Chokers and Chicanes
A choker has been installed on this street to calm traffic.
Traffic calming can also result from narrowing the street through the use of chokers and chicanes. Chokers narrow both sides of the street to form a section of about 20 to 24 feet wide. Chicanes provide alternating narrow and wide sections, and a curved driving path similar to a slalom. Chicanes work best when supplemented with centerline striping and in some cases edgeline striping. Both chokers and chicanes need to have a vertical element in the narrowed section such as landscaping so the narrowed section can be seen easily by approaching motorists. Lighting at the narrowed section is also helpful. If drivers do not see and perceive the narrowing treatments, they may not slow down, and may even collide with the narrowed street section. Care must be used to accommodate storm water runoff when designing chokers and chicanes, and they should not be used if it will result in the loss of bicycle lanes.
Treatment: Chokers and Chicanes
Parallel or offsetting curb extensions, which effectively reduce road width for a specific distance, that are intended to reduce motor vehicle speeds and cut-through traffic, and make drivers aware of pedestrian activity.
Few formal evaluations have been performed, but these treatments are implemented based on the assumption that they do in fact benefit pedestrians by slowing motor vehicle traffic, reducing the number of severe crashes and increasing safety.
Costs for chokers range from $5,000 to $20,000, depending on site conditions and landscaping [PEDSAFE, 2004] Costs for landscaped chicanes range from $10,000 (for a set of three chicanes) on an asphalt street to up to $30,000 on a concrete street [PEDSAFE, 2004]. Drainage and utility relocation often represent a significant portion of the cost for both chokers and chicanes.
Keys to Success
- For chokers to perform effectively, the street must be narrowed such that motor vehicles approaching from opposite directions will slow to pass or stop to allow the other driver to pass.
Key Factors to Consider
- Ensure that bicycle safety and mobility is not compromised and that streets are still wide enough to accommodate emergency motor vehicles.
- Chicanes may reduce the number of on-street parking spaces.
- Motor vehicle speeds.