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Reducing urban arterial intersection crashes through crash typing analysis: a case study

Retting, Richard A.; Farmer, Charles M.; Ferguson, Susan A.; Weinstein, Helen B.
ITE Journal
December 2006

Many crashes at specific locations on urban arterial streets occur in clusters of a particular type, and these often can be mitigated through traffic engineering countermeasures. To target engineering resources, it is important to identify locations where particular types of crashes frequently occur and where countermeasures likely to reduce them can be implemented. In the present study, the frequency of specific crash types were identified along an urban arterial in the Washington, D.C. metropolitan area. Engineering countermeasures were implemented at six locations with significant clusters of specific types of crashes. These included installation of protected left-turn signals, geometric changes to a merge lane, removal of a bus stop, and pavement markings to warn drivers of potential conflicts with right-turning vehicles. Results showed large reductions in the targeted crash types at the treated intersections. Across all types, crashes increased only 2% versus a 33% increase at the untreated intersections. This study provides evidence that intersections with excessive numbers of crashes of a particular type can be good candidates for relatively simple engineering countermeasures that reduce crashes.