SR 99 tunnel crews have now bored 8,132 feet of the 9,270-foot SR 99 tunnel. The top of the machine’s cutterhead is located north of Wall Street, near Sixth Avenue North, approximately 100 feet below the surface.Crews successfully mined past the Seattle Center Monorail late last week. From their current location, crews will continue to mine north past the intersection of Denny Way and Sixth. The machine will emerge in a pit two blocks north of Denny, at the intersection of Thomas Street and Sixth.Progress updates are posted on Mondays and Thursdays at our Follow Bertha page. You can also follow Bertha on Twitter @BerthaDigsSR99.Balloons mark Bertha's location near Sixth Avenue Northand Wall Street on Feb. 23.— more —
The Hot Chocolate Run and additional road work will also extend the closure north of the Battery Street TunnelIt’s almost March and that means it’s time for a weekend-long inspection of the State Route 99 Alaskan Way Viaduct. Every March and October, the Washington State Department of Transportation closes SR 99 through Seattle so engineers can conduct a thorough inspection and make sure the viaduct remains safe for everyday driving.On Saturday, March 4 and Sunday, March 5, the viaduct will close in both directions. The northbound road will close between South Spokane Street and the north end of the Battery Street Tunnel. The southbound roadway closure will extend further north to Valley Street in South Lake Union so construction crews can complete the work needed to reopen Harrison Street.On Sunday, March 5, the annual Hot Chocolate Run will also extend the closure north of the Battery Street Tunnel.Drivers through Seattle should plan ahead and be prepared for additional congestion. The Seattle Department of Transportation will post updated information on their traveler information webpage.Additionally, drivers can check WSDOT’s travel tools for information about traffic in the Puget Sound region.Closure Details6 a.m. to 6 p.m. Saturday, March 4, and Sunday, March 5
Sunday, March 5
- Alaskan Way Viaduct closed for its scheduled inspection between South Spokane Street and the north end of the Battery Street Tunnel.
- On Saturday, March 4, the closure of the southbound roadway will extend north to Valley Street in South Lake Union for work to restripe Harrison Street.
- The Hot Chocolate Run will close SR/99 Aurora Avenue North in both directions north of the Battery Street Tunnel.
- The northbound lane closure will extend to North 45th Street from 6:15 a.m. to 11:15 a.m.
- Southbound SR 99/Aurora Avenue North will be closed north of the Battery Street Tunnel to North 38th Street from 6:15 a.m. to 11:00 a.m.
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- In addition, the northbound lanes of the Battery Street Tunnel will remain closed until approximately 1 p.m. for a Project Belltown walk through the Battery Street Tunnel.
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 —
Clean air is a critical element of a safe and well-functioning tunnel. In the new SR 99 tunnel, a complex system of fans will push and pull air into and out of the tunnel to ensure fresh air during routine operations and in emergencies.
The first element of the tunnel’s ventilation system is the very traffic that uses it. Vehicles traveling through the tunnel will act like pistons, pushing fresh air into the tunnel. But when that piston effect needs a boost, the tunnel will turn to … more