Effective safety improvements through low-cost treatments

A vast majority of traffic crashes in urban areas occur at signalized intersections. Roadway geometry, traffic control, adjacent land uses, and environmental factors at intersections often contribute to the high incidence of traffic crashes and injuries. A public-private partnership project to identify high-crash and high-risk locations in the city of Detroit was initiated in 1996. Eighteen candidate sites were selected, and an extensive engineering study was conducted to develop countermeasures to help alleviate the traffic crash problem at the selected sites. The Automobile Association of America, Michigan, was the private partner in this joint venture and, in partnership with the city of Detroit, was a major contributor to covering the cost of improvements. The selection of countermeasures was based on state-of-the-art methodology and analysis, and implementation of the selected countermeasures at some of the sites was undertaken as the initial phase of the project. A comprehensive before-and-after evaluation study was performed at three of the improved sites. The study revealed that the safety improvements that were implemented lowered both crash and severity experience. The differences between the before and after crash frequencies proved to be statistically significant. Additionally, a benefit-cost analysis at the study locations indicated extraordinary results. This research presents the evaluation study results and discusses the countermeasures and improvements that were the most successful in mitigating traffic crash problems at the selected study locations.