Caltrans LTAP Center
Road Diets (Roadway Reconfiguration)
Figure 1: City of Fresno, Divisadero Street

WHAT IS THE COUNTERMEASURE?

The classic roadway reconfiguration, commonly referred to as a “road diet”, involves converting an undivided four-lane roadway into three lanes made up of two through lanes and a center two-way left turn lane. The reduction of lanes allows the roadway to be reallocated for other uses such as bike lanes, pedestrian crossing islands, and/or parking. Road diets have multiple safety and operational benefits for vehicles as well as pedestrians, such as:

  • Decreasing vehicle travel lanes for pedestrians to cross, therefore reducing the multiple-threat crash (when one vehicle stops for a pedestrian in a travel lane on a multilane road, but the motorist in the next lane does not, resulting in a crash) for pedestrians,
  • Providing room for a pedestrian crossing island,
  • Improving safety for bicyclists when bike lanes are added (such lanes also create a buffer space between pedestrians and vehicles),
  • Providing the opportunity for on-street parking (also a buffer between pedestrians and vehicles),
  • Reducing rear-end and side-swipe crashes, and
  • Improving speed limit compliance and decreasing crash severity when crashes do occur.
Figure 2: City of San Diego, La Jolla / Bird Rock

Road diets’ safety effectiveness depends on the context they are applied in. Based on FHWA Turner-Fairbank Highway Research Center’s studies, road diets may reduce crashes by 19-47 percent, depending on what is involved in the road diet (i.e., roundabouts, pedestrian refuge islands, on-street parking, etc.) and effectiveness of access control along the roadway segment where the road diet is applied.

WHAT HAVE WE DONE SO FAR?

The FHWA California Division, in conjunction with the Resource Center, has provided workshops on road diets to our four Focus Cities in pedestrian safety and presented to the Caltrans Traffic Safety Steering Committee on two road diets recently applied to State Routes going through residential neighborhoods of downtown San Francisco. As a result of our efforts, the Cities of Pasadena and Fresno have recently developed websites for providing basic public information on road diets proposed in their jurisdictions:

Figure 3: City of Pasadena, Cordova Street

WHERE DO WE WANT TO GO? – SUCCESSFUL PRACTICES, LESSONS LEARNED, POINTERS FOR IMPLEMENTATION

Road diets have become an EDC 3 initiative and we anticipate developing a more robust roll-out strategy in conjunction with Caltrans Divisions of Transportation Planning, Design, Traffic Operations and Local Assistance. Since most road diets, even those proposed on the state highway system, are typically initiated by local agencies, we also anticipate a key role the new LTAP center can play in outreach to local agencies.

Download this Proven Safety Countermeasure (PDF)