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Federal Highway Administration Research and Technology
Coordinating, Developing, and Delivering Highway Transportation Innovations

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Publication Number:  FHWA-HRT-16-035    Date:  June 2016
Publication Number: FHWA-HRT-16-035
Date: June 2016


Safety Evaluation of Intersection Conflict Warning Systems

Chapter 2. Objective

This research examined the safety impacts of the application of ICWSs in Minnesota, Missouri, and North Carolina. The objective was to estimate the safety effectiveness of this strategy as measured by crash frequency. Target crash types included the following:

While the ICWS strategy specifically targets right-angle crashes, other crash types were considered to determine whether there were supplemental benefits or drawbacks. Rear-end crashes were the only additional crash type determined to occur commonly enough to be reasonably considered independently in the analysis. The research team surmised that there was potential for other drivers to be alerted in addition to the conflicting vehicles for which the systems were designed. This could lead to reductions in rear-end crashes on both the major and minor routes, owing to increased awareness. This would differentiate the outcome from the effects of traffic signals, which typically produce an increase in rear-end crashes while reducing right-angle crashes.

A further objective was to address questions of interest, such as whether effects varied depending on the following characteristics:

The evaluation of overall effectiveness also included the consideration of the installation costs and crash savings in terms of the B/C ratio.

Meeting these objectives placed some special requirements on the data collection and analysis tasks, including the need to do the following:



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