Policy Factsheet

Area-wide traffic calming for preventing traffic related injuries

Reasons for Policy

  • In the U.S., pedestrian deaths account for 15% of all road traffic fatalities.1
  • In 2008, 4,378 pedestrians were killed and 69,000 pedestrian were injured in traffic crashes in the U.S.2
  • In 2008, nearly one in five children between the ages of 5 and 9 killed in traffic crashes were pedestrians.2
  • Area-wide traffic calming has the potential to reduce deaths and injuries.1

Community Groups

  • Local Government
  • Local Transportation Departments
  • State Government

Policy Components

  • Area-wide traffic calming measures designed to discourage the use of residential streets for through travel and create an environment where residential streets are safe. Strategies include:
  • Vertical and horizontal shifts in traffic (road humps, speed cushions, raised crosswalks, road narrowing)
  • Optical measures (chevron road signs, reflective surface treatment, shortened sightlines, alterations to road lighting)
  • Redistribution or alteration of traffic (permanent or temporary blocking of road, diagonal blocks, traffic circles, creation of one-way streets
  • Changes to road environment (increased vegetation along road)
  • Reduced speed limit zones

Desired Outcomes

  • Reduction in road traffic fatalities
  • Reduction in road traffic injuries
  • Reduction in traffic crashes
  • Reduction in pedestrian-motor vehicle collisions

Level of Evidence Available to Evaluate Effectiveness of Policy

For all policies we describe on this website, we have applied the Standards of Evidence as defined by Flay et al. (2005) in the Standards of Evidence document published by Prevention Science.

The effectiveness level of this policy is 2: Policies with Consistent Evidence from High-Quality Observational Studies.

The levels of effectiveness as noted are:

  1. meets criteria for policy effectiveness (consistent, positive outcomes from at least two high-quality experimental or quasi-experimental trials using a comparison group or interrupted time series design);
  2. consistent evidence available linking policy with positive outcomes from high-quality observational studies only;
  3. insufficient evidence available for policy or policy components.

Achievable Results

The following summary of achievable results is based on a published review of the scientific evidence.

On average, area-wide traffic calming can achieve:

  • Small reductions in road traffic injuries (RR = 0.85, 95% CI: 0.75-0.96)1

Note: Area-wide traffic calming appears to be a promising intervention for reducing traffic injuries and deaths (effects are in the hypothesized direction but not statistically significant). However, no studies with randomized controlled trials were found. Further research, which includes well-designed controlled studies, is needed to effectively evaluate traffic calming interventions.1

Community Examples

City of Lancaster, California, Public Works, Traffic Engineering Division implements a traffic calming policy.

City of Loveland, Colorado, Public Works implements a traffic calming program.

Links to Policy Examples

City of Lancaster Citywide Traffic Calming Policy

Loveland Municipal Code, Chapter 2.48 Department of Community Services

Be sure to check with your state, county, and municipal governments regarding potential existing laws that may impede any new policy development.

Local governments and organizations may check existing state and federal statutes and administrative codes for the authority to implement local policies.


1 Bunn, F, et al. (2003). Area-wide traffic calming for preventing traffic related injuries. Cochrane Database of Systematic Reviews 2003, 1, CD003110.

2 National Center for Statistics and Analysis, NHTSA (2009). Traffic Safety Facts: 2008 Data. National Highway and Traffic Safety Administration, Department of Transportation, Washington DC, DOT HS 811 163, retrieved from: <a href=http://www-nrd.nhtsa.dot.gov/Pubs/811163.PDF>Traffic Safety Facts 2008</a>

3 Flay, BR, Biglan, A, Boruch, RF, Ganzalez Castro, F, Gottfredson, D, Kellam, S, Moscicki, EK, Schinke, S, Valentine, JC, & Ji, P (2005). Standards of evidence: Criteria for efficacy, effectiveness and dissemination. Prevention Science, 6(3), 151-175.