Hitachi Zosen Corp cemented its role in the SR 99 Tunnel Project on Wednesday by signing a contract with JV Seattle Tunnel Partners to supply the giant 17.5m diameter EPBM that will bore the 2.72km long tunnel beneath downtown Seattle. In July, Hitachi signed a letter of intent with the design-build contractor for the project. The letter of intent allowed the Japanese firm to begin preliminary design of the machine this summer. Washington State Department of Transportation (WSDOT) will pay Seattle Tunnel Partners approximately US$80M for the machine, an amount included in the tunnel project’s US$1.35bn contract.
“Signing this contract gets us one step closer to taking down the vulnerable Alaskan Way Viaduct,” said Gov. Chris Gregoire. “This state-of-the-art technology allows us to keep SR 99 – and the region’s economy – open for business during construction to replace this critical state highway.”
By signing the contract on Wednesday, Hitachi now can complete design of the machine, which will be barged to Seattle and assembled at the south end of downtown in early 2013. The machine will be launched from a pit near the Seattle sports stadiums where crews will begin demolishing the southern half of the viaduct next week. Demolition will require closure of the viaduct for nine days, beginning on Oct. 21.
“This will be a truly amazing machine,” state Transportation Secretary Paula Hammond said. “At nearly 1000m long, it will be about the same size as some of Washington State Ferries’ largest vessels.”
Later this month, crews will begin utility relocation and other preliminary tunnel work. Excavation of the tunnel launch pit will begin next year, followed by tunnel boring in mid-2013. The tunnel is scheduled to open to drivers in late 2015.
Hitachi was selected ahead of three other firms based on overall technical requirements, support capabilities, price and schedule. Based in Osaka, Japan, the firm has successfully built more than 1,300 TBMs, a number of them for large-diameter tunnel projects. They are currently supplying the TBMs for Sound Transit’s Capitol Hill Station to Pine Street segment and the Bay Tunnel near San Francisco, Calif.