Safe Transportation Research & Education Center

Pedestrian and bicyclist injury and mortality is a common occurrence in California. Data from the Transportation Injury Mapping System found that serious injuries among bicyclists and pedestrians increased between 2017-2019, with 3,174 recorded in 2017 and a peak of 3,495 serious injuries in 2019. Along with serious injuries, there has also been an increase in mortality among these active transportation options reported by the National Highway Traffic Safety Association, which recorded 940 fatalities in 2017, and an increase to 972 by the end of 2019. One of the strategies that has been shown to be effective in reducing traffic injury is the implementation of road diets, which are also known as road reconfigurations, road re-chanellizations, road reallocations, or lane reductions. This intervention is a popular tool for city planners to improve the safety for bicyclists and pedestrians on high capacity roads at low costs. Burden and Largeway (1999) refer to road diets as “right-sizing” of roads because they reallocate the existing right-of-way to better support all transportation modes, including biking and walking. A large majority of interventions involve converting four-lane undivided roads into three lanes, one lane going each direction and one turning lane in the middle. Along with this lane reduction, many recent road diet projects involve utilizing the extra space provided to add new bike lanes, sidewalks, on-street parking, wider shoulders or concrete center islands.