2010 is big year for progress on tunnel

Replacement plans for the Alaskan Way Viaduct are on track. But nine years after the Nisqually quake, the danger remains.
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The proposed waterfront tunnel

Replacement plans for the Alaskan Way Viaduct are on track. But nine years after the Nisqually quake, the danger remains.

One year ago, the governor, King County executive, Seattle mayor and Port of Seattle CEO stood together with labor, neighborhood, and business representatives to announce an agreement on the Alaskan Way Viaduct replacement. This marked a turning point in the effort to deal with a significant safety issue and replace this earthquake-damaged structure. Their recommendation: a bored tunnel beneath downtown Seattle, paired with surface street, transit, and waterfront investments. As we enter 2010 and approach some important milestones for the viaduct replacement, it'ꀙs important to remember how we got here and why it'ꀙs important to move forward.

In 2008 the state, county and city assembled a stakeholder group of almost 30 people, representing neighborhoods, business and freight interests, labor groups, and environmental and other cause-driven organizations, to review options for the viaduct'ꀙs central waterfront section. This open and transparent process gave members of the public a front-row seat as the agencies developed and analyzed replacement alternatives.

The group'ꀙs input made clear the competing factors any replacement would have to balance. The goal was to find a fiscally responsible solution that would open the waterfront while keeping people and goods moving, and one that could be built while minimizing construction impacts to the waterfront, downtown, and neighborhoods like Pioneer Square. As we initially evaluated surface and elevated options, many of the stakeholders expressed concerns about how such options would affect the waterfront and maintain mobility both during and after construction. The proposed bored tunnel was seen by many as the solution that would best balance all of these goals.

The current viaduct is a vital north-south route into and through Seattle'ꀙs downtown core, providing an alternative to already congested I-5 for people and goods. The proposed bored tunnel, which is estimated to cost approximately $2 billion (note, that'ꀙs a 'ꀜ2,'ꀝ not a 'ꀜ4'ꀝ), has several major advantages:

  • It would maintain a route for the 60 percent of viaduct users that bypass downtown, while providing access at its north and south ends for those heading into downtown and to activity centers like the stadiums and Seattle Center.
  • It would allow us to build the new corridor while SR 99 remains open to traffic, minimizing construction impacts to businesses and the traveling public.
  • Moving this traffic underground will allow Seattle to reclaim its downtown waterfront and create an inviting destination for residents and visitors.

During the last year, the public has played a key role in helping to refine the project'ꀙs design, through our north portal and south portal working groups and through the feedback we received at almost 100 community briefings and several public meetings. In December, after a series of value engineering exercises, we made changes to address neighborhood concerns and reduce risks and construction impacts.

The new design moves the tunnel'ꀙs south end away from Pioneer Square to limit impacts to this historic area and the potential need to reinforce older structures during construction. The new north end design moves the tunnel to Sixth Avenue N. to reduce the number of properties needed for this project and to improve our ability to keep people and goods moving on SR 99 during construction.

We recently reported to the legislature that the cost estimate for replacing the Alaskan Way Viaduct remains within the $3.1 billion budget established last year. This budget is made up of $2.4 billion from existing state and federal sources, up to $400 million from tolling revenue and a commitment of $300 million from the Port of Seattle. While the estimated cost for the bored tunnel increased by $60 million, to $1.96 billion, this increase was offset by savings elsewhere, including design improvements for the south end viaduct replacement. The recent design changes for the tunnel increased its overall length by 640 feet, but they also addressed significant risks identified during our estimating process. This updated estimate is based on an extensive cost and risk assessment, aided by a higher level of engineering detail and the involvement of independent experts and cost estimators experienced in tunnels and underground construction.

In our report, we also studied whether tolling could contribute up to $400 million in funding for the viaduct replacement. The Office of the State Treasurer found that four of the five scenarios we examined would generate close to or more than $400 million. Our traffic model analysis shows that some traffic would divert from a tolled tunnel to local streets and I-5, mostly during the midday, evening and weekend times when these routes are able to absorb additional trips, but travel times would stay the same or increase by two to four minutes.

As I mentioned earlier, 2010 will be an important year for the viaduct replacement. After formalizing an agreement with the city that outlines responsibilities for the viaduct replacement, we expect to enter into a similar agreement with the Port of Seattle, further strengthening our multi-agency effort.

In the spring, crews will begin construction to replace the southern mile of the viaduct, a project that will remove half of the vulnerable structure. The public will have an opportunity this fall to review a second supplemental draft environmental impact statement for the viaduct replacement. The document will look at how the transportation system functions, with a focus on the bored tunnel alternative, and will build upon the previous review of other replacement alternatives.

By the end of the year, four pre-qualified teams of international and national firms will bring their tunneling experience and innovative talents to bear on the bored tunnel with their proposals to complete its design and construct it. In these proposals we also expect to benefit from the currently favorable contracting environment, as demonstrated by the recent bids for the SR 520 pontoon construction project that came in $180 million below estimates.

Nine years after the Nisqually quake, the Alaskan Way Viaduct remains vulnerable to earthquakes and must be replaced. After much discussion and debate, we not only have an agreement on what should replace it, we have an agreement that makes sense based on the needs of SR 99 users and the needs of the city through which they travel. Further delay, which only heightens the safety risk and allows costs to increase, is not our friend.


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