Reducing vehicle speeds: Traffic calming describes a set of road design strategies that aim to reduce vehicle speeds and improve safety for drivers, cyclists, and pedestrians. By creating a safer and more comfortable environment for those outside of motor vehicles, traffic calming may also increase pedestrian and bicycle activity.
Changing road designs: Traffic calming measures reduce vehicle speeds by either altering the configuration of the road or how drivers perceive and respond to it. Common examples of traffic calming measures include chicanes, speed humps, roundabouts, among others.
Led by local governments: Typically, traffic calming efforts are led by city or county Departments of Transportation or public works. In some communities, local governments have established traffic calming programs, where residents can petition for traffic calming measures to be added to their street. In other areas, traffic calming measures are incorporated into city or country policy (e.g., in a road design guide) and are installed as roads are redesigned.
Evidence and impacts
Ranked as having the highest level of evidence by County Health Rankings and Roadmaps
Multiple studies with rigorous designs demonstrate that traffic calming is a well-supported strategy for reducing traffic speeds.
- This assessment is based on evidence from a 2018 systematic review.
Best practices in implementation
Create a process for public participation: When considering the implementation of a traffic calming program, local governments should engage in a formal public engagement process. This may include convening an appointed advisory group, holding informational workshops, disseminating information online, among other approaches. Regardless of the approach, the process should allow for professional staff to explain the proposed traffic calming measures and for members of the public to communicate how they perceive the problem and proposed solutions.
Establish a process to identify potential projects: An effective traffic calming program should allow for both residents and city staff to identify roads segments that may benefit from traffic calming. If a request comes from an individual, local governments may require the individual to demonstrate broader support for traffic calming measures in the affected area (e.g., through a petition). Regardless of the source of the recommendation, professional staff should determine whether traffic calming would be effective in the proposed location.
Collect data on the problem: Before implementing traffic calming measures, local governments should collect data on how the roads in the affected area are functioning. These data can then be compared to those from after traffic calming is implemented to assess the intervention’s impact. Common data points to collect include average speed, 85th percentile speed, vehicle volume, crash data, and pedestrian and bicycle counts.
Consider the use of pilot projects: If traffic calming is a new or unfamiliar concept to residents, or if a local government expects that opposition to traffic calming measures may be high, a pilot installation may be appropriate. By using low-cost and easily-installed materials, local governments can “trial” traffic calming measures over a three to six month period. This approach allows the local government to collect data to demonstrate the installation’s impact and for community members to experience the changes first-hand.