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 | 19 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.”
As reported here just three days ago, WSDOT announced digging had begun for the pit going down 120 feet to rescue the Highway 99 tunnel-machine cutter head. Tonight, WSDOT has announced the digging is on hold. Here’s the entire update:
On Oct. 23, WSDOT archaeologists monitoring the access pit excavation observed a deposit containing shell material that requires further evaluation and may indicate the presence of cultural materials. No artifacts or human remains were found. WSDOT has very strict protocols when archeological material is discovered and those protocols were followed today. Excavation activities in the access pit have stopped and we are now coordinating with the Federal Highway Administration and tribal governments, and the Washington State Department of Archeology and Historic Preservation to determine the next steps. As more information is available to share with the public, we will pass it along.
The image above is a screengrab from the project’s monitoring cameras, which are online “live” here.
8:47 AM: We’ve confirmed by phone with a WSDOT spokesperson that the Alaskan Way Viaduct inspection work ended early, so they will NOT be closing Highway 99 between the West Seattle Bridge and Battery Street Tunnel again today after all. The closure from the tunnel north to Valley St. IS continuing, though, so if you’re using the NB Viaduct, you’ll have to exit at Western Avenue (if not sooner).
SUNDAY NIGHT NOTE: The northern closure ended early, too, so Highway 99 is fully open both ways.
Two days after our first report that the next Highway 99/Alaskan Way Viaduct inspection closures are happening next weekend, WSDOT has new details today. Here’s the schedule:
First, a section of 99 on the NORTH end of downtown will be closed all next weekend:
·10 p.m. Friday, Oct. 17 through 5 a.m. Monday, Oct. 20: SR 99 will be closed between the Battery Street Tunnel and Valley Street for utility and paving work.
Then, it’s the previously announced closure between the West Seattle Bridge and the BSTunnel, daytime only, both days next weekend:
·6 a.m. to 6 p.m., Saturday, Oct. 18 and Sunday, Oct. 19: The SR 99 closure will be extended south to Spokane Street to allow WSDOT bridge inspectors to conduct their semiannual inspection of the viaduct. Preliminary inspection results will be released once they are available.
Two other notes:
*8 am-noon Saturday morning (October 18th) the closure will stretch to North 39th St. for a fundraising walk.
*And while all this is happening on Highway 99 – the 520 Bridge will be closed too (11 pm Friday night, Oct. 17th, until 5 am Monday, Oct. 20), which means I-5 and I-90 will be extra busy.
As always, traffic updates are a priority here, given the peninsula’s transportation challenges, so we’ll have extra weekend coverage during the closures.
NEW, 5:09 PM: Since we already have a traffic note atop the page, we’re adding this: If you use the First Avenue South Bridge, beware – a rollover crash is reported south of the bridge, in the southbound lanes. Only one lane reported blocked for starters, but that was before the major emergency response headed that way. (added) One person was in the vehicle, and is reported to be inhurt.
EARLIER TRAFFIC NOTE, 4:39 PM: Update from the road-work plan mentioned in this morning’s traffic watch: Because of the rain, WSDOT has canceled its plan to fully close northbound Highway 99 between the bridge and the stadiums overnight tonight. (You might still encounter lane closures, though.)
(EDITOR’S NOTE: Even if you agree with the advocacy group that has declared the Highway 99 tunnel a “boondoggle,” nine months after its boring machine stalled, you might be interested in a look at what’s already been done and what’s continuing to progress even before the upcoming repairs. WSDOT invited media to tour the site Thursday, and photojournalist Christopher Boffoli went on behalf of WSB. Here are his photos and narrative of how it went.
Photos, video, and story by Christopher Boffoli
Reporting for West Seattle Blog
The meeting point for our tour was an entrance at the end of South King Street just under the Alaskan Way Viaduct. After being issued safety clothes (hard hat, safety glasses, gloves, and reflective vests) we were greeted by Chris Dixon, Project Manager for Seattle Tunnel Partners, who led our group of about 7 or 8 journalists over to one of the engineering and orientation trailers.
This was a small meeting room with a lot of colorful schematics and cross-section geologic diagrams on the walls:
Dixon explained that – while the Tunnel Boring Machine (TBM) is idle – work is advancing at both the north end of the site (where a cut and cover tunnel is being prepared in the area where the TBM will eventually emerge) and the south end of the site, near the stadiums, where the future roadways are being prepared.
There is also a great deal of activity inside the existing tunnel itself. On a whiteboard Dixon drew a cross-section of the tunnel and explained how crews are busy installing structures called corbels along the tunnel floor:
These concrete structures are essentially footings that will bear the weight of the straight interior tunnel walls and the concrete road decks (southbound traffic above and northbound traffic below) that vehicles will drive over.
He said that by the time the TBM resumes its digging, they expect to have 450 feet of the tunnel’s interior complete. Dixon said that this work was originally set to happen later but that they have reconfigured the schedule while work is underway to repair the TBM.
We were joined by Matt Preedy, Deputy Program Administrator, WSDOT (and a West Seattle resident).
All of the journalists were issued numbered brass tags which were recorded on a ledger and that we pinned to our vests. As we left the engineering trailer and entered the site, there were a number of large boards with numbered dots painted on them. Dixon and Preedy went to the boards and attached their own brass tags to them.
They didn’t take the time to explain, but those ‘pit tags’ (also called check tags) are a system employed for hundreds of years to keep track of who is working inside a mine, or in this case, a tunnel. One of the first things we saw (at ground level) were piles of curved, pre-cast concrete panels that are arranged in place behind the TBM.
Bolted together into rings, they form the very strong, outer tunnel walls. Their tight-fitting gaskets are designed to keep ground water at bay.
There are ten panels in each ring and there are to be 1,450 rings in the complete tunnel.
We walked out over a concrete gantry from which we could look down on the launch pit below. To the south were the almost completed roadways that someday would carry traffic in and out of the SR-99 tunnel:
Turning around, we could see the entirety of the launch pit and the tunnel entrance at the end of it.
We descended about eight flights of steep, metal stairs to the floor of the site.
Behind us (to the south) was a completed section of cut-and-cover tunnel, with its neat, square walls, unlike the circular structure of the bored tunnel that we were about to tour.
Construction material (mostly rebar) was everywhere:
Along the sides of the pit, workers were busy covering the walls with Spray-Crete, a light, liquid form of cement.
To our right we could see the below-ground part of what we were told would become the South Operation Building. Water also seemed to be ubiquitous, seeping in all over the walls of the site.
Dixon said that, though some of it might be from nearby Elliott Bay, most of it was fresh groundwater.
We descended a ladder to an even lower section of the launch pit, level with the bottom of the tunnel.
Walking inside the tunnel at last, we could see large red concrete forms and workers installing structural re-bar along the bottom sides of the tunnel.
This is the corbel work we were told about.
Beyond the equipment and activity near the entrance of the tunnel, it was only when you walked a bit further into the tunnel that could you appreciate the impressive size of the space.
It was here that you could also appreciate the intricate puzzle of curved concrete panels.
Overhead was a large yellow ventilation shaft that brings fresh air into the deepest part of the tunnel and that can be reversed in an emergency to pull smoke from a fire out of the tunnel. Also above was part of the long conveyor belt on which tailings and slurry are removed to awaiting barges. Dixon explained that, as the TBM advances, sections of conveyor belt are added.
By the end of the project, the belt will be as long as the tunnel itself.
Outside in the open pit we had seen piles of coiled belt sections waiting to be installed in the future.
The first part of the TBM you see is the white-painted, rear superstructure of the
300 foot long trailing section.
Massive wheels support the entire machine, which includes all of the systems of wires and pipes for power and to pump chemicals and grout towards the face of the TBM. As you move forward, you encounter the system that receives the curved panel sections, picks them up, orients them to the proper position and location for installation when they are needed.
Moving forward still, you approach the section of the TBM that is behind the cutting face.
Everything there seems covered with some form of water or mud. There are hazards to footing and low clearances, making it a challenge to decide if you should watch your head or where you step. Everything was lit with fluorescent tubes, giving it a bright – if slightly green – cast. As we arrived to the most recently-installed ring of curved concrete sections, at the very bottom, Dixon and Preedy showed us the enormous pistons that the TBM uses to push against the edge of the course of concrete rings to advance itself forward.
As politicized as the bored tunnel has been and continues to be in Seattle, I must say that standing in the bowels of the machine, it is difficult not to be in awe of the scale and size of the complex machinery, the intricate tapestry of conduits, hoses, pistons, motors, fittings and beams – the sheer audacity of the technology involved in pushing through the earth blindly at 100 feet below sea level.
It is a level of technological complexity that I have only before seen when watching a Ridley Scott film set inside of a spaceship. It did not seem like a place that a group of human beings should be standing. And it was even more incomprehensible that people had designed and built it.
We climbed narrow staircases through a maze of passageways to see where the muddy tailings from the cutting face begin their journey out of the tunnel.
On another level we visited the control room with the screens and consoles from which workers can manage and monitor all aspects of the TBM when it is in operation.
Dixon explained that the numbers we saw on the primary displays indicated just over two bars of pressure (regular atmospheric pressure is one bar; most commercial espresso makers operate at 10-15 bars of pressure). Even though the TBM was not running he said that the instruments generally don’t read much more than that. He added that – when in operation – the cutting face of the TBM isn’t even all that loud, though Preedy added that all of the motors that power the conveyor belts for the removal of tailings do make the back of the machine very noisy.
Though the TBM was idle, Dixon said that workers are kept busy “exercising” and maintaining many of the parts of the machine that might atrophy or otherwise fall into disrepair if left sitting for a long time. It wasn’t uncomfortably warm inside the heart of the machine, though Dixon said that when the TBM is in operation it does get quite hot down there as the heat of friction is transferred through the cutting face to the surrounding spaces. Heat played into what went wrong, and what’s being fixed, he explained:
Adjacent to the control room – still inside the heart of the TBM structure – was a break room that, with coffee maker, microwave oven, long lunch tables, etc. would look at home in any factory. It was hard to believe it was at the center of an incredibly complex machine deep underground.
Nearby we saw a collection of cutting heads, each weighing 1500 pounds, that could be attached to an overhead rail for transport to the front of the cutting face for replacement. Various cutting heads are used, depending on the soil conditions.
The “rippers” we saw are best suited for the type of loose glacial soils that are expected in this section of the project.
At the very front of the TBM we could see the large blue motors that individually power each of the cutting heads.
On the same level we could see the central drive shaft, painted light green. And to the sides were large pressure vessels through which men and equipment could safely transition to the pressurized area on the other side of the cutting face, if needed.
With our tour complete we walked back through the various stairways and passages, back down to the tunnel floor at the rear of the TBM’s trailing gear, and out the way we came.
The palms of my light-colored gloves – which had honestly seemed like overkill at the start of the tour – had somehow become darkened.
After we had climbed the fairly treacherous ladders and countless treads of metal stairways, we were led back to the engineering and orientation trailers where, one by one, we turned in our numbered brass tags and were signed out of the ledger.
What happens next in the repair process? Here’s the latest update on the project website. For more on the project’s status, here’s what our partners at The Seattle Times published post-tour.
Just in case you’re not sure: The Alaskan Way Viaduct will be open tomorrow. Highway 99 north of there won’t.August 24, 2014 at 9:49 pm | In Alaskan Way Viaduct, West Seattle news | 6 Comments
With some simply describing the Highway 99 work as a “4-day closure,” here’s a reminder: For the part most used by West Seattleites, it’s not. The Alaskan Way Viaduct WILL reopen by 5 am Monday, WSDOT says (as will 99 between the AWV and West Seattle Bridge). What will NOT be open (yet) is Highway 99 north of The Viaduct – from the Battery St. Tunnel north to Valley Street on Lower Queen Anne, as shown here:
That section is supposed to remain closed for bridge work until early Wednesday. Though The Viaduct will be open again, it’s still wise to avoid it if you can, since anyone still on 99 past Seneca will have to exit at Western, and that’s likely to back things up. South of there, state crews spent the weekend closure replacing concrete panels; WSDOT’s latest update says, “The final concrete has been poured on these new panels and will cure overnight. Drivers should experience a smoother ride in SODO during Monday morning’s commute.” We’ll be monitoring morning traffic here as usual, with live cameras in our daily update as well as on the WSB Traffic page.
Before we get to this weekend’s big Highway 99/Alaskan Way Viaduct closure (which continues north of the Viaduct for two days beyond that, WSDOT has announced some nighttime lane closures this week for prep work, starting tonight. Here’s the alert:
Drivers who use State Route 99 through Seattle’s SODO district should plan ahead for possible nighttime delays this week.
Contractor crews working for the Washington State Department of Transportation will close up to two lanes in both directions between Spokane and Atlantic streets nightly for pavement rehabilitation work.
The southbound lanes will begin closing at 9 p.m., and the northbound lanes will begin closing at 10 p.m. All lanes will be open by 5 a.m.
In addition to the weeknight closures, the eastbound West Seattle Bridge off-ramp to northbound SR 99 will close from 10 p.m. Thursday, Aug. 21 until 5 a.m. Friday, Aug. 22.
The work will help prepare the roadway for the upcoming weekend closure of SR 99 in which 81 damaged concrete panels will either be repaired or replaced. The $10.08 million project on the south end of the Alaskan Way Viaduct will extend the life of SR 99 and provide a smoother, safer ride for drivers.
While everything is status quo with the Alaskan Way Viaduct/Highway 99 north of the West Seattle Bridge THIS weekend, WSDOT reminds you that won’t be case by this time NEXT weekend. The map above shows the planned closure – for various reasons you can read about here – starting 10 pm next Friday night, August 22, with the exception of two access points for traffic exiting the Seahawks game until midnight. By Monday morning, August 25th, the WS Bridge-to-Battery St. Tunnel section should reopen, but the tunnel-to-Valley St. section will stay closed two more days:
Again, that all starts NEXT Friday night. And we’ll be reminding you daily in our regular WSB traffic coverage between now and then.
In June, we reported on WSDOT’s plan to close part of Highway 99 (including the Alaskan Way Viaduct) in late August for repair work. Today, new details are out – see them here – since WSDOT has locked in more details. Key points: 99 will be closed both ways from the West Seattle Bridge to Valley Street from late Friday night, August 22nd, until early Monday morning, August 25th; the section from the WS Bridge to the Battery Street Tunnel will reopen then, but the stretch north to Valley will remain closed until Wednesday, August 27th.
P.S. If you have questions about ongoing Highway 99 work, including (or not) the tunnel, WSDOT has a booth here at West Seattle Summer Fest, all weekend long.
ORIGINAL TUESDAY REPORT: New information today about a full Alaskan Way Viaduct closure coming up later this summer. It was mentioned – without a date – when WSDOT‘s Secretary Lynn Peterson and Todd Trepanier spoke to the West Seattle Transportation Coalition earlier this month (WSB coverage here); Trepanier talked about keeping The Viaduct in good shape for its remaining years of usage, and noted a repair closure was ahead. Then this past weekend, chatting at the Morgan Junction Community Festival, Pete Spalding, a West Seattleite on the “stakeholders’ group” that WSDOT convenes quarterly, told us the group had just been given a specific date. We have now confirmed it via WSDOT spokesperson Laura Newborn:
WSDOT will be replacing or repairing 81 concrete panels on SR 99 between Forest and Holgate during the weekend of August 23. These panels are aging and as a result are cracked, potholed, and some have failed and need to be completely replaced.
The panel work and additional work needed on the North Access portion of the tunnel project will require a closure of SR 99 in both directions from the West Seattle Bridge to Valley Street, just north of the Battery Street Tunnel. We will have more specific details when the work plan is finalized, but your readers should note that SR 99 will be closed from the bridge to the tunnel on the weekend of August 23.
That day is a Saturday; the yet-to-come details, of course, will include specific start and end times. More details about the repair project are here.
ADDED WEDNESDAY MORNING: As a postscript, an update from WSDOT with a few more details, including plans for the north portion of the closure to extend past the weekend:
WSDOT will be replacing concrete panels on SR 99 in SODO and rebuilding SR 99 where it crosses Broad Street north of the Battery Street Tunnel. To complete this work, crews will close SR 99 in both directions between South Spokane Street and Valley Street the weekend of Aug. 23 and 24. Work on SR 99 north of the Battery Street Tunnel will continue on Monday and Tuesday, Aug. 25 and 26. We are still finalizing the timing and location of this closure and will share information with the public as soon as we have it.
4:03 PM: Thanks to West Seattle Hipster for the tip – confirmed via WSDOT tweet – Northbound 99/Alaskan Way Viaduct has reopened between here and the Western Avenue offramp. But it’s still closed from Battery St. to Valley St., so if you’re heading beyond Belltown (etc.), you’ll still have to detour.
7:08 PM: 99 is fully open, says WSDOT.
Just last week at the West Seattle Transportation Coalition‘s monthly meeting (WSB coverage here), top WSDOT executives answered a few questions about the stalled tunnel machine and its pending repairs. Today, the contractor, Seattle Tunnel Partners, is out with its official repair plan, and animation (above) showing what’ll happen during its phases. According to the timeline toward the end of the plan, they’re still expecting to resume tunneling in late March of next year.
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