Left turn calming uses modular speed bumps, plastic curbing, flexible posts, and thermoplastic to slow turning speeds and improve left-turning drivers’ view of the crosswalk.
How left turn calming supports safety:
- Safer turning speeds
- Prevent corner cutting
- Turning vehicles more directly face crosswalks, improving drivers' view of pedestrians
Left turns present special hazards to vulnerable road users. One of the most common crash types on High Crash Network streets in Portland occurs when a person in a crosswalk is hit by a left-turning driver. Left-turning drivers can also collide with people biking straight through an intersection. Left turn calming may help prevent these crashes.
Portland is piloting left turn calming starting in summer 2019 and continuing into 2020. Evaluation results will inform long-term use. Preliminary results from New York City indicate that left turn calming may be an effective safety treatment.
Treatment location criteria
- 1-way to 2-way or 2-way to 2-way streets
- Appropriate geometry
- Any number of travel lanes
- Permissive lefts allowed (no left turn signal)
- Traffic signal
- Located on High Crash Network street, High Crash Network Intersection for people walking or biking, or history of left turn crashes
|Pilot treatment locations||Details||Status|
|E Burnside Street & 55th Avenue||Installed 6/18/2019|
|E Burnside Street & 60th Avenue||Pending installation|
|SE Stark Street & 99th Avenue||South leg only, wedge on NE corner||Installed 7/24/2019|
|SE Stark Street & 117th Avenue||Installed 10/4/2019|
|SE 122nd Avenue & Market Street||Installed 6/10/2019|
|SE 122nd Avenue & Harold Street||Installed 8/24/2019|
|SE César E. Chávez & Holgate boulevards||South leg only||Pending installation|
|SE Holgate Boulevard & 104th Avenue||Installed 7/25/2019|
|SE 106th Avenue & Washington Street||North leg only||Installed 7/24/2019|
|SE Stark Street & 139th Avenue||Installed 10/7/2019|
|SE Division Street & 174th Avenue||Installed 5/17/2019|
|SE Foster Road & 92nd Avenue||South leg only||Pending installation|
|SE Foster Road & 110th/111th avenues||Installed 5/16/2019|
|N Portsmouth Avenue & Willamette Boulevard||Preparing work order|
|N Killingsworth & Williams streets||West leg only||Pending installation|
|NE 122nd Avenue & Fremont Street||Preparing work order|
|NE 67th Avenue & Glisan Street||Preparing work order|
|NE Martin Luther King Jr. Boulevard & Lloyd boulevards||Wedge only, NE corner||Pending installation|
|NE Martin Luther King Jr. Boulevard & Ainsworth Street||Preparing work order|
|NE Martin Luther King Jr. Boulevard & Dekum Street||Preparing work order|
|NE Weidler Street & 16th Avenue||Preparing work order|
|SE 7th Avenue & Hawthorne Boulevard||Wedge only (posts), SW corner||Installed 4/27/2019|
|SE Hawthorne Boulevard & 30th Avenue||Installed 7/20/2019|
|SE Flavel Street & 52nd Avenue||Preparing work order|
|SW Market Street & 4th Avenue||Wedge only, SE corner||Installed 9/27/2019|
|SW Columbia Street & 4th Avenue||Wedge only, NW corner||Installed 9/26/2019|
|W Burnside Street & 3rd Avenue||East leg only, wedge on SW corner||Installed 9/15/2019|
|W Burnside Street & 11th Avenue||East leg only||Installed 9/15/2019|
|W Burnside Street & 21st Avenue||Installed 9/15/2019|
|NW Couch Street & 10th Avenue||West leg only||Installed 9/15/2019|
|SW 10th Avenue & Jefferson Street||Wedge only, SW corner||Preparing work order|
|SW Alder Street & 13th Avenue||Wedge only, SW corner||Installed 6/29/2019|
|SW Capitol Highway & Sunset Boulevard||Installed 9/15/2019|
|SW Beaverton-Hillsdale Highway & Shattuck Road||Installed 4/2019|
|SW Beaverton-Hillsdale Highway & Dosch Road||Preparing work order|
|N Interstate Avenue & Mississippi Street||Wedge only, SE corner||Installed 7/15/2019|
|SE 96th Avenue & Main Street||Preparing work order|
|SE Division Street / 20th Avenue / Ladd Avenue||Pending installation|
|SE Belmont Street & 30th Avenue||Installed 7/20/2019|
|SE Stark Street & 102nd Avenue||Wedge only, SE corner||Installed 6/18/2019|
Left turn calming includes a hardened centerline and/or a “wedge” at intersection corners. Wedges are similar to curb extensions, but are located outside of crosswalks and can be driven over if necessary.
Portland is testing two types of hardened centerlines: one using a combination of plastic curbing, posts, and rubber speed bumps, and another design that uses only rubber speed bumps. Where space allows, Portland installs an additional rubber speed bump "nose" that extends slightly into the intersection.
Most wedges use only rubber speed bumps and thermoplastic, and may be used to slow left- or right-turning drivers.
Hardened centerlines with noses can be seen below at East Burnside Street & 55th Avenue:
The pilot will be judged successful if any of the treatment variations result in:
- Slower turning speeds,
- Less corner cutting, and
- Reasonable maintenance costs
If the pilot is successful, PBOT will determine whether pilot treatment locations become program assets or maintenance assets and will consider expanding treatment locations.
Once crash data is available, PBOT will re-evaluate the treatment locations to inform long-term plans.
Questions about the pilot: Email Matt Kelly or call 503-823-5831