Using data collected from 94 conflict surveys, traffic conflict frequency and severity standards for signalized and unsignalized intersections have been established. These standards allow for the relative comparison of the conflict risk at various intersections. An Intersection Conflict Index (ICI) measure was developed to summarize conflict risk and provide an indication regarding the relative risk of being involved in a conflict at an intersection. In addition, regression analysis was used to develop predictive models which relate the number of traffic conflicts to traffic volume and accidents. The regression analysis results indicate that: (i) the average hourly conflict rate (AHC) and the average hourly severe conflict rate (AHC 4+) correlated reasonably well with traffic volume for both signalized and unsignalized intersections, and (ii) strong relationships between accidents and conflicts were obtained for signalized intersections only. These research efforts are expected to further enhance the usefulness of the traffic conflict technique as a tool to evaluate the safety of intersections. Finally, a case study is presented as an example of the usefulness of traffic conflict analysis.