‘One inch of ground settlement’ detected for Alaskan Way Viaduct, tunneling-machine repair pit

(Added: Recent WSDOT photo of access pit, shared via Flickr)
5:13 PM: WSDOT says it will be inspecting the Alaskan Way Viaduct and vicinity this weekend after detecting more ground settlement. Seattle Times (WSB partner) transportation reporter Mike Lindblom reported it earlier this afternoon, and now WSDOT has this statement on its website:

Public safety is our top priority, which is why we installed a state-of-the-art settlement monitoring system as part of the SR 99 Tunnel Project. Recently, that system detected approximately one inch of ground settlement near the pit Seattle Tunnel Partners is building to access and repair the tunneling machine. We have also seen the same amount of settlement on the Alaskan Way Viaduct; the amount of settlement lessens in the surrounding area.

Some settlement was expected during tunnel construction and while the tunneling machine repair work was underway. This settlement appears to have occurred in the last month.

We have observed no new damage to the viaduct nor have we observed any effect on buildings or utilities in the surrounding area. WSDOT crews are conducting additional surveys this weekend to verify this information, including an inspection of the viaduct and a visual inspection of the adjacent areas.

While we are conducting this additional work, we are confident that there is no risk to public safety. We will provide an update early next week.

Even before the tunneling project began, Viaduct managers had noted ongoing settlement, usually described as minor (as in this 2010 report). Nothing about settlement was mentioned at the regional stakeholders’ meeting we covered last Monday, but we imagine it’ll come up when the City Council’s Viaduct Committee meets early next week.

6:08 PM: We asked WSDOT spokesperson Laura Newborn if this is the reason the Saturday night/early Sunday Viaduct closure was expanded to both directions, and she confirmed that was done “so extra survey work could be completed.”

26 Replies to "'One inch of ground settlement' detected for Alaskan Way Viaduct, tunneling-machine repair pit"

  • HeyYa December 5, 2014 (5:20 pm)

    Why no link to the Seattle Times story? Weak.

    • WSB December 5, 2014 (5:22 pm)

      Published this without links to get it out, pulling up the links now (Times is paywalled so I have trouble reading it these days). If you have read the site before, you know we link like crazy.

  • HappyOnAlki December 5, 2014 (5:50 pm)

    Oh, come on, HeyYa — “weak”? This is a free service, y’know . . ..

    • WSB December 5, 2014 (5:53 pm)

      That link and several others already have been added. Also coming up, a bit of followup since the WSDOT’s statement.

  • Mike December 5, 2014 (6:11 pm)

    Strange – haven’t heard from the tunnel cheerleaders for quite some time now.

  • Tbone December 5, 2014 (6:25 pm)

    Just bury it. Surprised that for the amount of time and money that’s gone on already that the viaduct coudn’t have been retrofitted and running smoothly (with 3 to 4 lanes) as opposed to the soon to be 2 each way if the tunnel gets completed. Without ongoing biweekly closures of it…. Ridiculous BS, really. The people who plan this are the worst sort of knuckleheads ever…

  • dex December 5, 2014 (7:13 pm)

    Have noticed a bigger gap on upper deck around that spot. Hope they didn’t mess that up too.

  • Rick December 5, 2014 (7:38 pm)

    Looks like we’ve got our own “cashole”.

  • miws December 5, 2014 (8:21 pm)

    Why no link to the Seattle Times story? Weak.
    Comment by HeyYa


    Why no respect for the hard work WSB does? Lame.



  • Mike December 5, 2014 (8:25 pm)

    Glad it’s being tracked

  • Joe Szilagyi December 5, 2014 (8:26 pm)

    Interesting tweet I saw earlier: https://twitter.com/TunnelWatch/status/541031061396783104
    I wonder how those numbers break down today.

  • Admiral935 December 5, 2014 (9:17 pm)

    Curious how close the seawall project is to this and if the seawall proj has any sinkage of its own. The Times article mentions that Historic Buldings have settled (this week?) since the Bertha “pit”. I can’t fathom how anyone including soil “experts” has any degree of confidence about this pit/sinkage tollerance at this point. Glancing at the tweeet, it seems they are at, or may as well be, at limit on sinkage.

    Good luck to us all.

  • SandySod December 5, 2014 (9:26 pm)

    I know I’m not an engineer but I’m a native – and we all know downtown Seattle is built on fill and with all the big water (the Sound/Duwamish) near the dig it just seems like a huge ‘duh’ that there is settlement. Not a great place to dig. Mother Nature wins.

  • schwaggy December 5, 2014 (9:32 pm)

    They’re going to have to fill that rescue pit, right? That alone seems daunting.

  • Twobottles December 5, 2014 (9:41 pm)

    “I know I’m not an engineer…” . Enough said.

  • JeffK December 5, 2014 (10:20 pm)

    Change is a constant, embrace it.

    Djidjila’letch to Pioneer Square:

  • Bertha schmertha December 5, 2014 (10:23 pm)

    Happy 1 year anniversary of Bertha being stuck in place! Cue the tunnel cheerleaders to tell everyone to calm down. Everything is going according to plan and there will be no further problems or cost overruns.
    I’m just waiting for it to go another 10% of the way and get jammed under an building where it can’t be accessed.

  • WSobserver December 5, 2014 (10:39 pm)

    You can often view paywalled material through Google cache, but I don’t know how to work it….check Reddit r/Seattle, there is often a poster named googlechacheguy who will post cached Seattle Times articles for your viewing pleasure.

    Without the cache, here’s a link to the article on Seattle Times, “Viaduct sinks an inch as workers dig to repair Bertha”

    • WSB December 5, 2014 (10:48 pm)

      The original story by Mike was in the ST’s “blogs” domain and I couldn’t find a cached version (I know that workaround too) earlier. Did just find a cached version of the new one and read it – the one linked in your comment, with lots of updated info.

  • Smitty December 6, 2014 (8:26 am)

    I wonder how many of the “keep calm and carry on” crowd is starting to have their doubts.

    This is just one major setback after another. Just wait until Bertha gets stuck under downtown!

    Cut our losses.


  • Sue December 6, 2014 (9:12 am)

    Re the paywall on Seattle Times, just clear your cookies – I do it all the time when I get locked out, and get back in without a problem.

  • beef December 6, 2014 (10:34 am)

    paywall – open in an private/incognito window. :)

  • wsea December 6, 2014 (10:42 am)

    You can also view the times website via incognito or private mode in your browser.

  • ChefJoe December 6, 2014 (10:51 am)

    Sue, incognito mode (or a private window) will not store cookies in the first place. The cookie that ST uses that’s the target of your mass deletion is from seattletimes.com and is called “content_meter”.

  • Laura December 8, 2014 (7:35 pm)

    Quoting Kevin O’Leary of Shark tank “Stop the madness”! I am sure the outdated overdue viaduct will take a licking and keep on ticking. I have been stopped on it a few times and I am sure everyone has as well and while I am sitting taking notes I find myself praying I will get off soon.

Sorry, comment time is over.