Bertha expected to temporarily close Alaskan Way Viaduct in early 2016
Dec 30, 2015, 11:30 PM | Updated: May 7, 2016, 11:31 pm
Bertha bored about 8 feet before crews operating it went on vacation.
Seattle Tunnel Partners plans to continue tunneling after the weekend, and the Washington State Department of Transportation is giving drivers a heads up about one major upcoming closure.
Crews plan to do prep work and mine out of the 120-foot access pit toward a future maintenance stop (about 450 feet north). That work is scheduled to begin Jan. 4 or 5. Along the way, crews will mine slowly while installing tunnel rings and continuing to run tests.
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Tunneling under the viaduct will require a full closure of SR 99 through downtown for approximately two weeks. The contractor’s latest projections show that the closure will occur in March, but the actual closure date will depend on Bertha’s progress.
According to the Washington State Department of Transportation: “WSDOT recognizes that closing a major highway will have regional traffic impacts. This is a necessary and planned step toward completing a project that will transform the city and region … This temporary closure of the viaduct is precautionary. Removing vehicles from the structure will allow crews to better monitor the viaduct while Bertha mines underneath, and quickly address any movement that might occur.”
When Bertha reaches the future maintenance stop — essentially an underground block of concrete just south of Colman Dock — crews will perform maintenance and make final adjustments before diving beneath the viaduct.
It takes 10 segments to build a tunnel ring and a total of 1,450 rings to create the outer wall of the SR 99 tunnel. You can watch a tunnel ring being built here.
