Following up on this morning’s news that the Highway 99 tunnel machine had made it as far into the repair pit alongside the Alaskan Way Viaduct as it needed to go, WSDOT has released the 1:14 time-lapse video embedded above. According to this morning’s update, taking its cutterhead apart to be lifted out for repairs is expected to take weeks.
The Highway 99 tunnel machine is back on the move, according to WSDOT. It’s protruding further into the repair pit as it moves forward; WSDOT says five more tunnel rings have to be built behind it before it stops short of the north side of the pit. What happens after that is described in today’s update on the Highway 99 project website. You can get the newest view by clicking the camera at center-left on this page (that’s where the image at left is from).
(Image downloaded from repair-pit camera after 5 pm today)
22 feet down, 35 to go for the Highway 99 tunnel machine, one day after it broke through the wall of the pit from which its cutterhead will be lifted for repairs. But it’s idle for now, as explained in this late-afternoon update from WSDOT:
After a few days of steady digging, Seattle Tunnel Partners is taking a break from mining so crews can clean out the bottom of the access pit. As expected, a mixture of dirt, concrete and water came into the pit along with the tunneling machine during Thursday’s breakthrough. Crews are using vacuum trucks and other tools to remove the material.
Once Bertha’s cradle is cleaned off, crews will continue moving the machine forward. Bertha must travel an additional 35 feet before STP and manufacturer Hitachi Zosen can begin the disassembly process. Since mining resumed late Tuesday, Bertha has moved nearly 22 feet.
Meantime, the SDOT director’s report we mentioned in an earlier story includes a few related notes. For one, SDOT director Scott Kubly writes, the city’s plan to independently evaluate the Alaskan Way Viaduct is proceeding: “Initial consultant scope, to be completed by early to mid-March, focuses on technical review of 2010-2014 studies of the viaduct and serviceability/safety for use of the viaduct structure.” Later in the report, he writes, “Bridge engineers responded to a report that concrete had fallen off the Alaskan Way Viaduct near Seneca Street. No significant defect was noted and it appears to be the continued minor deterioration of the aging structure.” (The date when this happened wasn’t mentioned.)
11:39 AM: If you’ve been on the Alaskan Way Viaduct this morning and noticed a dust cloud – the Highway 99 tunneling machine is “preparing to break through” the wall of its repair pit, according to a Twitter update a few minutes ago. Earlier this morning, WSDOT published a web update saying the machine had moved 14 of the 20 feet it needs to go to break into its repair pit. It had warned that they expected the machine to overheat and have to stop down, but aside from a stopdown reported last night so other work could be done in the pit, there’s been no word of that happening. WSDOT says it’s switched the pit camera to more frequent updates – every five minutes – so you can check in here (left-center frame).
12:44 PM: And while we were away from the desk for a bit:
The top of my cutterhead has broken through the wall. I'll dig 2 more ft. before stopping to build a ring. pic.twitter.com/SVcThsimnv
— Bertha (@BerthaDigsSR99) February 19, 2015
Online, WSDOT adds:
This is just the beginning of the repair effort being led by Seattle Tunnel Partners and manufacturer Hitachi Zosen. The machine will continue to move forward in 6 ½ foot increments, stopping to build rings on its way into the pit. When the front end of the machine is fully exposed, crews will begin the disassembly process. STP has told us that taking the machine apart and lifting it to the surface will take significant time and effort.
ADDED 5:22 PM: WSDOT offers this video including the first glimpse of the machine’s cutterhead (most visible around 1:15 in):
(UPDATED LATE WEDNESDAY AFTERNOON with progress report)
9:47 AM: Last week, WSDOT said the Highway 99 tunnel contractor would likely start the process this week of trying to get the tunneling machine to move 20 feet ahead so its damaged cutterhead can be pulled from the 120-foot-deep pit dug next to the Viaduct. This morning, there’s word the process has begun. As of 7 this morning, according to WSDOT’s announcement, the machine had made it about three feet forward:
The machine must mine through 20 feet of unreinforced concrete to reach the pit. The duration of this effort will depend on the machine’s ability to mine through the concrete while operating with a damaged seal system. STP anticipates the machine may overheat, as it has during their most recent attempts at mining. If the machine becomes too hot, they will take a break for it to cool down before resuming.
The image above is from the WSDOT page displaying several “live” construction cameras. (P.S. The south side of the pit, where it’s expected to break through, is on the left side of the photo.)
4:32 PM: WSDOT has just posted another update – saying the machine has now gone six feet.
(Added 9:27 pm: New image from camera over ‘access pit’ built to retrieve part of tunnel machine for repairs)
Survey crews have confirmed that the Alaskan Way Viaduct between South Main Street and Railroad Way South has settled up to ¼ inch in the past month. Our bridge experts are confident this minor, uniform settlement does not pose any new safety risks to the public. The viaduct remains vulnerable to earthquakes, but it is still safe for everyday use. If we had any reason to believe the structure was unsafe, we would not hesitate to close it.
These latest measurements only apply to this section of the viaduct. We have not measured any similar trends elsewhere on the viaduct, in nearby buildings or the ground surface. We expect the viaduct will continue to experience minor settlement until it is removed. Viaduct settlement has made headlines in recent months, but it’s important to remember that this isn’t a new issue. The viaduct has been settling for years, as you can see in our inspection log. Hundreds of monitors have been installed in the ground and on the viaduct to help us monitor settlement, and we will continue to keep a close eye on the structure’s condition as construction continues.
WSDOT also says the operation to move the tunnel machine into the repair pit could start within days:
(At 3:39, WSDOT’s video shows excavation on its final day, today)
Just in from WSDOT, the latest Highway 99 tunnel news: The pit being dug to lift out the tunneling machine’s damaged cutterhead has reached the desired depth, 120 feet.
… Approximately 20,000 cubic yards of material was removed from the ground over the course of excavation, which began in mid-October. With excavation complete, crews can begin construction of the concrete cradle at the bottom of the pit. The cradle will support the machine after it moves through the pit’s southern wall, which is about 20 feet thick.
STP plans to tunnel through the concrete wall. The length of time it takes Bertha to reach the pit will depend largely on her ability to mine through and digest the concrete. If she’s unable to mine through the wall, STP will create an opening from within the pit to give her an unobstructed path forward. Once inside the pit, crews will use the massive red gantry crane … to hoist the front end of the machine to the surface for repairs.
Today’s update also says, “Settlement levels near the pit remain stable.”
Meantime, for more info on that giant crane – which you’ve likely noticed right next to the Viaduct downtown – check out Seattle Times (WSB partner) transportation reporter Mike Lindblom‘s story from two weeks ago.
Update: Council’s longer-than-expected briefing on tunnel/Viaduct, and the 2 words repeated over and overJanuary 12, 2015 at 1:02 pm | In Alaskan Way Viaduct, West Seattle news | 41 Comments
(4:09 PM UPDATE: Archived video of the meeting now added above. The Viaduct discussion starts at 1 hour, 37 minutes in – you can drag the playback bar there)
1:02 PM: The City Council is already an hour and a half past the time it expected to conclude this morning’s “briefing” meeting. WSDOT has been on the hot seat since 11:15 am on the state of the tunnel-repair project and issues including a letter from SDOT in response to a report from WSDOT engineers around the time the repair pit’s status became an issue a month ago. Much discussion focused on the phrase “catastrophic failure” relating to the repair pit work – though it’s been reiterated over and over again that the Viaduct is safe, councilmembers want more assurance. Two more agencies are coming up now – SDOT and Seattle Public Utilities – so we’re putting the live window above, and will be adding the highlights of notes we’ve been taking (plus other coverage links) along the way.
1:29 PM: The meeting just adjourned. Here’s what’s transpired so far:
–Much discussion about the letter sent by SDOT to WSDOT and the engineering report that led to it. As far as we can tell, this was first reported by Sydney Brownstone of The Stranger. WSDOT opened its part of this morning’s meeting by sternly declaring that the city letter took the phrase “risk of catastrophic failure” out of context. This was repeated over and over again; the City Council, however, got stern right back – Councilmember Kshama Sawant, for example, noted that she formerly worked as an engineer, and engineers don’t use that phrase for no reason. Council President Tim Burgess asked WSDOT if it had the December 11th report handy, and when told, “yes,” stopped the meeting briefly so it could be given to a clerk who immediately made copies for the council. We’ve asked WSDOT for the document as well, and will add it here as soon as it comes in. (ADDED: Here it is; the “catastrophic failure” mention comes in the final paragraph. Note that WSDOT says this was a “draft” and has also sent a 12/19 “final” version [added]- here’s that one.)
Later in the meeting, WSDOT suggested that because of this “out of context” quoting, it might restrict city access to a system in which it keeps these reports, and several councilmembers voiced disbelief at that.
MORE AFTER THE JUMP…
For the first time in more than two weeks, we have an official update on Seattle’s most closely watched pit – the one intended to reach the Highway 99 tunnel machine, so its cutterhead can be retrieved and repaired. WSDOT published the update this afternoon, saying that its contractor Seattle Tunnel Partners resumed digging today, and that: “Settlement levels near the pit have remained stable for more than six weeks.” The pit is 3/4 of the way to the 120-feet depth at which STP says it will pour a platform for the front of the machine to rest on, after it is turned back on to advance a short distance into the pit. Timeline? Nothing new yet, says WSDOT; you might recall, the most recent ballpark-guess tunnel-opening date was August 2017.
P.S. Reminder that seawall-and-tunnel-related work downtown will result in access changes at Colman Dock and Water Taxi Pier 50 starting tomorrow.
Tunnel updates: Opening no sooner than August 2017; access-pit digging on hold again; new ‘settling’ infoDecember 22, 2014 at 2:35 pm | In Alaskan Way Viaduct, West Seattle news | 75 Comments
That’s an estimate made by the contractor Seattle Tunnel Partners BEFORE the recent discovery of “settling” in the area; WSDOT just disclosed the date today, as part of a general pre-holiday update. The update also says that while no new settling has been detected near the pit being built to retrieve the cutter head of the broken-down tunneling, machine, settling elsewhere “is greater and farther reaching than anticipated. Engineers are still evaluating whether other factors are involved that could explain the discrepancy. We will continue to conduct daily inspections of the viaduct and watch the survey data closely as STP moves forward with their work. As we write this, we’re on a conference call with other reporters and reps from WSDOT and STP – we’ll be adding more details shortly.
ADDED 3:19 PM: The conference call is over; from WSDOT, it included project executive Matt Preedy and spokesperson Laura Newborn, and from Seattle Tunnel Partners, executive Chris Dixon, plus local/regional/national reporters.
Among the many points of note:
-The August 2017 date that debuted today was described as coming from the “October update” by STP. We asked why it wasn’t mentioned before, not even during the official stakeholders’ briefing (at which we were the only news org on hand) in early December. STP explained that these updates – which WSDOT now plans to make public – take several weeks to assemble, so the “October update” is just being parsed now. (Which means, they acknowledged, we won’t know full details of the “November update” – which would still not include this month’s turbulence – until January, and so on.)
-The schedule will remain “dynamic,” said WSDOT’s Preedy, until the tunneling machine is back in operation. (In other words, even the new August 2017 date is nowhere near set in stone.)
-Excavation of the pull-the-cutter-head-out-for-repairs pit is on hold now for two weeks, and not expected to resume until early January. Digging stopped on Friday, about three days after WSDOT had said it could resume. Some non-structural pilings, explained in the official online update, are being pulled out before they start going to the next level. STP’s Dixon explained that digging had been done in stages, about six feet at a time, before an evaluation of where everything stood. At the completion of the most recent stage – to 90 feet in pit depth, aka “-74 in elevation” – they decided to pause for piling removal.
-Would it have been quicker, in hindsight, to approach the tunnel-machine repair project from the south/interior? STP insisted it’s happy with its choice to build the pit to try to hoist the cutter head out, even though it’s of a magnitude that has never been done before, given the machine’s record size, etc., and has “been more difficult than anticipated.”
-The settlement of the Viaduct itself, when recalculated as explained in the online update, will likely be a bit less than estimated, but the settlement causes in the area remain a mystery, and an investigation continues.
-As for the big issues – who pays for all this unanticipated work? – the state continues to point out that this is a “design-build contract” and that STP is expected to do whatever it takes to fulfill that. Pressed on certain specifics, WSDOT’s Preedy said he didn’t think it “appropriate for either party to speculate” on how it’s all going to be worked out.
-About the “70 percent complete” recent proclamation, today’s answer seemed to mostly boil down to, that’s the percentage STP has been paid.
P.S. To see the “October schedule” from which the August 2017 open-to-traffic projection was pulled, go here. WSDOT also has published the September schedule, which also seems to project that same month (albeit a couple weeks earlier than the Oct. “schedule”).
If you’re heading this way from downtown or points north – note that there’s a backup on the southbound Alaskan Way Viaduct from just before the stadium zone, because of a one-vehicle crash. Kim reported it via Twitter:
— Kim Sharpe Jones (@seattlekim) December 21, 2014
No emergency vehicles at the time, but now they’ve been dispatched and reportedly will be checking a toddler for possible injuries.
Today’s Viaduct/Tunnel update: Long FAQ including declaration of disappointment, threshold for ‘mitigation,’ moreDecember 17, 2014 at 5:39 pm | In Alaskan Way Viaduct, West Seattle news | 38 Comments
Today’s WSDOT update on the Viaduct/Tunnel project, posted late today, is a new, long FAQ attempting to answer some of the questions that have come up since the December 5th disclosure of “settling.” Read it in its entirety here. Some of what caught our eye on first look include:
Our contract with STP allows up to two inches of viaduct settlement before mitigation is required. Should it be necessary, a number of techniques could be used to strengthen the viaduct and keep it open to traffic until the new SR 99 corridor is completed. These techniques could include strengthening columns or other areas of the structure to provide additional support. We could also reinforce the viaduct’s foundation as we did in 2008.
Regarding the plan to reach, lift, and repair the tunnel machine’s cutter head, WSDOT writes, “We’re disappointed with STP’s progress to date …” while noting the pit is now three-fourths of the way to the expected 120-foot depth, and expressing optimism that even if the current rescue plan has to be abandoned: “At its core, this is an engineering problem, one that can no doubt be solved.” The FAQ reiterates, “No significant settlement has been observed in the area since Dec. 5.” And as for the biggest concern of all:
Our bridge experts have confirmed that the viaduct remains safe for day-to-day use. If we had any reason to believe it wasn’t, we wouldn’t hesitate to close it. It’s important to remember, however, that the day-to-day safety of the structure does not change the fact that the viaduct remains vulnerable to earthquakes. That’s why it’s being replaced.
(WSDOT photo from last week – assembly of what’s meant to lift tunnel-machine head from pit)
After Monday’s City Council session looking at the latest tunnel-related troubles (WSB coverage here), council president Tim Burgess declared it’s too late to turn back now. So, with no new settlement reported, onward it will go. WSDOT‘s tunnel update for today, just published here, says their contractor Seattle Tunnel Partners has the go-ahead to continue digging the pit from which they hope to pull up the tunnel machine’s damaged cutter head:
Excavation was stopped at WSDOT’s direction on Dec. 12. While no significant ground settlement had been observed since Dec. 5, we suspended excavation to give our team time to gather more survey data and review STP’s contingency plan for turning off the dewatering wells, should that become necessary. We have now reviewed STP’s plan and gathered additional data from the weekend that shows the recently measured settlement has stabilized.
The digging stopped about three-quarters of the way down to where they hope to reach the machine. The red lifting device is under construction (photo above) feet from the Viaduct, roughly parallel with King Street.
(ADDED: Video of this morning’s entire meeting, above)
9:41 AM: Ten days after concerns about “settling” related to the Alaskan Way Viaduct Replacement Project, WSDOT reps are briefing the Seattle City Council right now. Transportation secretary Lynn Peterson says there appears to be “no further settlement” since what was reported a week and a half ago, and no damage to buildings in the area. She says that while this is a “tense moment” in the project, WSDOT firmly believes it’s “less risky” to proceed than to rely on the earthquake-vulnerable Viaduct. She also vows that the contractor, Seattle Tunnel Partners, is being and will be held accountable for what they’re expected to do. And she says they can’t commit to any kind of timeline right now for completion, because the cutter head has to be retrieved for repair first: “This is a design-build contract and we have purchased a tunnel … the fix .. is the responsibility of the contractor. We do not own the machine nor the method” STP chooses to fix it.
WSDOT’s Todd Trepanier tells the council STP was asked to stop excavating, at least temporarily, on Friday, until getting a green light for resumption. He’s getting into more technical points; here’s the slide deck just added to the agenda.
You can watch the briefing live here. After WSDOT reps are done explaining, and answering council questions about, the “settling” situation, city reps are scheduled to talk about the status of plans in place in case a Viaduct closure was needed. We’ll have toplines of that later; you can preview the slide deck (which involves a 2005 plan centered on “what ifs” in case of an earthquake) here, plus a new city update on the “settling” situation here.
11:26 AM: The meeting, originally scheduled for about an hour, has now lasted for two and isn’t likely to end any time soon – again, it’s live at seattlechannel.org. Councilmembers continue to press for more specifics on Viaduct safety – a moment ago, Councilmember Kshama Sawant was asking what size of earthquake would take the AWV down; WSDOT says it doesn’t want to speculate but notes they all believe the structure “is vulnerable.”
11:30 AM: City reps are now coming to the table to discuss the status of plans in case it was determined the Viaduct had to be closed – not just transportation, but utilities.
SDOT director Scott Kubly says the “unified command structure” has been meeting at least once a day to talk about the situation. Seattle Public Utilities says it’s been monitoring utility lines and pipes in the area – they’re using a hydrophone to “acoustically” detect water leaks, as well as using closed-circuit video to watch the sewer lines. The presentation embedded above this paragraph shows all the utility info they’re presenting, including what types of lines are in the Viaduct/tunnel-pit area, as well as the transportation plan that SDOT will discuss shortly.
11:46 AM: Now it’s SDOT director Kubly’s turn, after a council question asking SPU who covers the cost if there are utility problems – answer: the state. Meantime, he says that they are in “good shape” if a Viaduct closure was necessary, because the 2005 plan is updated each year. The “variable message boards” on paths to The Viaduct would be called into action, as would equipment like barricades etc. which he says are “pre-loaded” onto vehicles and ready to go at a moment’s notice, if needed. He is followed by Seattle City Light with its plans. Meantime, the Department of Planning and Development hasn’t heard yet of any buildings that would be deemed unsafe, but if settlement was “a lot steeper in areas,” they have authority to “do various things depending on how much damage we see … (including) ordering vacation of (a) building.”
11:58 AM: Councilmember Tom Rasmussen asks how Metro works into this plan if the Viaduct had to close. Kubly says Metro is “at the table” and they are looking at “how would we speed buses” and “what detour routes would be in place … how (to) add service would depend on length of the closure.” Could the plan deal with all 60,000 people/vehicles that would not be able to use the AWV? Kubly says it would address elements such as possible restrictions on “non-essential construction,” changes in deliveries, and looking at ways to get more people carpooling, using transit, etc. (The funding for extra transit is “already gone,” the council is told.) WSDOT’s Trepanier is asked to come back to the table to answer some questions, such as what if there’s a long-term gap between the Viaduct going out of service and the tunnel coming into service. He says the Legislature made the decision not to use any more project money toward “transportation mitigation” (such as transit).
12:13 PM: The Viaduct discussion is over and the council has moved into a preview of its 2 pm meeting, which will include the White Center annexation proposal. When the video of this meeting is available, we’ll add it to this story.
3:18 PM: Just added the video.
Today’s Viaduct/tunnel pit update from WSDOT: No new ‘significant settlement’; no voids under King St. crackDecember 12, 2014 at 6:28 pm | In Alaskan Way Viaduct, Safety, West Seattle news | 15 Comments
After the ensuing week of various updates, discoveries, and concerns, today’s update is out, and in it, WSDOT says “to date, no significant settlement has been observed beyond the initial settlement we reported publicly on Dec. 5. The viaduct remains safe for travel.” The update also says that so far, ground-based radar hasn’t shown any “voids” under the crack scrutinized on King St. in Pioneer Square on Thursday. (E-mail from WSDOT to reporters adds, “The crack in the middle of King Street has been there for some time, as seen in a Google Maps picture from 2011. Given the absence of prior settlement data on this particular street, it may take a while to fully understand what may have caused pavement to shift.)
Meantime, the City Council‘s agenda for next Monday morning has been revised to start with WSDOT execs’ updating the council on the “settling” at 9:30 am, followed by a 9:50 am discussion with state and city officials about what would happen if the Viaduct had to be closed, short term or long term. The agenda section for the latter item includes this existing document that discusses closure in the context of an earthquake.
(SCROLL DOWN for newest updates)
2:58 PM: That map (click the image to see the full-size version) is the main Alaskan Way Viaduct/Highway 99 Tunnel update so far today, six days after first word that some areas in the vicinity have “settled” more than an inch. You might have seen a version of the map on Publicola this morning; the version released by WSDOT this afternoon has added context and a slightly different color scheme. It shows settling of almost an inch and a half in some areas, but does not show the areas of “uneven” settling, says WSDOT, and the text of their update makes it clear this does not show what’s happened on The Viaduct itself:
Crews from WSDOT and Seattle Tunnel Partners are conducting ongoing surveys of the Alaskan Way Viaduct and ground to determine whether settlement is continuing near the SR 99 tunnel access pit. In general, the surveys include:
Twice daily manual measurements at the bottom of both the east and west columns of the viaduct.
Approximately every other day measurements of deep survey points. These are survey points more than 80 feet underground.
Ground surveys of sidewalks and streets from Alaskan Way to Second Avenue and from Yesler Way to South King Street. Some areas are surveyed twice a day; other areas are surveyed once every two to three days.
Surveys of some buildings. Data is collected both manually and automatically and monitored daily.
The data from the ground surveys and deep survey points are represented on a survey point data map. This map does not represent data from building surveys or the surveys of the viaduct.
The map is a computer-generated approximation to show visually the survey results that were shared with the public on Dec. 5, which indicates approximately 1.4 inches of ground settlement near the access pit and a lesser amount of settlement in the surrounding area. It does not show differential settlement, which is uneven settlement that occurs underneath a particular building or structure.
Lastly, the map does not present conclusions about the effect of dewatering. Additionally, the colors have been modified to better show the change in settlement from high to low.
We asked WSDOT earlier today if the tunnel contractor was continuing with access-pit digging, estimated two days ago to have another day to go before they reached a point where they’d stop to evaluate. The reply said only that the December 9th update still applied. We’ve been watching the “live” construction camera, and the excavation equipment does seem to have been in action as the day goes on.
ADDED 4:15 PM: New development – a crack in King St. downtown, not far east of the “rescue pit.” A briefing by the mayor is expected soon.
(Access-pit camera’s image from 3:20 pm today)
Again today, with the stalled Highway 99 tunnel project under the microscope more than ever before, WSDOT has just published a new update. This time, they’re clarifying the status of the access-pit dig intended to get to the tunneling machine’s cutter head:
Excavation continues on the circular pit (pdf 2.5 Mb) that will be used to access and repair the SR 99 tunneling machine. Seattle Tunnel Partners’ engineers have determined that continuing excavation to 84 feet, an additional 3 feet from the current depth, will not affect when and how the dewatering wells could be turned off. We anticipate excavation to this elevation will take approximately one day, at which time STP will inspect the shaft walls per their quality assurance procedures. Once they reach 84 feet, STP will review survey data and consult with their engineers and WSDOT prior to determining next steps. …
The update (which you can see in its entirety here) also mentions that work continues on the crane intended to lift the damaged machinery from the pit, and on the 1,000 feet of tunnel dug before the machine stopped work one year ago. The latter two points were also reviewed at the project stakeholders’ meeting we covered one week ago downtown, just a few days before WSDOT disclosed last Friday the “settling” that was causing concern, following up with a Sunday update, and then a City Council briefing yesterday.
(TOPLINES: State insists Viaduct safe. Council wants to know specifics of what would make it unsafe. State says it’s up to tunnel contractor to figure out what happens next)
(Screengrab substituted for video window after meeting; will add archived video when available)
2:47 PM: The City Council regularly gets briefed on the Alaskan Way Viaduct Replacement Project, but with the disclosures of the past few days, the meeting under way now takes on extra weight. Watch in the video window above (click “play” for the live stream); we’ll note key points as it goes.
Regarding the “settling,” WSDOT officials say it does seem to have coincided with the “dewatering” process, which they explain involves a series of wells, to reduce the pressure as the contractor dug further down toward 120 feet in depth. This new settling, it’s explained, was detected by a wider swing in the survey area revealing “deep benchmarks” had settled – where they weren’t supposed to. “Local” settling is what they WERE expecting. But adding that to the “deep benchmark” settling, they came up with the inch of settling reported last Friday.
**AS-IT-HAPPENED COVERAGE CONTINUES AFTER THE JUMP** Click to read the rest of As-it-happened: City Council briefed on Alaskan Way Viaduct settling…
Alaskan Way Viaduct ‘settling’ update: Tunnel contractor ‘will stop excavating’ after what today’s surveying revealedDecember 7, 2014 at 7:59 pm | In Alaskan Way Viaduct, West Seattle news | 41 Comments
(Added: Screengrab from ‘access pit’ camera – see newest image here)
7:59 PM: After today’s early-morning surveying of the Alaskan Way Viaduct, following Friday’s disclosure of a new inch-plus of “settling,” WSDOT has just published an update. While continuing to say that it’s safe to use The Viaduct, WSDOT says its contractor plans to stop the “dewatering” that was under way in the pit being dug to get to the tunneling machine:
WSDOT and Seattle Tunnel Partners conducted additional survey work early Sunday morning to further assess the amount and extent of settlement that recently occurred on and near the Alaskan Way Viaduct.
Some of the data was inconclusive and analysis is still underway; however, WSDOT observed that a small amount of differential settlement is occurring near the access pit. Differential settlement is when the ground settles unevenly over an area. When the ground settles evenly or uniformly over an area, there is less risk of damage.
The additional survey work did not find that the differential settlement has caused any new damage to the viaduct nor have we observed any damage to buildings or utilities in the surrounding area. On-the-ground surveys will continue this week by historic architects and structural engineers.
Public safety is our top priority and while we have not seen any damage, Seattle Tunnel Partners is taking the prudent step to stop dewatering. The contractor will work with its geostructural designer to stop the dewatering in a deliberate manner in order to ensure worker safety and the structural integrity of the access pit and surrounding structures.
Data analysis, collection and monitoring will continue and we will provide updates as we have new information to share.
“Dewatering” was being done as part of the access-pit excavation; as Mike Lindblom reported at SeattleTimes.com (WSB partner) after Friday’s report of settling, “Within the pit, water must be removed so that excavation machines sit on stable ground and aren’t scooping out an endless slurry.” The question now: Can digging continue without it? Yesterday marked exactly one year since the tunneling machine’s work stopped, after 1,000 feet of northward digging. WSDOT promises more information once it’s available, and we’re likely to hear more when the City Council’s prescheduled Alaskan Way Viaduct committee meets around 2:30 tomorrow afternoon.
ADDED 9:31 PM: We asked Viaduct project spokesperson Laura Newborn, who sent the above update, if this means no more digging, for now. She confirms to WSB that the contractor “will stop excavating.”
ADDED 11:11 AM MONDAY: This morning, spokesperson Newborn says that means excavation stops if/when dewatering stops, but she doesn’t have information right now on whether that’s happened yet.
First we got a text saying that protesters downtown were blocking the Seneca offramp from the Alaskan Way Viaduct; minutes later, a tweet suggested the protest was wrapping up, but now Seattle Police just tweeted:
Protesters at 1 AV/Battery St. have begun throwing rocks at officers. One under arrest. Ramps to the viaduct will be blocked in the area.
— Seattle Police Dept. (@SeattlePD) December 6, 2014
No word how long this might last, but if you’re downtown trying to get to The Viaduct or vice versa, now you know.
P.S. Just a reminder that a *scheduled* closure of Highway 99, both ways, is still on for late tonight/early tomorrow morning, 11:59 pm-5 am.
(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.”
Update on the five-hour closure planned for the Alaskan Way Viaduct this weekend - WSDOT says it will close in both directions, not just southbound as originally announced. The time frame is the same, 11:59 pm Saturday night until about 5 am Sunday morning, closed between the West Seattle Bridge and the Battery Street Tunnel. WSDOT says the closure “will allow crews to move heavy equipment across the roadway and conduct survey work.”
(From the slide deck shown at Tuesday’s stakeholders meeting)
By Tracy Record
West Seattle Blog editor
While the Highway 99 contractor Seattle Tunnel Partners hopes to make its goal of opening the tunnel by the end of 2016, the state’s point person for the project says that might be “tough.”
To say the least.
WSDOT’s Matt Preedy briefed the Alaskan Way Viaduct Replacement Project Stakeholders’ Advisory Group on Tuesday afternoon, during their every-quarter-or-so meeting at Safeco Field. He talked about what STP is doing while it’s not tunneling, and where the work toward fixing the tunneling machine is now.
The ring of pilings around the “access pit” is done, he said, and the dewatering system is on – the blue lines are wells:
The recently restarted excavation is now halfway down, about 70 feet. Once it’s done, a “concrete cradle” will be put in, and the tunneling machine will rest atop it after advancing about 20 feet under its own power. Then the big job to lift a 2,000-ton piece of the machine will begin.
The red mobile “lift tower” to bring it up is under construction now, Preedy said, pointing out that when it’s done, it will protrude a few feet above the top of the Viaduct, just a few feet from the elevated highway – “it will be an interesting visual impact for drivers on the Viaduct.”
Components have been brought in “from throughout the globe” to put together the lifting mechanism. But even once the piece is out, that’s just the start…
Quick note looking ahead to next weekend, as this one concludes: The southbound Alaskan Way Viaduct is scheduled to be closed overnight next Saturday night, from 11:59 pm December 6th until about 5 am December 7th, according to the newest “construction lookahead.” The reason for the closure between the Battery Street Tunnel and the West Seattle Bridge is described as “… crews remov(ing) a crane from the adjacent job site.”
9:31 PM: This might not last too long but in case you got stuck in the backup or have seen it – a crash on the northbound Alaskan Way Viaduct is requiring a debris cleanup, and traffic is temporarily stopped because of it (live cam here). That includes police blocking the ramp to northbound 99 from the West Seattle Bridge. So if you have to head toward downtown – take note.
9:41 PM: Just got info from Seattle Police via Twitter:
The viaduct is closed NB between WSB and Seneca St due to collision. Road is estimated to be closed for an hour.
— Seattle Police Dept. (@SeattlePD) November 19, 2014
We’re adding the live camera as an image atop this report, so you can see firsthand when it clears.
10 PM: Per scanner, police were trying to figure out how to get cars off 99. In the meantime, they also say a street sweeper will arrive in 10 minutes or so.
10:45 PM: Now open again.
2:40 PM: A week and a half after the discovery of shells stopped excavation at the Alaskan Way Viaduct-side pit where the tunneling machine’s damaged cutter head will be pulled out, the digging has resumed. So announced WSDOT this afternoon, saying archaeologists gave the tunnel contractor clearance on Sunday to get going again. According to the announcement, they “believe the shell deposits are the product of commercial shellfish activities carried out by early Seattleites around the turn of the 20th century.” Therefore, they weren’t believed to be “culturally or historically significant,” and work was allowed to resume.
3:37 PM: Any further delay for the timeline? we asked WSDOT spokesperson Laura Newborn. Her reply: “STP has not given WSDOT an updated timeline. As recently as last month, STP said it expected it would get the front end of the machine up and out of the ground sometime in December, and that it still expected repairs to be finished by the end of March.”
All contents copyright 2005-2015, A Drink of Water and a Story Interactive. Here's how to contact us.
Header image by Nick Adams. ABSOLUTELY NO WSB PHOTO REUSE WITHOUT SITE OWNERS' PERMISSION.
Entries and comments feeds. ^Top^