District 1 Seattle City Councilmember Lisa Herbold shared an update on the repair and maintenance schedule now in place regarding the West Seattle Bridge.

At the West Seattle Bridge Community Task Force, Kraemer North American, the contractor for the West Seattle Bridge repair, presented schedule details for the repair and major maintenance, and detailed drawings showing where work will take place.

First, a note that SDOT will be updating, on an ongoing basis, the visual below as one way to illustrate the progress on repair work listing status of work by color coding.

This locations shown in orange as “under construction” are where hydro blasting is occurring to be able to mount external work platforms, which will be moved along the west and east bridge spans for carbon fiber wrapping and epoxy injections on the outside of the bridge. Work platforms are shown in blue as “coming soon.” Once the hydroblasting is complete, for example, the orange area will then be shown in green as “complete.”

Repair Overview

Below is information about the repair presented by Kraemer North America.

This slide shows where repairs will take place. In case it’s not visible on your device, here’s a link to a larger visual for this and the next slide. In the drawings, “PT” means steel post-tensioning (shown in the green line), and “CFRP strengthening” means carbon fiber polymer wrap strengthening (shown in blue for exterior work, and purple for additions inside the bridge).

Plans for the lower bridge are in the bottom drawing.

Below is a visual of the bridge deck from above (the second slide linked here). Some of the work shown here is for major maintenance, as described below.

The green lines are expansion joints that will be replaced; the blue lines are expansion joints that will be rehabilitated.

The area in red is where a new bridge deck overlay will be added on the Fauntleroy Expressway.

10 overheard sign structures will be added, replacing existing signs. In addition, new jersey barriers will be installed, 4000+ feet long.

West Seattle Bridge Repair Schedule

Here’s the first detailed schedule for repairs to the West Seattle Bridge, working toward mid-2022 completion. It shows the timetable for repair elements including carbon fiber polymer work from December 2021 to May 2022, post tensioning during March and April 2022, crack injection from December 2021 to May 2022 and restoration of the bridge deck in June 2022:

Bridge Major Maintenance

In addition to the repair work, SDOT is performing major maintenance to the bridge during this time period. This will reduce the need for future lane closures. The work is possible because additional geotechnical review determined that seismic stabilization of Pier 18 will not be needed at this time, as originally forecasted.

Funds originally planned for use on Pier 18 stabilization are now directed to major maintenance, including work on expansion joints shown in the bridge deck map above, concrete overlay and carbon fiber wraps. If SDOT hadn’t reallocated federal grant funds to this work, they’d have to be returned to the federal government.

Work also includes re-striping the roadway and replacing signs. Kraemer noted if the signs cannot be installed before the bridge re-opens, they will be installed overnight to minimize impact on traffic.

Carbon Fiber Reinforcing Polymer Wrap

Carbon fiber wrap will be used outside and inside the bridge. It is as strong as steel. Epoxy injections will be used to seal cracks in the concrete; after that, concrete will be polished, and then the carbon fiber will be installed to prevent cracks. Paint with UV protection will then be added to avoid degradation of carbon fiber.

Post-tensioning

The slide below includes detail from Kraemer about the steel post-tensioning work. It notes the post-tensioning steel strands will be 46.75 miles if stretched end to end, and include 20.8 million pounds of force, compared to 6.72 million pounds of force in the emergency stabilization work done last year.

The post-tensioning steel strands will be added across the entire structure. The purpose is to pull the bridge from end to end tighter together, to get the concrete to press into itself (concrete isn’t inherently strong in tension). Some post-tensioning was included in the original bridge, but more is needed.

A key element of post-tensioning is ensuring that it works to maintain the geometry of the bridge, with the center higher, and Piers 15 and 18 lower. This is one reason why design is important to success of the project; another is the addition of 92 tons of steel and 24 tons of concreate. The additional weight must be accurately balanced.

Bridge Access: Work platforms

Work platforms will be used in two sections starting by Pier 15 and Pier 18, as shown above. They will be movable along the east and west portions of the work area, to add epoxy and carbon fiber wrap.

They were designed for the bridge during stabilization. Winching systems are on site, and the hydroblasting will allow the platforms to be hoisted into place.

Here is a link to additional details and visuals on High Bridge Access

To limit interruption to marine traffic and traffic on the lower bridge, the platform raising will be scheduled for an evening or weekend.  Once work is complete, platforms will be returned to the ends at Piers 15 and 18 and lowered.

The “hydroblasting” work consists of water pressurized at 8,000 pounds per square inch. This is sufficient to remove the concrete, but doesn’t damage tensioning strands in the bridge, or the rebar in the structure.

You may have seen firefighters on the bridge deck this week; they were there for training exercises.

Reconnect West Seattle Updates

The Duwamish Longhouse interim signal on West Marginal is now operational. A permanent signal will be installed later. This has been a longstanding request of the Duwamish, dating to the opening of the Longhouse in 2009, to enhance access.

Below are updates SDOT provided regarding Reconnect West Seattle Projects.

Traffic mitigation:

• SDOT completed some tree maintenance work on West Marginal Way SW, north of the Highland Park Way SW intersection. 
• On 9th Ave SW & SW Portland St and 16th Ave SW & SW Holly St, SDOT constructed speed cushions to mitigate high motorists' travel speeds. Our transportation operations division is still working with the Seattle Fire Department to resume traffic calming discussions in a few locations in West Seattle. SDOT has paused speed hump/cushion installation in 2021 to allow for these discussions. 
• SDOT built new curb ramps on SW 28th St and SW Thistle St. 
• SDOT installed eight “paint and post” projects – in the Fauntleroy neighborhood (6 at the locations below) and at Marginal Way Pl SW and 17th Ave SW (2): 
  • 45th Ave SW and Wildwood Pl SW 
  • California Ave SW (at Fauntleroy Church and YMCA) 
  • 37th Ave SW and SW Thistle St

Home Zones

South Park:

• SDOT is working with abutting property owners in the development of conveyance swale and walkway projects, since those property owners will need to care for the improvements.

 Highland Park:

• SDOT is still engaged with concerned property owners on 14th Ave SW between SW Kenyon St and SW Elmgrove St about tree planting impacts on parking and potential future view loss. SDOT will attempt one more design modification with the community to determine if a low-cost walkway could move forward for this street. 
• SDOT is meeting with the Parks Department about a recommended walkway along the north side of SW Webster St (south side of Riverview Park) and discuss the design that is within their property and determine if this project will move forward. The community desires a walkway. 
• The SDOT Urban Forestry crews are currently planting approximately 50 trees in the Highland Park Home Zone on SW Barton St, which will become a Neighborhood Greenway in early 2022. The crews will be alternating with Oak, Elm, Ironwood and Dogwood. 
• The Home Zone communities are excited for the trees as they combat air pollution from the increased traffic and corresponding emissions they have experienced due to West Seattle reroutes.