Tunnel Project Update

BerthaWSDOT and Seattle Tunnel Partners conducted additional survey work early Sunday morning (12/7/2014) 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.

Alaskan Way Viaduct Replacement Program News – August 2014

BerthaTopics:

Bertha update – Construction of the access pit’s underground walls will continue through August

Earlier this week, Seattle Tunnel Partners notified us that building the underground walls of the circular pit (pdf 2.5 Mb) crews will use to access and repair the SR 99 tunneling machine will continue through August. While this date is later than anticipated, STP reports that tunneling is still expected to resume as scheduled in March 2015.

Building a self-supporting, concrete ring that is 120 feet deep and 80 feet wide is no easy task, especially given the difficult ground conditions near South Jackson Street. STP crews have completed more than half of the underground piles and are working around-the-clock, seven days a week to complete the approximately 31 remaining piles.

There are several reasons the work is taking longer than anticipated. One factor is the addition of 11 piles to the pit’s design, bringing the total number of piles to approximately 84. Crews are also working with exceptionally large interlocking piles, which are necessary to make the pit self-supporting without tiebacks or other reinforcements. A self-supporting pit is what will allow the tunneling machine to mine through its walls, but the large piles take longer to install than standard piles.

While pile work continues, crews are making progress on other areas of the repair plan on schedule, including:

  • Shipping repair pieces: The new main bearing has arrived in Seattle and will be assembled closer to the time it’s needed, likely this fall.
  • Manufacturing repair pieces: Other repair pieces, such as the new outer seal ring, the thrust seal ring and bearing block are nearing completion. After these pieces are fabricated and inspected, Hitachi Zosen will ship them to Seattle.
  • Assembling a 300-ton crawler crane: This crane will be used to help assemble the 600-ton crawler crane. Pieces of that crane will arrive in September and assembly will begin shortly thereafter.
  • Assembling a 600-ton crawler crane: This crane will be used to assemble the modular lift tower (massive red crane) that will lift the largest pieces of the machine from the access pit. Parts of that crane will also arrive in September and assembly will begin in late September.
  • Assembling the 2,000-ton modular lift tower: Starting in late July and continuing through fall, crews will begin to stage the modular lift tower. Parts of the modular lift tower will arrive over the next several months beginning in late July.

We will continue to update you on STP’s efforts to resume tunneling by March 2015. You can watch the access pit take shape on our time-lapse camera, and view photos of recent construction on Flickr.
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Early warning – Four-day closure of SR 99 coming in late August

In late August, crews building the future north portal of the SR 99 tunnel will close SR 99/Aurora Avenue North near South Lake Union for four days. During this closure, crews will demolish and replace the section of SR 99 that crosses above Broad Street.

To minimize the need for additional closures, separate crews will complete the following work elsewhere along the SR 99 corridor during this time:

  • Utility work at Harrison Street.
  • Concrete panel replacement in SODO.
  • Expansion joint repairs on the Alaskan Way Viaduct near the Seneca Street off-ramp.
  • Ivy removal from the viaduct.

Closure information

Drivers should plan ahead for SR 99 closures from Friday night, Aug. 22 to Wednesday morning, Aug. 27. View a map of the closure.

  • From 10 p.m. Friday, Aug. 22 to 5 a.m. Monday, Aug. 25, SR 99 will be closed in both directions from the West Seattle Bridge to Valley Street.
    • Northbound SR 99 will be open from South Royal Brougham Way until midnight on Friday, Aug. 22 for exiting Seahawks traffic.
  • From 5 a.m. Monday, Aug. 25 to 5 a.m. Wednesday, Aug. 27, SR 99 will be closed in both directions from the south end of the Battery Street Tunnel to Valley Street.

Driver tips

Travelers who use SR 99 should consider the following:

  • Allow plenty of extra time and expect additional congestion on alternate routes including I-5 and surface streets.
  • Leave early or delay your trip to avoid traveling during peak commute periods in the morning and afternoon.
  • Delay or reschedule discretionary trips.
  • Consider telecommuting.
  • Choose an alternative travel mode such as King County Metro, share a ride in a car or vanpool, or walk or ride a bicycle. 

Know before you go and have a backup plan

Those who must drive are encouraged to stay engaged and check traffic conditions frequently via WSDOT’s web, mobile and phone-based traveler information systems.

  • The Seattle traffic page contains updated road information including links to traffic cameras.
  • The travel alerts website provides real-time information about blocking incidents.
  • WSDOT’s mobile app offers information for travelers on the go.
  • @wsdot_traffic provides Twitter updates about travel issues.
  • 5-1-1 offers traffic updates.
  • The What’s Happening Now page chronicles closures and issues affecting travelers.
  • Learn more about your commute and travel choices.

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Milepost 31 Speakers Series – Bertha and progress on the SR 99 Tunnel Project

Seattle Tunnel Partners, the contractor hired by WSDOT to design and build the SR 99 tunnel, is working to repair the SR 99 tunneling machine. Join us to learn more about STP’s plan to resume tunneling by the end of March 2015, and learn about the other work happening to replace the viaduct.

  • 6 – 6:30 p.m.
  • Thursday, Aug. 7
  • Milepost 31, 211 First Ave. S., Seattle
  • Admission is free

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Alaskan Way Viaduct Replacement Project Update – July 2014

BerthaContractor announces details of repair work plan for the SR 99 tunneling machine

Bertha, the SR 99 tunneling machine, has always been big. The focus now is on rebuilding Bertha and making her better, according to a new repair work plan unveiled Monday, June 16, by Seattle Tunnel Partners, our design-build contractor for the SR 99 Tunnel Project.

STP’s work plan (pdf 4.8 Mb), which is illustrated in a new animation (view on YouTube), contains four major repair and enhancement elements:

  • Replacing the damaged seal system with a more robust system
  • Replacing the main bearing
  • Installing enhanced monitoring systems
  • Adding steel to strengthen the machine and accommodate the new seal system

Other major enhancements of the work plan include:

  • Widening the openings at the center of the cutterhead
  • Improving the soil conditioning injection system
  • Installing bit- and wear-resistant steel on the cutterhead
  • Extending the length of the agitator arms in the mixing chamber

STP will provide WSDOT with additional supporting information about rebuilding the machine in the coming months, in accordance with the design-build contract, to demonstrate how the repairs will meet the contract’s performance and technical requirements, including:

  • An analysis demonstrating that the machine’s structure can withstand all loads from the surrounding ground and its own operation
  • Seal design details and background calculations
  • Design of revised conditioner injection systems and cutterhead openings
  • Updated operations plan including enhanced instrumentation and monitoring for key machine components
  • Complete testing program for all modified machine components prior to restart of mining

Bertha is currently stopped approximately 60 feet underground between South Jackson and South Main streets. As owner of the machine, STP is responsible for ensuring it functions properly at all times. STP is currently building the underground walls of a circular pit (pdf 2.5 Mb) crews will use to access and repair the machine.

 

No Milepost 31 speaker series in July

Due to the July Fourth holiday, there will be no Milepost 31 speaker series event this month. We look forward to seeing you in August.

Alaskan Way Viaduct Replacement Update – May 2013

www.FirstThursdaySeattle.comCutterheadMilepost 31 Speaker Series – Preparing for the SR 99 tunneling machine’s summer launch

After a 5,000 mile journey from Japan and 10 days of unloading, Bertha, the world’s largest-diameter tunneling machine, is officially on Seattle soil.  Join us at this month’s speaker series for a project update including a behind-the-scenes look at the machine’s arrival. We’ll also talk about what’s next for Bertha as crews assemble her 41 pieces in the launch pit and prepare for the start of tunneling this summer.

6 to 6:30 p.m.
Thursday, May 2

Milepost 31

211 First Ave. S., Seattle

Admission is free.

After the talk, be sure to leave enough time to explore the rest of the First Thursday Art Walk in Pioneer Square. Free parking is available for First Thursday art walk patrons in Pioneer Square. Please visit www.FirstThursdaySeattle.com for more information about participating garages.

What’s next for Bertha, the SR 99 tunneling machine

Now that spring is here, get outside and take a self-guided walking tour along the paved path west of the work site and watch as crews prepare to reassemble Bertha. Many of Bertha’s pieces including the cutterhead and trailing gear are visible in the work zone. Spot them now before the massive red crane begins lowering Bertha’s pieces into the launch pit. Reassembling and testing the machine will take two to three months. Bertha is scheduled to start digging this summer.

Building one road above another: the South Atlantic Street overpass

Crews continue to build the new South Atlantic Street overpass over SR 99 to the west of Seattle’s stadiums. The wooden forms you see are called falsework, which is a temporary structure that creates a mold where crews will pour concrete to build the permanent structure. Scheduled to open in late 2013, this overpass will allow traffic to bypass frequent train blockages on South Atlantic Street.

For more information about the Alaskan Way Viaduct Replacement Program, visit www.alaskanwayviaduct.org. You can also track Bertha’s progress on Twitter by following @BerthaDigsSR99.