The Alaskan Way Viaduct is a viaduct bridge in the city of Seattle, Washington, that carries Washington State Route 99 over the Elliott Bay waterfront between the city's Industrial District and Belltown. Originally opened in 1953, the structure was damaged in the 2001 Nisqually earthquake and has been proposed to be replaced by an underground tunnel.
Since 2001, the proposed replacement has been the source of much political consternation. Options for the structure – which carries 110,000 vehicles per day – have included replacing the viaduct with either a cut-and-cover or deep-bore tunnel, another elevated highway, or a surface highway; retrofitting the existing structure to improve its capability to withstand earthquakes; or outright eliminating the viaduct and making traffic-flow improvements to other north-south arterials to compensate.
On January 12, 2009, the state of Washington, King County, the city of Seattle, and the Port of Seattle revealed that they had agreed to replace the viaduct with a four-lane, 2-mile (3.2 km) long bored underground tunnel. The tunnel would have a south portal in SoDo, near Qwest Field, and a north portal in South Lake Union. On March 4, 2009, the state senate passed a bill endorsing the tunnel option.
The project is estimated to cost US$4.25 billion, with $2.8 billion coming from the state and federal governments to cover the tunnel boring and a new interchange in SoDo. The replacement project also includes the following projects and funding sources:
The announcement did little to quell the heated debate over the viaduct's replacement, with several factions expressing their criticism over the tunnel decision. Construction is proposed to begin in 2011, with the proposed tunnel opening in 2015  Some of the criticisms include:
The 1989 Loma Prieta earthquake destroyed the similarly designed Cypress Street Viaduct in Oakland, California with considerable loss of life. The 2001 Nisqually earthquake damaged the viaduct and its supporting Alaskan Way Seawall and required the Washington State Department of Transportation (WSDOT) to invest US$14.5 million in emergency repairs. Experts give a 1-in-20 chance that the viaduct could be shut down by an earthquake within the next decade. Since the Nisqually Earthquake occurred, the viaduct has been closed semi-annually for WSDOT to conduct inspections of the structure. Those inspections have discovered continuing settlement damage.
Due to damage from continuing settlement, a group of researchers and faculty from the University of Washington urged the mayor of Seattle (in 2007) to close the viaduct within a four-year timeframe.
Governor Christine Gregoire stated "no action" is not an option for the viaduct. However, she dismisses the idea of building a tunnel, and has not proposed any other plans or move towards repairs. There is consensus that some action needs to be taken with the viaduct and the seawall that supports the viaduct in the near future. However, there is no consensus on whether to remove, replace, or rebuild the viaduct.
Many Seattle leaders, including Mayor Greg Nickels and state and city transportation officials, favor building a tunnel. Plans for a six-lane, "cut-and-cover" double-decker tunnel were developed.[8 ] The tunnel was envisioned as a solution to not only the viaduct's traffic limitations and safety problems, but also to allow better uses for the waterfront real estate, including parks, housing, and retail developments. While future development of the Alaskan Way real estate corridor may provide tax revenue for the city, many state lawmakers claimed the originally proposed six-lane tunnel project was too costly. In response to concerns about the cost of the originally proposed tunnel construction, the city council created a scaled-down four-lane hybrid tunnel option.
On September 7, 2004, WSDOT announced that the alternatives had been narrowed down to two:
However, due to the costs and scope of the project, other options were still being discussed in the local media. Seattle City Council member Peter Steinbrueck noted that "While the mayor's first choice is the tunnel, he supports the City Council's resolution that designates a surface and transit alternative as a backup."
In mid-December 2006, Governor Gregoire stated the decision was at a stalemate and called for an advisory ballot on March 13 for Seattle residents.
On February 13, 2007, Governor Christine Gregoire rejected the scaled-down four-lane tunnel hybrid option, saying that the recent WSDOT review showed the tunnel proposal "does not meet state and federal safety standards." Of particular concern is that the use of shoulders as traffic lanes during peak traffic times would leave no additional lanes for emergency access. However, several of the viaduct "stakeholders committee" brought on board to advise the city have since indicated that the tunnel option should remain on the table.
Many prominent leaders and organizations are against an elevated structure and believe this is a unique opportunity to remove the viaduct and connect downtown Seattle to the waterfront. Former Governors Dan Evans and Gary Locke, former U.S. Senator Slade Gorton, and the American Institute of Architects recommend against rebuilding the viaduct.
This option was strongly backed by King County Executive Ron Sims, the People's Waterfront Coalition, and the Congress for the New Urbanism. This option was not on the March 13th ballot, but a rejection of the other two proposals could have indicated support for this alternative. The state and county currently have experts exploring the proposal and will report back to leaders when their assessment is complete.
Proponents offer examples of successes in other cities and outline the plan and its potential benefits as follows:
Due to removal, construction, or earthquake, there will be a multi-year period when the viaduct is closed. During this time, the city of Seattle could move forward with improvements to the downtown traffic grid and public transportation, while collecting information on whether additional transit capacity is needed. This approach would allow Seattle to determine whether it can replicate the success of The Embarcadero in San Francisco, despite Seattle's comparative lack of light rail and trolley transit.
On March 13, 2007, an advisory ballot allowed citizens to vote on whether they supported a surface-tunnel hybrid and whether they supported an elevated structure alternative. Voters rejected the surface-tunnel hybrid option 70% to 30% and rejected the elevated structure (rebuild) option 57% to 43%.
It was unclear what it would have meant if voters approved both options. Rejecting both options might have indicated a preference to earthquake-proof the existing viaduct or removal of the viaduct without replacing it.
In January 2008, as debate on its replacement continued, Governor Gregoire stated the State of Washington would take down the viaduct in 2012. On May 12, 2009, Governor Chris Gregoire signed Senate Bill 5758, authorizing $2.8 billion in state funds for a deep-bore tunnel. As of January 12, 2009, the state, county, and city governments along with the Port of Seattle have settled on the tunnel option.
Excavation for the cut-and-cover tunnel option would have involved both excavation along the waterfront and a re-excavation of the existing Battery Street Tunnel, which is level with the viaduct. Critics frequently mention Boston's Big Dig project, which among other work included a viaduct's conversion into an underground tunnel, as illustrating the schedule and budget challenges of such a large project. However, proponents have pointed out that Seattle's bored-tunnel proposal would not be close to the scale of even the cut-and-cover segment of Boston's I-93 tunnel project, which also included significant bolstering or relocation of rail, roads, utilities and subway tunnels above and adjacent to the work.
Mayor Greg Nickels is attempting to attract $1 billion of funding from the federal government; his department has also outlined a financial plan which adds additional sources of funding which potentially total $2.6 billion. With the termination of the Seattle Monorail Project, the Downtown Seattle Association is arguing for funding source used for the monorail project be used to replace the viaduct. The source for the monorail project was an excise tax based on tables approximating the value of vehicles registered within Seattle. The valuation tables have generated their own controversy, which resulted in the state wide tax vehicle excise being repealed.