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December 22, 2014 at 2:31 PM

Tentative Highway 99 tunnel opening: August 2017

The Highway 99 tunnel schedule will absorb another eight months of delay — not opening until August 2017, according to an a tentative schedule released Monday.

Seattle Tunnel Partners gave that estimate in an Oct. 31 schedule chart, which was released Monday by the Washington State Department of Transportation. That would increase total delays to 20 months beyond the original goal to serve traffic in the four-lane, tolled tunnel at the end of next year.

The state also announced some good news, that soil settlement in the historic Pioneer Square area is probably less than the 1.4 inches that WSDOT described last week and that no structural damage was found in examinations of 50 buildings. A few showed “cosmetic damage,” such as doors and windows sticking, an official update said.

Among other effects, more delays mean that bus riders and drivers entering Seattle on Aurora Avenue North will suffer longer through the bottleneck at Valley Street, where the state and city governments say only two general lanes each direction can be provided until tunnel machine Bertha completes its job.

As of Monday, crews along the waterfront have dug 90 feet of the 120-foot deep access vault, which will be used to lift and repair the front end of Bertha, the stuck tunnel-boring machine.  A mammoth red crane has been erected by the Mammoet company next to the Alaskan Way Viaduct, to lift the broken part to the surface.

Chris Dixon, project manager for STP, disclosed a new issue with the vault, causing excavation to halt until early January.  A few vertical pilings, designed like a wall to contain  concrete grout, have shifted out of plumb, so it’s difficult to inject “interstitial grout” between the nearby pilings.

Five pilings, shown in brown, must be replaced so that grout will fill the ring snugly.

Five pilings, shown in brown, must be replaced so that grout will fill the ring snugly. (STP image)

A tight seal is needed so that the ring-shaped vault will reinforce itself against massive soil and groundwater pressures. It’s a safety issue, as well as essential for preserving the vault, which has no internal bracing.  Five of these pilings must be removed.

 

The state DOT emphasized that it cannot provide any specific completion date, given that repairs to Bertha haven’t begun yet.  A week ago, Transportation Secretary Lynn Peterson did not mention the August 2017 opening date in a City Council hearing.

 

August 2017 would be four years after Bertha began digging at Sodo, only to halt some 1,025 feet into the 9,270-foot route from Sodo to South Lake Union.

“The one thing we can say for certain is the TBM (tunnel boring machine) is going to be repaired, and we will finish the tunnel drive, and open the tunnel to traffic,” Dixon said.

Matt Preedy, deputy administrator for the state’s Highway 99 project, said that until the 2,000-ton front end of Bertha is fixed, any schedules should be considered tentative.

Both men declined to discuss the total costs of delays and repairs, or who will pay what share, except that Dixon reiterated that Berthamaker Hitachi-Zosen of Japan is paying to retrofit the tunnel machine. They said the focus now is on restarting the dig.

 

Comments | More in Traffic & Transit | Topics: bertha, Highway 99 tunnel

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