Advance Warning Flashers: Do They Improve Safety?

Abstract

The main findings of a study to evaluate the safety of advance warning flashers (AWFs) are presented. A portion of the traffic accidents that occur at signalized intersections relate to poor driver decisions during the change interval time. Providing drivers with advance information about the status of a downstream traffic signal can help the driver make safer decisions. An AWF is a traffic warning device that can be used to provide such information to drivers. The study methodology is based on comparing the expected accident frequency at intersections with and without AWFs through the development of accident prediction models. The study used sample traffic volume, accident, and AWF data pertaining to 106 signalized intersections operated by the British Columbia Ministry of Transportation and Highways. The results from this study indicate that intersections equipped with AWFs have a lower frequency of accidents than similar locations without AWFs. However, the results indicate that this observed reduction in accident frequency, as correlated with AWF-equipped intersections, is not statistically significant at the 95 percent confidence level. Furthermore, a correlation has been found between the magnitude of the minor approach traffic volumes and the accident reduction capacity of AWFs. In this regard, it is observed that AWF benefits exist only for moderate to high minor approach traffic volumes.