Viaduct replacement crews digging giant launch hole for ferry-sized tunnel boring machineon August 23, 2012 @ 5:21 am (Updated: 9:52 am - 8/23/12 )
The project will be using the largest diameter tunnel boring machine ever built. The 57.5-foot diameter machine, which the Washington State Department of Transporation says is roughly the size of the Washington State Ferry system's largest vessel,* will enter the earth through a hole being dug in the construction area just west of Seattle's stadiums.
Matt Preedy, Alaskan Way Viaduct Replacement Program deputy administrator with WSDOT tells KING 5 they're preparing the hole for when the machine arrives next summer.
"The hole is big enough with just enough room to work around it to drop the tunnel boring machine into."
The launch pit will be a length of 400 feet, with a width and depth of 80 feet. Excavators will be pulling out 86,000 cubic yards of soil.
The tunnel boring machine will begin digging from the site in the summer of 2013.
The tunnel project is expected to be completed by December 2015.
*Washington State Ferries' largest boat, the Jumbo Mark II, has a 90 foot beam (width) and 17'3" draft. It's over 460 feet long and is able to carry 2,500 passengers and 202 cars.
There are three of these boats in Washington state, the Puyallup, Tacoma, and Wenatchee. On Thursday morning, the Puyallup was on the Edmonds-Kingston route and the Tacoma was on the Seattle-Bainbridge route.
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