Chicanes create a horizontal diversion of traffic and can be gentler or more restrictive depending on the design.
Diverting the Path of Travel
Shifting a travel lane has an effect on speeds as long as the taper is not so gradual that motorists can maintain speeds. For traffic calming, the taper lengths may be as much as half of what is suggested in traditional highway engineering. The taper lengths should reflect the desired speed which should be posted prior to the chicane.
Shifts in travelways can be created by shifting parking from one side to the other (if there is only space for one side of parking) or by building landscaped islands (islands can also effectively supplement the parking shift).
Diversion Plus Lane Restriction (Angled Slow Points)
Diverting the path of travel plus restricting the lanes (as described in the section on chokers) usually consists of a series of curb extensions, narrowing the street to two narrow lanes or one lane at selected points and forcing motorists to slow down to maneuver between them. Such treatments are intended for use only on residential streets with low traffic volumes.
If there is no restriction (i.e., the number of lanes is maintained), chicanes can be created on streets with higher volumes, such as collectors or minor arterials.
Chicanes help reduce vehicle speeds and offer the opportunity to add more greenspace (landscaping) to a street.
- Chicanes may reduce on-street parking.
- Maintain good visibility by planting only low shrubs or trees with high canopies.
- Ensure that bicyclist safety and mobility are not diminished.
The cost of installing a landscaped chicane can range from approximately $2,000 to $26,000, depending on landscaping, drainage requirements and the need for utility relocation. More detailed cost information can be found here.