(Ed Note: Most of the information on Bicycle Friendly Street treatments in this post comes from the new Bike Plan’s Technical Design Handbook. Though we are happy to present it in bite-sized pieces, we highly recommend you download it yourself and have a good read. You can download the Technical Design Handbook here. For a refresher on Bicycle Friendly Streets generally–read our introductory post here.)
It’s time for yet another installment in our ongoing series that details the specific treatments that go into making a Bicycle Friendly Street (BFS). Today, we will examine chicanes – a traffic calming device. Traffic calming devices are considered “Level Four” BFS applications based on level of physical intensity. It is important to note that BFS applications are site-specific, and that not all streets require the highest application treatments. The Bike Plan Technical Design Handbook (TDH) recommends gathering community input along with the necessary engineering and design work to determine the level of application necessary for each individual street. In case you were wondering, there are five different application levels – varying from signage to traffic diversion.
Chicanes are alternating curb extensions that create an S shaped curve in the street. They are categorized as horizontal deflectors – as opposed to vertical deflectors like speed bumps. Chicanes are best utilized along narrow streets so that cars will be more inclined to slow down. Their primary purpose is to slow vehicular traffic, but they may also be used to beautify neighborhoods through improved landscaping. Chicanes can also enhance the pedestrian experience through expanded curbs areas.
- Chicanes discourage high vehicle speeds by creating an S shaped bend in the road
- They have minimal impact on emergency response vehicles compared to speed bumps, speed humps and other vertical deflection measures.
- Some on-street vehicular parking may need to be removed
- The narrowing of the road may force bicyclists to move into vehicular traffic flow
Here’s a nice visual provided by Streetfilms that details how chicanes work!
[vimeo http://www.vimeo.com/12796823 w=400&h=300]
Things to Consider
Chicane application costs can vary greatly depending upon the treatment’s intensity. Configuring on-street parking to create a chicane effect is the most inexpensive design solution, but it lacks neighborhood beautification features (landscaping, curb extensions, etc). It is important to note that upkeep is usually the responsibility of a neighborhood group – similar agreements are needed for round-a-bout’s with landscaping.
Chicanes with curb extensions and landscaping can be quite costly, especially if there are drainage issues. Drainage issues are very important as any treatment that impedes the flow of water may cause unnecessary flooding. Drainage issues must be mitigated during the design phase of any BFS facility.
We close with some lovely images of chicanes – enjoy!