Short term repair plans detailed in third West Seattle Bridge meeting; Carbon fiber wraps on girders and more steel will strengthen damaged span
Carbon fiber-reinforced polymer wrap, more post-tensioned steel and more epoxy comprise the focus of the emergency repair and stabilization of the ailing West Seatttle Bridge. This, according to the Seattle Department of Transportation (SDOT) in the third of a series on onging meetings on the transportation crisis affecting West Seattle since March 23.
The City also extended its response deadline for its Request for Qualifications submissions for replacement of the bridge to July 9.
The low/swing bridge is now open to all traffic after 9pm SDOT said after getting unanimous agreement from the Community Task Force.
The online meeting featured an update from Matt Donahue, Roadway Structures Manager for SDOT. He outlined how the process will work.
After structural testing and the analysis of those tests is complete at some point this summer the decision to repair or replace will be made. Donahue acknowledged in last week’s meeting that the bridge can be repaired but it boils down to a cost/benefit ratio.
In either case contractor Kraemer North America is doing the work to stabilize and strengthen areas weakened by cracks and to make the bearing at Pier 18 functional. The shoring and design work (regardless of a replacement or the full repair) will go ahead following the decision point.
The Design of the long-term repair would be accomplished by the existing engineers working on the stabilization and would include:
• Carbon fiber-reinforced polymer (CFRP) wrap on affected girders
• Girder interior floor post-tensioning system
• Epoxy injection into cracks over .3mm in width prior to CFRP installation
To accomplish this:
• Temporary access platforms will be assembled on a barge adjacent to a channel under the bridge
• Crane barge will enter the channel in four-hour windows; four times to hoist platforms in July and four times to remove them in November
•When not in use, the barge will be moored on the east side, under the bridge footprint but outside the navigation channel
They will use four platforms total which will reduce channel clearances will be reduced by up to 7 feet. The platforms will be in place from July through November and amber lights will alert ships passing through of their presence. The barge from which the lifting/work platforms will be hoisted will be guided by two tugboats.
The process would use water cutting tools to create holes in the bridge deck through which cabling could be passed to attach to the platforms.
Donahue said that whether they repair or replace the bridge, seismic standard will be "high in mind."
During the work Kraemer will communicate with the lower bridge operators and the U.S. Coast Guard a week before to the start of each period of activity.
SDOT said they will try to contain any debris.
This fall is the earliest they will reach the go or no go status on repair or replace. "If we went the repair route the work would be an extension of of these efforts," said Donahue.
The meeting also served to introduce the Technical Advisory Panel (TAP)
Barbara Moffat, Co-Chair for TAP is a Vice President and Project Director with Stantec an international professional engineering services company in the design and consulting industry. Scott Phelan is the National Chief Bridge Engineer for David Evans and Associates of Seattle and with over 27 years of structural bridge engineering experience. He has worked on the final design of two of the largest, world record, concrete segmental bridges. Also part of the meeting was Adolph Furtado who is President of Lin & Associates. Furtado has more than 24 years of construction experience focusing on public infrastructure.
Confirmed TAP participants include:
- Stephen Dickenson, PhD, PE, DPE, New Albion Geotechnical, Inc.
- Gregg A Freeby, PE, American Segmental Bridge Institute (ASBI)
- Reggie Holt, PE, Federal Highway Administration (FHWA), Office of Bridges and Structures FHWA Headquarters, Washington DC
- Debbie D Lehmann, PE, Federal Highway Administration (FHWA) Washington Division Office
- Barbara Moffat, PE, SE, Stantec
- Scott Phelan, PhD, PE, SE, David Evans and Associates, Inc
- Professor John F Stanton, University of Washington
Moffat said that the members of the Technical Advisory Panel have met independently to discuss how they would work together and said she and Scott Phelan TAP co-chairs will work with the Community Task Force “looking for the best thing for the City of Seattle”
She said it was critical to understand why things are being done as they go forward meaning the TAP would spend some time looking at culpability in the bridge failure, something Councilmember Lisa Herbold said she appreciated.
Moffat said for now the TAP members "are focused on data gathering and emergency repairs." She said that they have not seen any proof thus far that would preclude a more complete repair but also that "We haven't seen anything that proves a repair should be done," speaking regarding once a final repair or replace decision has been made.
They do have a breadth of experience Moffat said. She was involved in an immersed tube tunnel project in Boston. "I have the expertise and first hand knowledge of how that works," and said they might look to add other experts in this area.
"We’re so early in the process that we can’t make decisions yet on repair or replace," she said.
In response to a question as to ownership, Donahue said, while it's very early in the process, "If it was a tunnel it would probably be an SDOT owned and maintained structure."
Donahue said that instrumentation to monitor the current bridge and more work that would normally take years has been done in months.
Phelan said that the TAP has not seen any reason thus far as to why it cannot be repaired.
TAP Key Milestones for Written Recommendations:
• Review and support decision-making for type of repair or not to repair
• Review bridge structure demolition tactics and sequence (if necessary)
• Review of key milestone documents including:
• Type, Size and Location Study (TS&L);
• Key Design Milestones (30, 60, 90%, etc.) including but not limited to estimates and design plans;
• Review and support decision-making in regard to Sound Transit’s bridge plans for WSBLE and the relationship with the West Seattle High-Rise Bridge;
• Input and review of construction delivery method, constructability and construction approach, including impacts during construction
• Review of permitting and environmental documentation
• Review of right of way and access needs (as applicable)
• Review of information provided in response to any specific TAP inquiries deemed appropriate by the panel to investigate or to which a detailed response should be provided
• Other technical documents as needed
Heather Marx, Director of Downtown Mobility for SDOT spoke about the gathering of data regarding the plan to Reconnect West Seattle. That process will involve proposals from each neighborhood affected by bridge closure and and mobility proposals region wide that can increase choices for getting off and back on the West Seattle peninsula. After community input, and any necessary revisions the various proposals can be identified and prioritized. SDOT would then report to the community and begin building the projects and programs.
Reconnect West Seattle Draft Schedule
•Week of June 22: Task Force feedback to SDOT on materials and process
•Week of June 29: Finalize and translate materials
• Week of July 6: Launch website with on-line surveys, share ballots, community-led prioritization starts, SDOT provides briefings, Community Liaisons start outreach
• July 8 and July 22: Updates to Community Task Force from SDOT and Neighborhoods
•Week of August 3: Neighborhood prioritization and survey responses due to SDOT
• August 5: Initial prioritization review with Community Task Force
• August 19: Community Task Force secondary review
• September 2: SDOT presents draft plan to Community Task Force for feedback
• End of September: Final Reconnect West Seattle plan
Traffic Mitigation – Next Steps
• Review approach and materials
• Process to gather feedback
•What are your questions and or feedback on the Reconnect West Seattle process?
•What about the materials? In your initial review do you have questions or feedback on how to improve?
• How can we help you get this process going the week of July 6?
Low Bridge Access policy
SDOT is looking at traffic volumes on the low bridge and Adiam Emery Intelligent Transportation System Engineer for the City of Seattle said they are looking at making data driven dynamic policy with regard to access.
Traffic volume, largely due to the pandemic, is down 53% citywide but the low bridge is close to exceediing the safety threshold at many points in the day. Emery said that the emergency response is impacted with more than 450 cars per hour passing over.
The weekend volumes are near the peak, with close to 300 vehicles per hour and there is no active enforcement on the weekend.
• Chelan 5-Way intersection is the key limiting factor
• Unimpeded emergency access calculated by wait times to get onto the Low Bridge
• SFD and SPD have reviewed and concurred
• SDOT analysis indicates that Low Bridge can accommodate total 400- 500 vehicles per hour in each direction before emergency vehicle access is impeded
• This translates into additional access for ~160 additional vehicles per hour, in each direction
• Any additional access needs to be enforceable when Automated Enforcement begins this fall which will be based on license plate recognition using cameras.
The recommendation for now is overnight access will be open for all from 9pm to 5am and school buses. Coming up for more discussion are vanpools, maritime/industrial workers needing work access close to Harbor Island and the low bridge. Employer shuttles and essential healthcare workers in pandemic response are under further review. The new access will happen "as soon as we can operationalize it," Marx said.
They can only accommodate 160 more per hour and Marx said they want to be equitable.
The next meeting is set for July 8.
Motorcycles on the low bridge should be a no Brainerd. Why is there no mention of it?
It was not discussed in the meeting but is likely being considered.
Seattle has the most arrogant and incompetent leadership in America. Heather Marx in totally unqualified to work on this crisis.
This should not even be a question. We cannot afford to wait to build a new bridge or tunnel. If it is repairable, repair it now and then toll the existing bridge to pay for repairs and the new bridge/tunnel alongside. Any cost/benefit analysis that does not factor in the extra time and costs of all the 100s of thousands that use the bridge, not to mention the affect on surrounding neighborhoods with increased traffic, is the mark of a brain of an unfit and unqualified peraon to be in a position of leadership. I understand due diligence, but this is more than obvious. If the leadership is unable to get this simple decision done, there will be serious consequences.
SDOT is so incompetent they haven’t even done basic traffic counts on the detour route I’m forced to take. All sorts of easy and visible wins like signal and channelization improvements at EB Barton at 35th. Every morning cars pile up here because one car wants to go straight and that screws up the free right that could move lots of cars. Make a dedicated right turn lane here and you would have far fewer cars taking shortcuts through neighborhood streets. Just one example.
can you get some input from other countries engineers like germany Switzerland or Japan that actually know how to do things right the first time. I don't have any faith in this team. Duct tape bailing wire and glue is not a solution. Plus I don't even trust you know the capacity of the lower bridge. That opening mechanism has been problematic for years. Wait till that gets stuck from overload. Please ask for help thus is beyond sdot capabilites. Thank you