Alaskan Way pre-qualifiers and cost review Jan 2010
Paula Wallis, TunnelTalk
- The results of a six-month cost and risk assessment for the proposed SR 99 bored tunnel to replace the Alaskan Way viaduct in Seattle concludes that the estimated cost of the tunnel construction increased slightly but, that the overall project remains within its $3.1 billion budget and that tolls could generate $400 million in funding for the replacement.
- The 2010 cost estimate for the proposed tunnel increased by about $60 million over the 2009 cost estimate (Fig 1). The increase is due to proposed changes to the alignment that will lengthen the tunnel by about 640ft (195m) (Fig 2). Currently the bored tunnel is about two miles (3.2km) long and is planned as a stacked-deck four-lane highway with two lanes in each direction.
- The proposed changes call for moving the alignment of the tunnel portals to lessen the curves to create a safer driving environment in the tunnel and reduce construction impacts. The changes include, moving the tunnel's south portal to Alaskan Way, to avoid impacting the Pioneer Square Historic District and reduce the number of buildings affected, as well as avoid construction difficulty and traffic disruptions during construction. The study also proposes moving the tunnel's north portal from Aurora Avenue to under Sixth Avenue. This would avoid complex and costly staging to keep traffic moving during construction, as well as reduce the right of way needs and the impacts to the businesses along the affected roadway.
- The Washington State Department of Transportation released the updated cost estimate and tolling study earlier this month, shortly after announcing the four design-build teams pre-qualified to bid on the tunnel replacement project.
- The short listed teams are:
Seattle Tunneling Group (STG) comprising S.A. Healy Company; FCC Construccion, S.A.; Parsons Transportation Group, Inc.; Halcrow, Inc
- Vinci/Traylor/Skanska (VTS JV); Arup
- AWV Joint Venture (KBB) of Kiewit Pacific Co.; Bilfinger Berger Ingenieurbau; AECOM
- Seattle Tunnel Partners (STP) comprising Dragados-USA; HNTB Corporation
Bored Tunnel Cost Estimate 2009 Cost Estimate(millions) Construction(including construction management) $1,062 Right of way $149 Preliminary and final design $118 Risk and escalation $571 Total $1900
Fig 1. Bored Tunnel Cost Estimates
Bored Tunnel Cost Estimate 2010 Cost Estimate(millions) Construction(including construction management) $1,224 Right of way $152 Preliminary and final design $169 Risk and escalation $415 Total $1960
- The state's contribution to the replacement program is capped at $2.8 billion, with $2.4 billion already committed through existing state and federal funding sources and up to $400 million assumed to be provided through tolls.
Fig 2. Newly proposed tunnel alignment
- WSDOT says RFQs (request for qualifications) will be issued on February 26, 2010 with the bid opening scheduled for January 2011 and planned opening of the tunnel scheduled for December 2015.
Alaskan Way bored tunnel agreement -TunnelTalk Oct 2009
Seattle's tunnel for viaduct replacement approved -TunnelTalk April 2009
Alaskan Way frustration -TunnelTalk Sept 2007
Washington State Department of Transportation
Add your comment
- Thank you for taking the time to share your thoughts and comments. You share in the wider tunnelling community, so please keep your comments smart and civil. Don't attack other readers personally, and keep your language professional.