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 calming, the taper lengths may be as much as half what is suggested in traditional highway engineering.

Shifts in travel-ways 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 restriction (Angled Slow Points). Diverting the path of travel plus restricting the lanes (as described under "Chokers") usually consists of a series of bulb-outs or 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.

Purpose:

• Reduces vehicle speeds
• Adds more green to a street

Considerations:

• Chicane may reduce on-street parking.
• Maintain good visibility by planting only low shrubs or trees that with high canopies.

Estimated cost

Costs for landscaped chicanes are approximately $10,000 (for a set of 3 chicanes) on an asphalt street and $16,000 on a concrete street. Drainage may represent the most significant cost consideration.