The purpose of this course is to provide information on the most common road diet which involves converting an existing four-lane undivided roadway segment to a three-lane segment consisting of two through lanes and center two-way, left-turn lane (TWLTL). Road diets can be used to address safety concerns with four-lane undivided highways associated with relatively high crash rates. The reduction of lanes allows the roadway cross section to be reallocated for other uses such as bike lanes, pedestrian refuge islands or parking.
The benefits of road diets include improved safety, traffic calming and the opportunity to repurpose segments of the roadway to create on-street parking, bike lanes or transit stops. Based on the history of safety studies, designers can expect a crash reduction of 19 to 47 percent after installing a road diet.