A road diet is a reallocation of road space involving a reduction in the number of travel lanes. Remaining existing road space can be used for parking, landscaping, bicycle lanes, pedestrian facilities, or any combination of these. Road dieting generally creates a reduction in vehicle speeds and collisions, and encourages sustainable travel modes. In determining the safety benefits of road diets for the Insurance Corporation of British Columbia (ICBC), the provincial crown insurer, and whether it may wish to give qualified support to road diet projects that meet identified success factors, Opus International Consultants reviewed academic literature, journal articles, and various stakeholder publications, from which the benefits of, and best practices for implementation of road diets were identified. Benefits identified through the review included: collision and speed reductions; maintenance of capacity; increased safety and comfort for pedestrians and cyclists; other benefits such as low cost of implementation and improved driveway/access safety. Six recent road diet projects in British Columbia from Coquitlam, Esquimalt, Kamloops, Prince George and Victoria, and corresponding nearby and faraway control sites were also identified. These sites were analyzed using simple Before and After methods, in addition to comparison with faraway controls. Collision reductions were generally observed, reductions of between 23 percent and 78 percent, largely overlapping with the reductions found in the literature of 6 percent to 62 percent. Victoria and Kamloops both experienced an increase in collision rate from the before period to the after period using these methods; however, site-specific issues at these locations may have contributed to the results. Based on the best practices identified in the literature review, and findings from the six road diet projects, a checklist with eight criteria was developed for potential road diet projects. Sites that meet most of the criteria – existing cross-section, traffic volume, access/driveway density, existing collision types, and others – are expected to be most successful in terms of ease of implementation, maintaining corridor function and improving safety.
