Informational Guide on Road Diets and Other Roadway Reconfigurations

Project status


Start date: 09/13/12
End date: 12/31/14


Principal investigators:

About the research

A classic Road Diet converts an existing four-lane undivided roadway segment to a three-lane segment consisting of two through lanes and a center two-way left turn lane (TWLTL). A Road Diet improves safety by including a protected left-turn lane for mid-block left-turning motorists, reducing crossing distance for pedestrians, and reducing travel speeds that decrease crash severity. Additionally, the Road Diet provides an opportunity to allocate excess roadway width to other purposes, including bicycle lanes, on-street parking, or transit stops. This Informational Guide includes safety, operational, and quality of life considerations from research and practice, and guides readers through the decision-making process to determine if Road Diets are a good fit for a certain corridor. It also provides design guidance and encourages post-implementation evaluation.


Report: Road Diet Informational Guide (NA pdf) November 2014


Sponsor(s): Federal Highway Administration Office of Safety

Partner(s): Sub with Sam Schwartz Engineering and U of Utah to Leidos