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Traffic Calming

Roadway Narrowing | Lateral / Horizontal Shifts | Raised Devices | Complementary Tools | Whole Street Designs

Traffic calming is a way to design streets, using engineering principles, to encourage people to drive more slowly. It creates physical and visual cues that induce drivers to travel at appropriate speeds. Traffic calming is self-enforcing. The design of the roadway results in the desired effect, without reliance on enforcement or voluntary compliance. Traffic control devices such as signals and signs rely on compliance. While elements such as landscaping and lighting do not force a change in driver behavior, they do provide the visual cues that encourage people to drive more slowly.

The reason traffic calming is such a powerful and compelling tool is that it has proven to be so effective. Some of the goals of traffic calming are clearly measurable such as increasing safety through fewer and less severe crashes. Others such as supporting community and livability - are less tangible but equally important.

Numerous studies throughout Europe, Australia and North America have shown that traffic calming reduces traffic speeds, the number and severity of crashes, and noise levels. In the Netherlands, an evaluation of 44 redesigned roads found a 72 percent reduction in the frequency of crashes. Extensive studies in Germany, France and Britain show speed and/or crash reductions of 30 percent-53 percent.7 In Vancouver, BC, an analysis of traffic calming in four neighborhoods quantified the substantial economic benefits arising from fewer crashes. These included reductions in police, fire, hospital, and insurance costs. Conversely, higher speeds have a negative effect: an increase in the average speed of motor vehicle traffic by 1 km/hour increases the number of injury crashes by approximately 3 percent and increases crash related costs by approximately 6 percent.

There are certain overall considerations that are applicable to both traffic management and traffic calming:

• In terms of safety, speed is more critical than volume and should be addressed first where there are monetary constraints.

• Neighborhood involvement is important to successful

• Traffic calming and management measures should fit into and preferably enhance, the street environment.

• Traffic calming and management measures should make sense.

• Traffic calming designs should be predictable rather than random, and easy to understand by drivers and other users.

• Devices that meet multiple goals are usually more acceptable. For example, a raised crosswalk is more understandable to motorists than a speed hump. The former has a clear goal whereas the latter may be perceived as a nuisance.

This midblock crossing is in Kalamazoo, Michigan. The landscaping and textured crosswalk are visually appealing and provide a clear message about where pedestrians can be expected to cross the street.

• Devices need to be well designed and be based on current available information on their applications and effects. Information of U.S. experiences with various traffic calming measures are found in ITE’s “Traffic Calming: State of the Practice.

• Traffic calming areas or devices should be adequately signed, marked and lit to be visible to motorists.

• Devices need to be spaced appropriately to have the desired effect on speed - too far apart and they will have limited effect, too close and they will be an unnecessary cost and annoyance. Devices usually need to be spaced about 300-500 feet apart. If they are spaced too far apart, motorists may speed up between them. This is particularly the case where the devices are added onto the street, e.g., speed humps. Whole street designs are usually able to create an environment that supports slower speeds for the entire length.

• Devices should not be under–designed, or they will not work. Keeping the slopes too gradual for a speed table or curves too gentle for a chicane will not solve the problem and will appear as a waste of money and may ruin chances for future projects.

• If a measure is likely to divert traffic, the area-wide street system should be considered so as not to shift the problem from one place to another.

Traffic calming tools may be used in combination, and are often most effective this way. The tools in this guide are organized into the following categories:

Some tools fall into multiple categories, but for simplicity are listed only once.

Trials and Temporary Installations for Traffic Calming

In communities trying traffic calming for the first time, it may be useful to lay out a new design with cones or temporary markings to test it. This provides emergency vehicle drivers, residents and others with an opportunity to test the design to assure that they are comfortable with it. Some communities have constructed elaborate temporary devices with concrete (“jersey”) barriers, or plastic barriers. These can instill a negative reaction in the community due to their unaesthetic nature. They do not generally have any significant benefits over the simpler test run devices, and it is better to go straight to a final product, which is more appropriate for a neighborhood setting.

The material provided on this page is from the FHWA publication "Pedestrian Facilities User Guide." This guide is currently under review by practicioners and others in the field. Subsequently, the material provided on this page is subject to change in the future.

Roadway Narrowing

Lateral / Horizontal Shifts

Raised Devices

Complementary Tools

Whole Street Designs

The Institute of Transportation Engineers has arrived at the following definition of traffic calming, which is often used in the United States:

Traffic calming is the combination of mainly physical measures that reduce the negative effects of motor vehicle use, alter driver behavior and improve conditions for non-motorized street users


The Federal Highway Administration inaugurated a new Web site dedicated to all the known and/or electronically publicized transportation programs and studies that pertain to traffic calming.
go to site

The site provides:

The general objectives of traffic calming
Traffic calming measures
Traffic calming measures
Links to traffic calming programs
Direct links to other related agencies
A list of recent studies
A list of any upcoming events
An intake page for reader feedback and contact information

Traffic calming improvements need to include input from and coordination with neighborhoods which are impacted

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