Traffic calming

Traffic calming reduces vehicle speeds by using roadway design elements, like roundabouts, narrowed roads and speed humps. Traffic calming supports the livability and vitality of residential and commercial areas by improving the safety, mobility, and comfort for all road users, with special care taken for pedestrians and bicyclists.

Key characteristics




WSDOT regions

Other names

  • Livable streets
  • Livability

Strategy description

Traffic calming alters the road layout and appearance to make streets safer for drivers, pedestrians and bicyclists. By increasing the safety and efficiency of all users, traffic calming transforms streets and helps create a sense of place for communities. 

A primary technique in traffic calming is the use of physical roadway design elements to reduce vehicle speeds.

Here are some examples:

  • Forcing vehicle movement, sometimes unexpected, that encourages motorists to slow down.
    • Side-to-side movement techniques include shifting lanes, realigning intersections, and installing roundabouts.
    • Up-and-down movement techniques include in-roadway items like speed humps and raised crosswalks.
  • Reducing the street width and narrowing lanes through the use of striping, median islands, plantings, pavement marking, on-street parking, and corner extensions for pedestrians (sometimes called a “bulb out”).
  • Routing restrictions like full closures to motor vehicles, half closures, and median barriers.

When to use this strategy

Traffic calming makes sense for areas where there are potential conflicts between motor vehicles and pedestrians or bicyclists.

To determine if traffic calming is viable, agencies should evaluate the area and use traffic calming to minimize the negative effects on motor vehicle travel. These treatments are often built into an existing roadway to blend into its surroundings. Effective use of traffic calming involves finding a balance between the need to provide an efficient transportation network and to maintain a livable and safe environment for those in the community, especially people who walk and bike.

Strategy benefits

Safety is a significant benefit as vehicle speed has a dramatic effect on the level of pedestrian injury when collisions occur. For example, the average risk of death for a pedestrian hit by a 23 mph vehicle is only 10 percent, but increases to 50 percent when that vehicle is traveling at 42 mph and 90% at 58 mph (1).

Additional benefits:

  • Reduced vehicle speeds that create safer conditions for pedestrians and bicyclists
  • Improved comfort for people who live, work, and play along the roadway
  • Encourages people to enjoy where they are, and to enjoy the journey, rather than just “get through it” to their destination
  • Increased commercial success because people can more easily visit businesses and spend more time in the area

What you need in order to implement

Policy needs:

  • Land use policies should be in place to encourage a calm traffic environment
  • Policies related to safety analysis and treatment implementation, pedestrian and bicycle considerations, and speed management that provide the backing for agencies to implement traffic calming solutions

Planning needs:

  • Land use planning should be in place to encourage traffic calming solutions
  • It is important that agencies maintain a clear process for the planning, evaluation, and implementation of traffic calming, both in residential neighborhoods and commercial business districts

Coordination needs:

  • Coordinate among traffic engineers, safety professionals, pedestrian and bicycle advocates, and adjacent property owners (residential and business)
  • Coordinate with other agencies that use special vehicles like fire trucks and buses to ensure the traffic calming additions accommodate emergency response without causing undue delay for these services
  • Coordinate with parking officials to determine the most appropriate number and type (e.g., angled, parallel, back-in) of parking spaces

Equipment needs:

  • Basic traffic engineering tools: signing, striping, and equipment to construct corner extensions or speed humps

Maintenance needs:

  • Regular maintenance of signing and striping, including sign inspections and replacement as needed. Some items, like plastic delineators, tend to get damaged more quickly than standard signs, so agencies should check these more often and replace them when they are no longer useful.
  • In areas where snowfall is expected, traffic calming should be designed to minimize impacts to snow removal operations

Agency resources needs:

  • Funding for treatments and experts to analyze where traffic calming enhancements will be the most successful

Learn more about this strategy

Federal Highway Administration (FHWA), Traffic Calming ePrimer.

Institute of Transportation Engineers (ITE) Traffic Calming Measures.

National Association of City Transportation Officials (NACTO), Speed Management website.

Works cited:

(1) Tefft, B.C. (2011). Impact Speed and a Pedestrian’s Risk of Severe Injury or Death. AAA Foundation for Traffic Safety (PDF).

About key characteristics

Location notes:

Traffic calming can be installed anywhere. It is most often used in urban and suburban settings in both residential communities and central business districts.

Cost notes:

Traffic calming implementation typically consists of low-cost signing, pavement marking, and plastic delineators.

Technology notes:

Minimal technology is needed for traffic calming treatments.

Collaboration notes:

Since traffic calming treatments change the layout of the roadway (e.g., reduce lane widths, extending curbs), it is important to collaborate among designers, traffic engineers, safety advocates, and emergency services personnel to ensure both mobility and safety needs are met.