One tool that planners and engineers use to improve the safety and functioning of roads for all users – especially pedestrians and bicyclists – is the “road diet.”  A road diet narrows or eliminates travel lanes on a roadway in order to make more room for pedestrians and bicyclists, manage speed, and/or improve overall traffic flow.  General information on road diets can be found at on the Pedestrian and Bicycle Information Center (PBIC) website and in “Lesson 15: Bicycle Lanes” in the Federal Highway Administration’s (FHWA) University Course on Bicycle and Pedestrian Transportation.

FHWA’s Highway Safety Information System (HSIS) recently released a summary report evaluating the effects of “road diet” treatments on crashes and injuries.   This report updates and replaces an earlier report (FHWA-HRT-04-082) on the same topic.  The treatment studied was the reduction from four lanes to three.  The report concludes that such road diets can result in a 19 to 47 percent reduction in crashes, depending on context and site characteristics.