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SR 99 tunnel crews successfully mined beneath the Battery Street Tunnel this week. The top of Bertha, the SR 99 tunneling machine, passed approximately 90 feet below the bottom of the 62-year old tunnel, which will permanently close when highway traffic shifts from the Alaskan Way Viaduct to the new tunnel.The ground along the tunnel route remains stable as Bertha pushes toward the finish line near Seattle Center. Crews are now less than 1,600 feet from the end of the tunnel drive, and the machine is climbing at a steady rate. The distance between the top of the machine and the surface is approximately 115 feet. The tunnel, at its deepest point, is approximately 215 feet deep.Up next for Bertha: a trip beneath Fifth Avenue and the Seattle Center Monorail. The top of the machine will pass approximately 90 feet below the Monorail’s supports.Highway constructionWhile crews inside the tunneling machine are focused on mining, separate crews are hard at work building the double-deck highway inside the tunnel. The new roadway now stretches more than 3,800 feet into the tunnel, near the southern edge of Pike Place Market.Work has also begun on the mechanical, electrical and plumbing systems within the tunnel. Crews began installing these systems near the stadiums last week and will continue to progress north, even after the tunnel drive is complete.Progress updates are posted on Mondays and Thursdays at our Follow Bertha page. You can also follow Bertha on Twitter @BerthaDigsSR99.— more —
Seattle Tunnel Partners resumed mining late Monday following 10 days of hyperbaric maintenance on Bertha, the SR 99 tunneling machine.Crews replaced approximately 300 of the nearly 500 scrapers on Bertha’s cutterhead during the hyperbaric maintenance period. As this post explains in more detail, the scrapers line the sides of the cutterhead spokes. STP also conducted other important inspections and maintenance during this time.Completing routine maintenance is an important part of ensuring that the machine continues to operate properly. STP will continue to perform inspections and maintenance as needed over the remainder of the tunnel drive.Crews are less than 2,500 feet from the receiving pit near Seattle Center where Bertha will emerge at the end of tunneling. The top of the cutterhead is located approximately 160 feet below Third Avenue in Belltown.Progress updates are posted on Mondays and Thursdays at our Follow Bertha page. You can also follow Bertha on Twitter @BerthaDigsSR99.— more —
Seattle Tunnel Partners is making good progress as they continue performing hyperbaric maintenance on Bertha, the SR 99 tunneling machine. Since the maintenance period began on Jan. 5, crews have replaced 250 cutterhead tools (see example below) over the course of 184 hours of hyperbaric shifts. This maintenance is critical as STP prepares for the final 25 percent of the tunnel drive.The work is taking place in the chamber behind Bertha’s cutterhead, as shown in this image (PDF). As the video below explains, working in this environment is similar to performing an underwater dive.STP will resume tunneling when the maintenance period is complete. The top of Bertha’s cutterhead is located approximately 160 feet below Third Avenue, about halfway between Blanchard and Bell streets. Crews are less than 2,500 feet from the receiving pit near Seattle Center where Bertha will emerge.— more —
Just a few days before the SR 99 tunneling machine started tunneling under the Alaskan Way Viaduct, the Washington State Department of Transportation flew a video-equipped drone through the SR 99 tunnel to show Seattle Tunnel Partners’ construction progress. There has been continued interest in seeing what has been built below ground and this video gives a glimpse of the tunnel as well as the nooks and crannies of the complex tunneling machine.
On an average day, the tunnel is … more
This week, at the south entrance to the bored tunnel, Seattle Tunnel Partners is pouring concrete for a section of the future southbound highway. On one hand, the pouring of concrete (also known as a "concrete placement”) is nothing extraordinary – it’s a common occurrence on a project that will use enough concrete to build nine football stadiums. But their frequency belies the complex choreography that goes into executing each pour successfully. Since concrete plays … more
Keeping the public informed about our work to replace the Alaskan Way Viaduct is an important part of what we do every day. Our goal is to give you as much access as possible to this amazing project, which is why we regularly post updates, photos and videos of our progress. We even offer walking tours from our information center, Milepost 31, to a viewing platform that overlooks the pit where tunneling began in summer 2013.
Unfortunately, there’s one frequently received request … more
As reported elsewhere on our website, work to access and repair the SR 99 tunneling machine is coming along. We’ve heard from some people that Seattle Tunnel Partners’ repair plan is hard to picture. Enter STP’s Chris Dixon, who was nice enough to narrate a video that explains what crews are doing to resume tunneling by March 2015. Watch it on YouTube or download a WMV file.
Seattle Tunnel Partners repair work plan (pdf 4.8 Mb) … more
We’ve been asking you to do your part to reduce congestion when SR 99 closes for four days starting Friday night, Aug. 22. That includes things like changing your commute habits and choosing an alternate way to get around.
But what are we, the agencies tasked with keeping traffic moving during this closure, doing to help? Quite a bit, actually. Here’s a roundup of some of the steps we’re taking to help you and your fellow commuters through the closure.
Washington … more
Less than three years ago, crews demolished the southern mile of the Alaskan Way Viaduct. When they did, they shifted traffic onto a new section of State Route 99 south of downtown Seattle.
Much of that new section of SR 99 is permanent, but the piece west of the stadiums is temporary. This curving stretch of road takes drivers around the SR 99 tunnel construction site and connects to the remaining section of the viaduct near South King Street. It’s nothing fancy, but it’s … more
Just in time for Bike Month, we opened a new permanent connection between the on-street bike lanes south of South Atlantic Street and the shared-use path from South King Street. Here’s a map that shows the improvements, which include:
A dedicated, 14-foot-wide shared-use path with improved paving.
A separate northbound and southbound path for more efficient navigation.
Signs warning of vehicles crossing the intersection of … more