Chicanes
A chicane (shi-kane) is a two or three section curb protuberance that forces motorists to maneuver through a narrow, single or two lane angled roadway section at a midblock location. Single lane chicanes restrict two-way traffic, requiring motorists to alternate traversing the narrow one lane roadway section. Two lane chicanes (also called "tadpoles") accommodate two directional flow simultaneously.
On single lane chicanes, if one does not encounter opposing traffic, the chicane forces one to drive slowly through the traffic calming device resulting in a point reduction in speed. Motorists encountering opposing traffic may have to yield for opposing vehicles to pass before proceeding. A "tadpole" chicane would function similarly to a mid-block traffic circle.
Chicanes introduce two traffic calming concepts: physical constraints and visual traffic calming. Level 3 traffic calming involves physical constraints which produces a point speed reduction. Point speed reductions may occur at a chicane, but motorist speed beyond the chicane are typically either unaffected or higher than before installation, unless used within a -system of traffic calming measures. Visual traffic calming involves installing features which provide visual breaks along long sections of roadway to make the roadway appear either shorter or as a not a through route.
Chicanes offer several benefits to the neighborhood. These include the following:
• Visual traffic calming effect and point speed reduction
• Opportunities for landscaping
• Minimal impact to emergency vehicle access.
Design considerations and negative impacts include the following:
• Possible increase in speeds beyond the chicane
• Increased noise at the chicane
• Removal of on-street parking
• May divert traffic to other adjacent roadways
• Increased potential for motorists hitting the curb
IMPLEMENTATION
Beneficial on long, straight, flat roadway sections where visual traffic calming effects apply. Design considerations should include street lighting, accommodating large vehicles (fire trucks, garbage trucks, moving vans, etc.), advance signing, maintaining adequate drainage, bicycle access, landscaping, and the associated maintenance and sight distance issues.