Washington State Department of Transport has said that a busy Alaskan Way Viaduct is to close from tomorrow for two weeks while tunnelling work on the SR99 tunnel is undertaken.
The closure marks significant progress on the tunnelling scheme by contracting joint venture Seattle Tunnel Partners following almost two years of delays following technical issues and repairs to the tunnel boring machine.
The Hitachi Zosen TBM stopped work on the twin-deck 3.2km tunnel, which will replace the Alaskan Way Viaduct, in December 2014 after the cutterhead clogged and high temperature readings were recorded. Access shafts had to be constructed to bring the stricken TBM to the surface for repairs which took nine months longer to complete than initially forecast. The scheme has since been dogged with safety issues that have compounded delays.
According to the Department of Transport, closure of the viaduct, which is used by 90,000 vehicles per day, will enable better monitoring of the structure and allow for quick repairs if any ground movement from tunneling should occur.
“When we closed the viaduct for nine days in 2011, we saw significant congestion on Seattle city streets and nearby highways,” said David Sowers, deputy administrator of the Alaskan Way Viaduct Replacement Programme. “We’ll do everything we can to ease congestion, but unfortunately there’s no way to close a major highway without disrupting traffic.”