SDOT throws a surprise wrinkle into the West Seattle Bridge decision
After more than 200 days since the Seattle Department of Transportation closed the West Seattle Bridge they've come up with a new potential solution to fix it. The new wrinkle comes a week before Seattle Mayor Jenny Durkan was set to announce her decision to commit to a repair or replacement. The information is being met with a range of reactions from wait and see to complete skepticism.
SDOT has, at the suggestion of contractor HNTB, now suggested a Tied Arch Bridge replacement modeled after one built at Lake Champlain in 2011 could be the answer and said it might only take three years to complete.
In an "in-between" meeting of the Community Task Force, who through a series of more than ten weekly meetings looked at six different options as part of the "Cost Benefit Analysis" (CBA) process SDOT said the idea was appealing because the arched section could presumably be built off site then barged in and lifted via crane into place. That CBA is set to be delivered on Oct. 19.
But the idea has not gone through the same vetting or cost benefit analysis as the previously discussed options. Even those proposed solutions would need to go through a Type, Size and Location study before full costs could be determined.
Task Force Co-Chair and former Seattle Mayor Greg Nickels said, " I am pleased to see the Rapid Replacement concept. Having lived through the earlier bridge saga (as newlyweds Sharon and I bought our first home in West Seattle in April 1979), I have great sympathy for those having to make the trip to the other side every day and to the communities affected by the huge number of vehicles now affecting them. The appeal of the repair option is directly attributable to the (relatively) short time frame despite the uncertainties and risk. The urgency of reconnecting West Seattle in a timely manner has been a consistent message to SDOT during the Task Force’s deliberations. The rapid replacement concept certainly needs to be scrutinized as have all the replacement options, but it does provide some hope of a fully functional replacement in far less time than the previous replacement options and is responsive to our concerns."
Port of Seattle Commissioner Peter Steinbrueck said, "I would say that, with the reopening of T-5 in Spring 2021, and phase 2 in 2023, it’s extremely urgent that capacity be restored. I have no confidence that a “quick bridge“ replacement is at all possible."
Lora Radford, Executive Director - West Seattle Junction Association said "The idea of a rapid replacement is a rumor that recently surfaced this week. I'm anticipating more discussion around this potential option at the next Task Force Meeting"
CTF member and owner of Peel and Press in the Morgan Junction Dan Austin said, "It is clear that SDOT doesn’t want to be responsible for a repair even though the Technical Advisory Panel (TAP) says it is achievable. I get that they are scared of being wrong and having the political and public blowback. That fear doesn’t make it the right decision to not repair the bridge. If the cost of repair are astronomical then it’s a different story. Without the numbers in hand yet, we cannot make an informed decision. I am always skeptical of ideas that sound too good to be true being introduced this late in the game. This new concept needs serious vetting and has a lot of obstacles ahead of it that will need to be run through some risk assessment. I hope everyone keeps an open mind, that is free from predetermined agendas while we get all the pertinent information."
The Immersed Tube Tunnel (ITT) idea that stirred so much interest around the city was essentially rejected in attributes assessment issued by SDOT who suggested, without any explanation that it would be the "most expensive" and would take ten years to complete. Tunnel proponent Bob Ortblad countered that SDOT's estimates as to cost and construction time were wildly mistaken noting that the ITT in Vancouver B.C. was built in 2 years in 1959 and a new bridge over the Fraser River was recently rejected in favor of another ITT there. But more seriously, Ortblad points out that the tied arch bridge concept being floated by SDOT is not possible.
Ortblad said, "Let’s compare apples to apples. The Lake Champlain Bridge is a narrow two-lane bridge with a 402-foot center span. Its foundation is a short distance to bedrock. Vermont had a magnitude 4.0 earthquake in 1953.
He explained, "SDOT and HNTB propose saving several years by fabricating a 5,000-ton, 590-foot center span off site, barging it between the bridge piers and lifting it into place. However, SDOT and HNTB forgot to check the width of the Duwamish River channel under the West Seattle Bridge. The channel is only 200 feet wide so it is impossible turn a 590-foot bridge span into position under the bridge piers. No crane can make this lift; it requires dozens of hydraulic jacks on the bridge piers."
Ortblad continues, "A new West Seattle Bridge will need to be six lanes with a 700-foot center span making it five times larger than the Champlain Bridge. The West Seattle Bridge sits on 200 feet of Duwamish alluvial mush. Piles over 200 feet long reach for compacted glacial soil. The bridge also is directly over the Seattle Fault. The 2001 Nisqually 6.8 earthquake damaged the West Seattle Bridge and was a thousand times stronger than Vermont’s last quake.
A better comparison is the new Port of Long Beach, CA Bridge. It is six lanes like the West Seattle Bridge. It crosses a 400-foot ship channel; the Duwamish has a 500-foot ship channel. The Long Beach Bridge was costly because was designed to withstand a major earthquake. The Long Beach Bridge took ten years to design and build. At a cost of $1.5 billion, it was over budget by $550 million. The designer was HNTB, the same firm the Seattle Dept. of Transportation has hired to design a new West Seattle Bridge.
An Immersed Tube Tunnel (ITT) is the fastest (3-4 years), least expensive, most environmentally sensitive, earthquake resistant, and only light rail accommodating solution to reconnect West Seattle."
Bridge Activist group West Seattle Bridge Now has been in favor of completing the repairs and restoring traffic to the structure as soon as possible. Their focus is both economic and technical (through the input of member Adam Ludwig whose detailed explanation of how the bridge could be repaired quickly and securely was covered in an OpEd in Westside Seattle Sept. 16.
“This is a choice between repair and replace. The community clearly wants repair and we don’t think SDOT is listening.” said WSBN member Joe Turcotte.
JenTemple, CTF and WSBN member said, “SDOT still hasn't given us numbers, but we know they haven't factored in the economic impact on our community. We simply can't afford to wait 6 years, or even 3 years.”
WSBN said in a statement:
$25 million (or less) and open in six months or less.
Someone connected to SDOT, with full knowledge of the state of bridge and access to the information the public has been denied, told us directly that an assessment of the bridge exists that restores full usage of the Bridge within six months and for less than $25 million…
And they came to us because it is mind-boggling to them that the decision hasn’t been made to do that. They are out there right now “repairing” the bridge, in their terms stabilizing it. The contract with Kramer for the stabilization work was $17 million, but was scaled back to $14 million.
When the stabilization is done, and just before they want to demolish it, it could be open. It could be “fixed”, the bridge that they want to demolish will be drivable . And if they beefed that up, just a little bit, like 20%, the roadway would likely fulfill its expected life expectancy, lasting another 40 years. All of the experts agree with that assessment.
Why the replacement option doesn’t make sense:
The West Seattle Bridge is over 2 miles long from Fauntleroy to I-5. The center span that would be new is only 870 feet of that. So building a “new” bridge that can last 75 years is not true. The center span could last 75 years, but the approaches (the elevated roadways/bridges that lead up to the new span) will be halfway through their lifespans. So if the earthquake they want the replaced bridge to be able to withstand would potentially leave all the approaches laying on the ground… leaving us with a beautiful new “bridge to nowhere!”
Right around the corner from the West Seattle Bridge is Avalon Way. This a road that SDOT decided to repave and rechannel a couple of years ago. The businesses, and there are only a few, sounded the alarm. The work was largely elective, it wasn’t critical infrastructure, and these businesses got together and told SDOT the financial impacts were going to be extremely hard to survive. Well SDOT charged ahead anyway and sure enough it took them over a year to repave a relatively small stretch of road. Multiple small businesses there died and those small businesses are gone forever.
Do we really believe that SDOT can parlay their experiences on Avalon into a new replacement bridge in less than three years? They couldn’t repave a road in nine months. How many West Seattle small businesses will die because of their agenda?
We don’t need a new bridge, we need the current one repaired."
The next Community Task Force meeting is set to discuss the Tied Arch idea, as well as review the Cost Benefit Analysis when it meets on Oct. 21.
We should be so grateful for Mr. Ortblad. While SDOT/Herbold and the City try to ram through a bridge replacement, Mr. Ortblad brings science, common sense and whole career of engineering experience to call the bureaucrats on some truly questionable, if not downright dishonest, positioning. If it wasn't for Bob I think the decision for a 6+year rebuild would already be underway and our wonderful community would be left to suffer the devastation repercussions.