Hardened Centerlines

Background

As part of our Vision Zero goal of ending traffic deaths and serious injuries by 2030, we will be installing new “hardened centerlines” at several intersections along Rainier Ave S.

What's a hardened centerline?

Hardened centerlines are small rubber barriers next to crosswalks that require people driving to make slower, squarer left-hand turns. This small change has been proven to significantly slow down vehicle speeds at crosswalks and improve safety for people in the crosswalk.

A before and after drawing representing a four-way intersection with crosswalks and a car turning left. The before image shows a driver making an angled turn through the middle of the intersection without the hardened centerline intervention. The after image shows the driver making a right angle turn to avoid the hardened centerline intervention.

Success in Other Cities and Seattle

Reports and data from other cities including Portland, New York City, and Washington, D.C. show that hardened centerlines reduce conflicts between people walking and people driving which, in turn, lowers the number of injuries and fatalities.

In Washington, D.C., hardened centerline installations were associated with a 70.5% reduction in conflicts between left-turning vehicles and pedestrians and a 67.1% reduction in the odds of a left-turning vehicle exceeding 15 mph. In Seattle, we installed a hardened centerline at the intersection of Denny Way and Stewart St in 2020. Observations indicate it has improved turn compliance.

Marco Conner DiAquoi, the Co-Deputy Director of New York City’s nonprofit Transportation Alternatives remarked that, “leading pedestrian intervals and hardened centerlines - seem to have had an enormous effect on pedestrian safety in particular. ‘From 2016 to ’17, we saw the biggest drop in pedestrian fatalities that I’ve ever seen.” (Schmitt, Right of Way 2020).

Where will these be?

When we were determining the locations for hardened centerlines, we took many things into consideration, including the following:

a history of pedestrian injuries and fatalities
intersections with traffic signals that do not have dedicated left turn phases (i.e. drivers have a green light at the same time that pedestrian have the crossing signal)
intersections within ¼ mile of a school or transit hub
areas where residents have lower incomes and rely heavily on transit

Based on these criteria, we selected 4 intersections along Rainier Ave S for Phase 1 (blue) construction in 2021/2022 and, in Phase 2 (orange), we plan to install hardened centerlines at additional intersections:

Map of south Seattle, including Rainier Avenue S, with 4 intersections along Rainier Ave S designated for Phase 1 Construction and 10 intersections designated for Phase 2 construction. Selected intersections run north from S Massachusetts St down to S Othello St.

Phase I

Rainier Ave S & S Massachusetts St
Rainier Ave S & S Andover St
S Ferdinand St & Rainier Ave S
Rainier Ave S & S Graham St

Phase II

Rainier Ave S & S Bayview St
Rainier Ave S & S Walden St
Rainier Ave S & Genesee St
S Charlestown & Rainier Ave S
Rainier Ave S & S Alaska St
Rainier Ave S & S Hudson St
Rainier Ave S & S Edmunds St
Rainier Ave S & S Orcas St
Rainier Ave S & S Holly St
Rainier Ave S & S Othello St

What’s Next?

We will begin installing hardened centerlines on September 12, 2021 and plan to complete installation at all locations along Rainier Ave S as early as spring 2022.

We’re excited to add hardened centerlines to our existing toolkit of infrastructure interventions that promote pedestrian and driver safety and awareness. So, whether you are walking, rolling, biking, or driving, be on the lookout for our new hardened centerlines along Rainier Ave S!