Device name(s): Chicanes/Deviations
Approximate Cost:$30,000-$40,000 ($7,000$15,000 per pair)
Speed Reduction: 3-6 mph
Definition: Chicanes narrow the roadway with alternating curb extensions to create an S-shaped curve. Chicanes alter the road alignment and narrow the width of the travel lane in order to reduce motorists’ speed as they travel through the road segment. A chicane is a two-lane angled slow point created by staggered, triangular curb extensions that alter the traffic movement on a street from straight through to curving, slowing travel speeds. Data on chicanes’ effectiveness in reducing speed and collision is limited. Experience in the city of Seattle has found chianes to be effective in reducing speed from 18 to 35% overall.
Fast Facts:
- Can be used on Local Street- Yes
- Can be used on Collector- Yes
- Can be used on Arterial- No
- Reduces Speed-Yes
- Reduces Volume- No
- Noise Impact- No
- Restricts Access- No
- Bicyclist Impact- Possible
- Transit Impact- Yes
- Parking Impact- Yes
- Emergency Response Impact- No
Advantages:
- Effective in reducing speeds
- Most effective when used in a series
- Regulates parking with curb extensions
- Increases pedestrian safety by reducing vehicle speed
- Provides areas for landscaping
- Aesthetically pleasing
- Reduces vehicle speed without impaction emergency response
- discourage high speed by forcing a change in path or direction
- easily negotiable by large vehicles such as fire trucks)
Disadvantages:
- Increases regular maintenance
- Loss of parking
- Reduces on-street parking
- Reduces the space for motor vehicles to safely pass
- Requires wide right of way, or pavement width
- Expensive to install
- Creates significant changes to property frontage
- Requires maintenance of landscaping
- must be designed carefully to discourage drivers from diverting out of the appropriately named
- curb realignment and landscaping can be costly, especially if there are drainage issues
Criteria/Application(s):
- location where speeds are a problem but noise associated with the speed humps and related measures would be unacceptable
- 85th percentile is 5 mpg above speed limit or greater
- 60% of households in affected area must support
