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Chicane
A chicane is an S-shaped curve in the vehicle driving path. It can also be called a deviation, serpentine, reversing curve, or twist. Chicanes are
traffic calming
measures used to slow cars, usually on
residential streets. Most traffic calming chicanes are created by building
curb extensions
that alternate from one side of the street to the other [1a].
Design
Chicanes usually consist of at least three curb extensions in a row. They are used in the middle of a block or at a T intersection, and work best when there is equivalent traffic volume in each direction [2]. European traffic calming manuals recommend that curb extensions have a displacement of at least one lane and have an angle of deflection of at least 45 degrees. One issue with chicanes is that drivers can pass straight through them and maintain speed by crossing the middle line. This problem can be resolved by the construction of a center island [1a].
Advantages
When properly designed and installed, chicanes can be effective at reducing motorist speed. They can also beautify and improve the street for pedestrians, with expanded curb areas and landscaping. Unlike some calming measures, such as street closures, chicanes do not block access to the street [2].
Disadvantages
Chicanes may require manual street cleaning, due to their irregular shape [2]. Given the complexity of curb extensions and the landscaping costs, chicanes are costlier to create than many other traffic-calming measures. For this reason, they are not as commonly seen as other measures, such as traffic circles [1a].
Emergency Response 
Fire-rescue teams generally prefer chicanes and other horizontal traffic calming measures to vertical measures, like
speed humps
. Though chicanes can slow down emergency vehicles slightly, they are better than the jostling that results from vertical measures. One solution to reduced response times is the creation of specific emergency vehicle routes, and placing chicanes only on non-emergency route streets [1b].
Modified Chicanes
One solution to the cost issue of chicanes is to utilize parking areas. Alternating on-street parking areas from one side of the street to the other creates a chicane-like effect at minimal cost. These parking areas can be parallel or angled, and they can be created simply by painting new markings on the pavement. For a more aesthetic approach, partial curb extensions and landscaping may be used to screen the parking areas and beautify the area. Many Main Street revitalization projects have used this approach, and improved the overall street environment as well as slowed the speeds of passing motorists [1a].
ALSO ON THE LIVABLE STREETS NETWORK
REFERENCES
Each source is referred to by the same number every time it is cited. Please keep citation style consistent.
[1] Ewing, Ried. Traffic Calming: State of the Practice. Institute of Transportation Engineers (ITE)/Federal Highway Administration (FHWA). August 1999.
[1a] Ibid., pp. 39-40.
[1b] Ibid, pp. 147-149.
[2] Institute of Transportation Engineers. 14 Apr. 2008.
PICTURE REFERENCES
Pictures are cited in the order they appear above. Please keep citation style consistent.
[1] One-lane chicane. Photo by Richard Drdul via Flickr.
[2] Bi-directional chicane at T intersection, Oceanside, California. Photo by Andy Hamilton.
FURTHER READING
