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Traffic Calming


Traffic calming refers to a wide range of techniques used to improve safety, to reduce negative effects of motor vehicle in impacted neighborhoods and to encourage non-motorized street uses.

Almost every elected city or county official nationwide has fielded requests for lower speed limits, additional stop signs and 'children at play' signs to slow traffic. They have also almost certainly heard from other citizens completely frustrated by slow speeds, traffic congestion, and stop signs seemingly every block. Traffic calming objectives include slower speeds for motor vehicles, reducing collisions, reducing the need for police enforcement, improving the streetscape, and reducing cut-through motor vehicle traffic. A neighbourhood's perception of safety is as important as the reality. Experience and research have shown, however, that not all quick fixes requested by citizens are effective, and that systematic evaluation of these requests can reduce wasted expenditures and lead to better long-term solutions.

Several larger cities and counties have traffic calming programs in place, although some - like Kirkland and Bellingham - have largely eliminated their programs due to budget cuts. Bellevue's Residential Traffic Guidebook is a comprehensive resource on the subject, including both a number of traffic calming methods both structural and non-structural, an effective five-step plan for working with citizens to create, implement, and review Traffic Action Plans to ensure safety on the roads.

Links to Washington City and County Traffic Calming Webpages

Application of Calming Techniques

There are numerous techniques available for consideration when tackling the issue of traffic calming, including speed humps and cushions, chicanes, curb extensions, traffic circles, roundabouts, medians, signs, and speed limits. The optimal choice for a particular intersection or city depends on

Three of the frequently misapplied traffic calming techniques are lowering speed limits, placing stop signs, and, in residential neighbourhoods, placing "Children at Play" signs. Used properly, any of these techniques can be effective at traffic calming. Used improperly, however, and they may result in a reduction in overall traffic safety.

Speed Limits

Bellevue's Residential Traffic Guidebook specifically denotes lowering speed limits as an option they do not consider in creating an action plan for traffic calming:

Engineering studies show that speed limit signs are not the most significant factor influencing driver speeds. Research indicates that a reasonable and prudent driver will drive the speed suggested by roadway and traffic conditions, to the extent of disregarding the posted speed limit. A speed limit that is unrealistic invites the majority of drivers to disregard posted speeds. [...] Lowering the posted speed limit does not significantly lower traffic speed and can lead to unreasonable ticketing for acceptable driving behavior.

Stop Signs

Although frequently requested by citizens, evidence shows that placing additional stop signs in residential neighborhoods is not effective at speed control. Kirkland, WA's Traffic Calming Devices page sums up the issue in three points: Drivers will frequently ignore unneeded stop signs, leading to a sense of 'false security.' Stop signs are also largely ineffective at slowing speeds - drivers will slow within a block of the sign, but then speed up immediately after passing through. Stop signs can also lead to increased noise and pollution due to tire and engine noise, as well as increase automobile exhaust emissions and fuel consumption near the stop sign itself.

For more information, the city of Troy, MI, published a Stop Sign brochure as well as a detailed report on Multi-way Stops.

Children at Play Signs

Like all signs, children at play signs are meant to inform and direct motorists - in this case, that children may be playing in the neighbourhood. However, unnecessary signs can have the unintentional effect of causing motorists to ignore or disrespect all signs - causing more harm than good despite the best of intentions.

The city of Greenville, SC has produced a number of "Traffic FAQs" on many topics, including Will "Children at Play" signs help slow traffic? which states, in part:

While it may seem that this sign would protect neighborhood youngsters, facts indicate otherwise. Although some communities have posted these signs in residential areas, no evidence exists to prove that these signs help reduce pedestrian accidents or lower speeds. Studies have shown that many signs in residential areas, which are installed to "warn" people of normal conditions, fail to improve safety. Pedestrians can get a false sense of security since drivers often disregard these signs. Signs that encourage parents or children to believe they have added protection (which they do not) can do more harm than good. Children should not be encouraged to play in the street. Federal standards reject these signs because they openly suggest that playing in the street is acceptable.

Traffic Calming Information Resources

For more information on how governments nationwide are dealing with the issue of traffic calming, see these resources.

Last Modified: January 08, 2016