Traffic Calming

Strategies > Transportation Infrastructure > Traffic Calming

Traffic Calming

Photo: Flickr/ Richard Drdul

Traffic calming refers to streetscape design features intended to reduce vehicle traffic speeds and typically used to improve safety for pedestrians and bicyclists. Traffic calming can be considered an engineering countermeasure to improve safety. Traffic calming features may reduce speeds through vertical deflection (e.g., speed hump), horizontal deflection (e.g., chicane, pictured), or road narrowing (e.g. curb extensions). Sometimes traffic diverters are included as a traffic calming strategy, although they reduce traffic volumes, not speeds.

Traffic calming can be implemented in problem spots or as part of area traffic management. Studies suggest that area-wide implementation may be more effective (Bellefleur & Gagnon, 2011).

Proven Outcomes

Increased Physical Activity

Increased Walking

Reduced Vehicle Speeds

Improved Perception of Safety

Traffic calming is a recommended strategy for increasing walking and physical activity (Community Guide, 2016) and a scientifically supported strategy for reducing vehicle speeds and increasing perceptions of safety (Cairns et al., 2015; County Health Rankings & Roadmaps, 2018).

Likely Outcomes

Increased Cycling

Reduced Crashes

Improved Aesthetics

Potential benefits include increased walking and cycling and reduced crashes. Streetscape improvements associated with traffic calming may improve aesthetics and generate positive perceptions of the space (Cairns et al., 2015; Community Guide, 2016; County Health Rankings & Roadmaps, 2018).

Traffic calming could increase or decrease air pollutant emissions. This depends in part on the type of pollutant and type of traffic calming intervention--traffic circles can reduce emissions but speed humps and stop signs are more likely to increase emissions. Introducing landscaping as part of traffic calming may help absorb pollution but requires further study (Bellefleur & Gagnon, 2011).

Equity and Inclusion

From a safety perspective, traffic calming appears to especially benefit older adults and children. A "black spot" approach to traffic calming, where only one site is treated with an intervention, could divert traffic onto other streets. Generally, consider the demographics of the population that is benefiting from traffic calming and who might be burdened with any possible diversions. Ensure that improvements are accessible to people with disabilities. Contact your local Center for Independent Living for help assessing the accessibility of plans and projects.

Strategies that involve changes to the physical environment, such as traffic calming, may increase the attractiveness of an area. An increased demand for housing may result in increased property values or rents and could lead to involuntary displacement if appropriate mitigation strategies are not put into place. The lessons learned from anti-displacement efforts in several cities can be found in this PolicyLink report. Practitioners can evaluate the risk of displacement through the methods described by Chapple et al. (2017) or Bates (2013)