Alaskan Way Viaduct Replacement Program News – August 2014


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.

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.


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


Seattle City Light Increasing Electrical Capacity Along 1st Avenue


Updated Information: Seattle City Light plans to pull in new underground power lines along 1st Avenue from King Street to Washington Street on Wednesday, February 26 and then from Washington Street to Cherry Street on Wednesday, March 5. We want you to know about the work and its impacts.

What:                  Several-day job, pulling and splicing cable

Why:                    Upgrading our system to increase electrical capacity and reliability

Where:               Vaults located in parking lane on west side of First Avenue from King Street to Washington Street and from Washington Street to Cherry Street. See maps on reverse side.

When:                 Pulling cable between King Street to Washington Street is planned for Wednesday, February 26 from 6:30 p.m. to 10:30 p.m.

Pulling cable between Washington Street to Cherry Street is planned for Wednesday, March 5 from 6:30 p.m. to 10:30 p.m.


Project Impacts – What you can expect:

  • No planned outages or trenching
  • City Light trucks on the street, crews working from vault to vault
  • Splicing cable has limited impacts to traffic and parking and will take place on side streets following the two nights of cable pulling.
  • Localized traffic, parking, and noise  impacts at the vaults where the work is occurring
  • Uniform police officers will direct traffic


No parking signs will be used for the spaces near the vaults where work is to occur. The signs will give the hours of our work and will be picked up as the work progresses if crews no longer need access to an area.  For more information about available parking in the area, please go to:


Thank you for your patience.  For any questions you may have or for more information, contact Becky Ginn, Electrical Service Representative, at 206-386-1553 or

Sidewalk closure required for Pergola repair

Closed for two days!Closure expected to last two days

The sidewalk under the Pergola in Pioneer Square will be closed on Thursday, Feb. 6, and Friday, Feb. 7, while workers repair broken glass and assess other damage to the structure.

Contractor Herzog Glass will be on site to replace the 28 glass panels that were broken or damaged after Super Bowl revelers climbed on the Pergola. During the sidewalk closure Seattle Parks and Recreation staff will make a closer inspection of the top of the structure to better understand any damage.

The cost of repairs is estimated to be between $15,000 and $25,000, which has all been donated by the community. Community members Amanda Gallagher Quinn and Shana Pennington-Baird started a crowd-funding campaign that raised more than $16,000 in less than 24 hours. The Western Washington Honda Dealers Association donated $10,000. The Seattle Parks Foundation is handling all the donations. Any money left after Pergola repairs are paid for will be used for Pioneer Square parks and green spaces.

Pioneer Square Pergola

The Pergola was commissioned for construction in 1909 to be the covering to an underground comfort station, said to be the most ornate west of the Mississippi River. When local media told the public about the $25,000 price tag, there was some community resistance. Then-Park Board Executive Ferdinand Schmitz was so certain of future popularity of the Pergola and underground restroom that he promised to repay the City in full if people objected to it. He never had to make good on his promise. The comfort station closed in the 1940s.

On Jan. 15, 2001, the Pergola was hit by a truck, and shattered. The thousands of shards of cast iron were painstakingly pieced together by the century-old, family owned Seidelhuber Iron & Bronze Works in South Park. The refurbished Pergola is now supported by an internal skeleton of 20 tons of structural steel.

The Pergola and the Tlingit Totem Pole in Pioneer Square Park, as well as the adjacent Pioneer Building are all National Historic Landmarks.

Alaskan Way Viaduct Replacement Project Update – February 2014

BerthaIt’s been a busy start to 2014 with the opening of the South Atlantic Street overpass and crews working to get Bertha, the SR 99 tunneling machine, digging again.  Here’s a recap of what we’ve been up to:

Milepost 31 Speaker Series: Learn about the South Atlantic Street overpass
On Monday, Jan. 27, we opened a new overpass to the west of Seattle’s stadiums, just south of Pioneer Square. The overpass allows traffic to bypass a busy railroad track that crosses South Atlantic Street. Before the overpass, train activity often blocked traffic for extended periods, which not only slowed truckers traveling to and from the Port of Seattle, but also created backups that stretched onto Seattle streets and Interstate 90. The overpass saves truckers as much as 20 minutes of travel time between the port and I-5 or I-90.

Visit Milepost 31 between 6 and 6:30 p.m. on Thursday, Feb. 6 to talk to staff about how the structure is changing traffic patterns in the area. Read more about the overpass here.

Further evaluation required before tunneling can resume
On Tuesday, Jan. 28, Seattle Tunnel Partners (STP) pushed the SR 99 tunneling machine – which had been stopped since Dec. 6 – forward approximately 2 feet. Moving the machine forward allowed crews to further test the functionality of the machine and determine if they could resume full-production mining. It also created sufficient space to build the next concrete tunnel liner ring on Wednesday, Jan. 29.

When the machine moved forward, crews saw indications of above-normal temperature readings in part of the machinery, similar to readings encountered before crews initially decided to stop mining on Dec. 6. On Wednesday, STP made adjustments and mined an additional 2 feet. The above-normal temperatures persisted, and STP made the decision to stop and perform further evaluations.

STP crews and tunnel engineers are operating the world’s largest tunneling machine in complex conditions. Although their investigations to date have provided a great deal of information, we will not be able to definitively identify the issue or issues facing the machine until tunneling experts complete their review. We will provide additional information as it becomes available.

Please visit our webpage for regular updates.