A road diet is a technique in transportation planning that involves reducing the number of travel lanes and/or effective width of the road to achieve systemic improvements. The most common application of a road diet is to improve safety or provide space for other modes of travel. Here are some key features of a road diet:

• Lane reduction: A typical road diet technique is to reduce the number of lanes on a roadway cross-section. For example, a two-way, four-lane road might be reduced to one travel lane in each direction.

• Center turn lane: A center turn lane or flush traffic median for turning traffic may be added.

• Pedestrian and bicycle infrastructure: The freed-up space from lane reduction can be used to add or widen footpaths/sidewalks, boulevards (landscaping strips), cycle lanes on one or both sides of the road, reserved tram tracks, pedestrian refuge islands, on-street parking, or transit stops.

• Traffic calming: Road diets can lead to more consistent speeds and a more community-focused, Complete Streets environment that better accommodates the needs of all road users.

Road diets can be a low-cost safety solution when planned in conjunction with a simple pavement overlay, and the reconfiguration can be accomplished at no additional cost. If properly designed, traffic does not divert to other streets after a road diet, because the road previously provided excessive capacity. Before-and-after studies of road diet projects have given the Federal Highway Administration and local transportation departments the confidence to declare it a cheap way to reduce vehicle collisions and make roads more bike and pedestrian friendly.