VIDEO: City Council told Alaskan Way Viaduct still ‘safe,’ but…

(5:12 PM UPDATE: Just added archived video of meeting – briefing starts about 1 hour, 9 minutes in)

10:38 AM: Click the “play” button to watch, live, as the City Council gets briefed on the Highway 99 tunnel project. Today’s big focus – as previewed in our morning traffic/transportation-news watch – is on how much settling is happening with the Alaskan Way Viaduct and vicinity. The briefing is accompanied by a sheaf of technical information, from the state and the city, which has done its own analysis (and has already issued a news release declaring that the AWV is safe to use). More to come – we’re adding toplines below, as this continues.

SETTLING:
*WSDOT project lead Todd Trepanier reiterates that the Viaduct is safe and that if any information indicated it weren’t, they would shut it down ASAP. But, he later says, data underscores that “this structure needs to be replaced.”

*Daily “automatic surveys” are “recording information all the time”

*So what would trigger a declaration of “this is unsafe”? Councilmember Bruce Harrell asked. Trepanier insisted there is no numerical answer to that, no “x” cracks or “x” inches, but that they keep monitoring and if something looks close to a trigger, they fix it. “It’s complex,” he insists. OK, says Councilmember Mike O’Brien, but “what are they comparing it to?” No numerical answer results. Trepanier mentions “demand and capacity.”

*WSDOT briefer Dave Sowers goes through the slide deck we’ve added below. Says that as long as a specific building, specific water line, etc., settles at same overall rate, it’s OK. Discussion also underscores that multiple entities are monitoring multiple points and not always finding exactly the same thing in (nearly the) same place; Sowers says they’re not yet sure why.

*March 28th inspection for which the Viaduct was closed: WSDOT says quarter-to-half inch of settlement at monitoring spots in Seneca Street vicinity, since last October. CM Sally Bagshaw asks why that area, since not near tunnel pit; WSDOT says they haven’t figured it out yet – it’s not the area where they’ve had settling near Seneca in the past. “Bent 76” (monitoring point) is where some cracks showed movement, they add, and new gauges have been installed. CM O’Brien asks, is the deterioration getting to any certain point such as, the Viaduct could have survived an X quake a month ago but not now? WSDOT’s very technical answer does not hit a certain magnitude but does mention that despite the “large cracks” they believe it would be OK in a “108-year event” quake.

*Water main on Western in Pioneer Square to be replaced ASAP – design 90% done – will take about 8 weeks

*City’s technical analysis (second slide deck below): Bottom line, the city wants another analysis before tunneling resumes, since some parts of the Viaduct have already hit the inch-or-so of settling that it was expected to be able to withstand. They also would like to know what magnitude of quake the Viaduct is expected to be able to handle, currently, and whether more strengthening might be in order. Are we approaching a point at which the Viaduct would have to be closed? Councilmember Tom Rasmussen asks. Not necessarily, says SDOT.

SLIDE DECKS:
*Here’s the WSDOT presentation:

*Here’s the city’s technical-analysis presentation:

*Here’s the Seattle Public Utilities presentation (including the water-main-replacement plan):

OTHER PROJECT-RELATED POINTS:
*Seattle Tunnel Partners is making progress on machine-repairing project, says WSDOT, but “still too soon” to set or guess at dates for resumption of tunneling. Won’t be the “budget-breaking project” (some have feared), Trepanier says

*No rescheduling yet for the sign-related work that WAS going to shut down 99 lanes north of the Battery Street Tunnel for a while

19 Replies to "VIDEO: City Council told Alaskan Way Viaduct still 'safe,' but..."

  • Diane April 13, 2015 (11:29 am)

    watching on seattlechannel TV channel 21

  • Matthew April 13, 2015 (12:31 pm)

    If a threshold for “unsafe” isn’t defined, how can we trust that the AWV is currently safe? Basically all we’re getting here is “trust us, it’ll be fine,” until something catastrophic happens. I’d like to know that some metric other than “# of fatalities” will drive the decision to close the Viaduct.

  • Joe Szilagyi April 13, 2015 (1:11 pm)

    Does WSDOT publish safety thresholds for OTHER pieces of infrastructure, beside the Alaskan Way Viaduct?

  • wetone April 13, 2015 (1:13 pm)

    What happened to the hard numbers WSDOT/STP had for allowable movement/sinking when this project started. I thought it was around 2″ ? Is the new area that’s sinking near where they are working on waterfront rebuild, with pile/plate driving going on ? It’s starting to look more and more like there was nothing really wrong with the AWV if it can take all this movement/settling and still be safe to use ? more and more like the city just wanted the land for their wonderland and income….

    • WSB April 13, 2015 (1:24 pm)

      Much of that was discussed in the briefing; the briefing participants really just kept repelling the question of whether there were certain numbers that would “trigger” a declaration of danger, a closure, etc., continuing to insist that they are measuring possible trouble spots in other ways such as certain cracks, and taking action before those trouble spots lead to, well, more trouble. Sorry I was not able to transcribe it completely but we’re watching Seattle Channel closely for the archived video on this one. Also, I know Seattle Times transportation reporter Mike Lindblom was following up post-briefing at City Hall, and we’ll link to his story when it’s available. – TR

  • Kipseawa April 13, 2015 (1:33 pm)

    I’m less worried about cracks and it crumbling than I am about it just plain falling over. Have you seen how far the south end of it tips towards the east? Right at the curve it seems as though that dip is getting more slanted as the years go by an noticeably more as of late. The concrete panels on the side aren’t even flush anymore.
    Anybody address that at the meeting?

  • ChefJoe April 13, 2015 (1:37 pm)

    The Geotechnical Baseline report from before they started drilling is here: http://www.shannonwilson.com/files/GBR%20for%20AWV.pdf

    On what’s marked as pg 482 they had a Group A where buildings required pre-mitigation and 0.5-0.75″ of settlement was allowed/anticipated and a Group B where no pre-mitigation was needed and 1″ of settlement was set as the limit.

    The report doesn’t say what happens (or who gets sued) if things exceed the limits.

  • PG April 13, 2015 (2:09 pm)

    Are there plans in place to keep traffic moving in the event the viaduct does need to be shut down before the scheduled date?

    • WSB April 13, 2015 (3:34 pm)

      Yes. I don’t have the link handy but that’s been the subject of previous City Council (and other) discussions, will add a link when I get a chance.

  • David April 13, 2015 (3:50 pm)

    Yes, it’s been settling and cracking for a decade (more). It’s largely why we’ve had a debate about replacing it for many many years (long before the tunneling project actually started). It’s why we’ve had these “annual” shutdown inspections for years. Whether surface streets, cut & cover, rebuild a new viaduct, or deep bore tunnel, it was going to be torn down SOON anyway. I mean if pumping water out of ONE single 120′ deep pit “near” the structure can damage it (similar to what’s done with every single downtown “high rise” built with their large underground base/garages), then it’s supports are obviously not sitting in bedrock but loose watery soil and they aren’t stable anyway. The sooner it’s gone the better!

  • K. Davis April 13, 2015 (4:59 pm)

    @wetone … You’ve got to be kidding me. You refer to some anecdotal notion that “gosh, with all the work going on around it, the viaduct is still standing so it must be safe”? Please … a little reality here.
    .
    A 6.0 earthquake – not even a big one – on the Seattle Fault would collapse that structure in a heartbeat. Are you suggesting we gamble the 6.0 (or worse) won’t happen?

  • dbf April 13, 2015 (5:11 pm)

    2001 Nisqually quake 6.8, still standing.

  • K. Davis April 13, 2015 (6:37 pm)

    @dbf … Sigh. Read slowly and pay attention. I said 6.0 on the Seattle Fault – which runs right through the heart of Seattle.
    .
    The Nisqually quake was epicentered 50 miles away. .
    Please deal in facts.

  • Someguy April 13, 2015 (6:54 pm)

    PG, hello and welcome to Seattle. I assume you are new to the area when you ask about plans to keep traffic moving. Let me summarize. There is no plan. More busses. Yadda yadda yadda.

  • dbf April 13, 2015 (10:40 pm)

    Ok Davis, take another sigh and allow some oxygen to the brain, Seattle fault first started research in 92, first guesstimated quake a.d. 900-930. Could something happen… Yeah… In that unfortunate instance, a tsunami in elliott COULD surge as high as 6’7″… Covering tunnel entrance and a lot of sodo. But who knows what hundreds of years of speculation can bring.

  • dbf April 13, 2015 (11:15 pm)

    @Davis, in your scenario, most of downtown and surrounding areas would be devastated. Where would you rather be in such an event? Underground watching the water roll in, or above the surface with at least a chance of allowing your survival?

  • phil dirt April 14, 2015 (6:27 am)

    Most of the structures on the waterfront sit on the rubble from the 1889 fire, sawdust from Yesler’s Mill and the fill left over from leveling First Hill. Nobody should be surprised that the viaduct is sinking, especially with bertha grinding away. Hopefully, the DOT keeps a very close watch and is ready to close the viaduct at the first sign of real necessity.

  • JVP April 14, 2015 (3:50 pm)

    @dbf Tunnels are far safer than bridges in earthquakes. Look at the 100+ year old train tunnel under downtown and how well it’s held up over the years. Now look at all of our 50+ year old bridges.

    The tsunami you speak of is much lower likelihood than an major earthquake, which is a near certainty.

    I know the popular thing to do is to pigpile onto those saying the tunnel will never get done. But it’s the right thing to do in the long run, and it’ll get done.

    The viaduct is a death trap, as are the elevated parts of 520. I certainly don’t want to be on either of those during a quake. I’d consider myself fortunate if I was in the tunnel (or really any tunnel) in a big quake.

    They’re past the hardest part, past the worst soils, and they’ve shaken down the machine and discovered its weak points. Yeah, not a popular thing to say, I get it.

    It’ll get done, probably a few percent over budget, and it’s the right thing to do for the city and the region as a whole.

  • k.Davis April 14, 2015 (4:14 pm)

    @dbf … Actually, a comprehensive analysis has been done about both the likelihood and severity of a moderate (6.0-7.0) earthquake on the Seattle Fault – this was done 10years ago by a prominant Seattle geotech firm. And yes, if that event happens, much of the Port will be damaged and older (pre-seismic) areas downtown will be seriously damaged. Our modern skyscrapers should do okay. It will be much like the Kobe quake.
    .
    But I digress – is your point that because other areas will suffer damage, the viaduct’s inevitable collapse (and the significant loss of life with it) is just an acceptable outcome? Or that your illusory tsunami (speaking of statistical rarities in Puget Sound) would hit a surviving viaduct (you see, tsunamis are created by earthquakes … by the time the tsunami hits, if such were to occur, the viaduct has already collapsed).
    .
    But back to reality – if you knew what you were talking about – you’d know that the statistical likelihood of such a 6.0-7.0 quake on the Seattle Fault occurring in the next 50 years is actually pretty high. Certain? No – no one can say that. But likely – yes.
    .
    And hell yes – I’d much rather be in the tunnel when that quake hits. JVP is exactly correct – the tunnel will be about as seismically safe a place to be and certainly exponentially safer than the viaduct.
    .
    So … yeah … reality.

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