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 Project Update – April 2014

Milepost 31 Events

April 19, 2014 events at Milepost 31First Thursday Speaker Series – Bertha and Progress on the SR 99 Tunnel Project

April 3, 2014
6 – 6:30 p.m.

You’ve been hearing a lot lately about our efforts to replace the State Route 99 Alaskan Way Viaduct. This is a big, complex undertaking. And as we all know, we’ve encountered some challenges. Join us this Thursday at Milepost 31 as speakers from WSDOT and our tunnel contractor, Seattle Tunnel Partners (STP), explain what’s being done to address these challenges and get Bertha, the SR 99 tunneling machine, moving again.

Speakers:

  • Matt Preedy, WSDOT’s deputy administrator for the Alaskan Way Viaduct Replacement Program
  • Chris Dixon, Seattle Tunnel Partners (STP) project manager

History Scavenger Hunt

April 19, 2014
1 – 4 p.m.

Join us at Milepost 31 for our monthly activity for kids. This month we’re hosting a scavenger hunt eggstravaganza  (pdf 371 kb) to discover Pioneer Square’s rich transportation history. Hop on down with your family and friends to explore historic icons and hidden gems in Seattle’s oldest neighborhood. Test your knowledge, check out cool new Pioneer Square locales, and enter to win a grand prize furnished by the Alliance for Pioneer Square. Pick up your scavenger hunt kit at Milepost 31 between the hours of 1 and 4 p.m.

And don’t forget you can find regular updates about Bertha on Twitter by following @BerthaDigsSR99.

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

BerthaYou’ve been hearing a lot lately about WSDOT’s efforts to replace the State Route 99 Alaskan Way Viaduct (AWV). This is a big, complex undertaking. And as we all know, we’ve encountered some challenges. Join Matt Preedy, AWV Deputy Program Administrator, as he explains how WSDOT and STP are addressing these challenges and what the plan is to get Bertha, the SR 99 tunneling machine, moving again.

Thursday, March 6, 2014

6 to 6:30 p.m.

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. Milepost 31 is open Tuesdays through Saturdays from 11 a.m. to 5 p.m., and stays open until 8 p.m. on First Thursdays.  Free parking is available for First Thursday art walk patrons in Pioneer Square. Please visit www.FirstThursdaySeattle.com for more information about participating garages.

And don’t forget you can find regular updates about Bertha on Twitter by following @BerthaDigsSR99.

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.