An independent expert panel that will be selected by Gov. Christine Gregoire and the Legislature's Senate and House transportation chairs, will play an important role in reviewing the feasibility of the tunnel and rebuild options to replace the Alaskan Way Viaduct and Seawall.

The review panel will consist of five to 10 experts in related fields, such as engineering, finance and transportation technologies.

Proposals from the Washington State Department of Transportation are due to the panel by July and the panel should report their findings to the city and state by September, said Joy Carpine, deputy communications manager for the Washington State Department of Transportation's Urban Corridors Office.

The Seattle City Council will then have the option of bringing an advisory vote before Seattle voters in November or adopting an ordinance that would decide the preferred alternative.

Sen. Erik Poulsen, D-West Seattle, thinks the "vote would put a lot of political pressure on the city to fulfill the public will."

But whether the Alaskan Way Viaduct is replaced by a tunnel or rebuilt, construction and closures along State Route 99 will detour traffic to and from West Seattle for several years.

The city and state have not yet developed plans for moving traffic during construction, which depending on the final building plan could last seven to 12 years, said Ron Paananen from the state transportation department. Those plans, along with a construction management approach, are expected later this year with a supplemental Environmental Impact Statement, he said.

One of Seattle's and the state's top concerns is how to efficiently accommodate commuters, transit, special event traffic and access to ferry terminals during the construction period. Blocking ferry terminals could cause traffic to congest other roadways, said Paananen, project director for the Alaskan Way Viaduct and Seawall Replacement Project.

Enhancing transit service, alternative routes, improved street systems and reducing automobile reliance with public transportation incentives are all options. Priority will be given to transit and trips that serve major destinations, industrial districts, retail districts and neighborhoods. Access for businesses, residents, institutions and construction workers along the construction corridor will also be given special consideration.

"I'm frustrated that more planning isn't taking place," said Poulsen. "In my heart of hearts, nothing will be enough to mitigate how upsetting the viaduct construction will be for West Seattle. It'll be a nightmare."

The city is still struggling to come up with funding for a tunnel to replace the 52-year-old earthquake-damaged viaduct, the city's preferred option that is estimated to cost $3.7 to $4.5 billion. Construction would start in 2008 and could last up to 10 years.

Currently the state has about $2.4 billion in committed funds for the project, $2.2 billion from the state gas-tax increase approved by voters last November, $231 million in federal funds and $177 million in nickel funds. Another $700 million is anticipated from the city and the Port of Seattle.

Paananen said the Port of Seattle would be committed to helping finance the project if it meets their goals of increasing freight mobility and better access to its port facilities.

"There's a lot of pressure on the city to prove that money for the tunnel is real and predictable and more than just hopes and prayers," said Poulsen.

About $800 million for the viaduct project has been earmarked under the Regional Transit Improvement District initiative that could go before voters in 2007. But the $7.2 billion transportation tax initiative that would provide money for road and bridge projects in Pierce, Snohomish and King counties could change between now and the vote, said Carpine.

Also, the initiative could be linked to a Sound Transit proposal, and in that case both must be approved for either to be implemented. Additional money could come from other agencies such as the Army Corp of Engineers and the state transportation board.

Another option is to build only the core of the tunnel; the south and central waterfront sections up to the Battery Street Tunnel, leaving the lower Aurora section for a later date. This option would cost between $3 billion and $3.6 billion, said Paananen.

With the committed and anticipated funds of about $3.15 billion, the core of the tunnel project is attainable, he said.

The tunnel would be built west of the existing viaduct, with north and south lanes stacked on top of one another along the central waterfront. The tunnel would replace the viaduct along the central waterfront and its west wall would replace the 71-year-old deteriorating seawall. The ground above would be a 180-foot wide public space.

The contingency plan is to rebuild the viaduct, which Poulsen said is most viable choice. That option would cost $2.6 to $3.1 billion and could take 12 years to complete. Tunnel opponents say the state already has enough money for the core of the rebuild ($2 billion to $2.4 billion) and should move ahead with the attainable plan. Construction for the rebuild would also begin in 2008.

The rebuild is extensive because construction would have to be conducted on top of the existing viaduct, said Paananen. But in some ways building a tunnel could be more convenient for drivers because it can be built to the side of existing viaduct while it's in use, said Paananen.

The new viaduct would be 25-feet wider and the lanes an extra 2-feet wide. Shoulders would also be added to the road. Cost analysis for both the tunnel and the rebuild were completed in December 2005 and included inflation and increased material costs. There have been no major changes to the cost or schedule of the project, said Paananen.

But with either option, construction is going to be a balancing act and will determine the length of impact for Seattle drivers.

The shortest construction time calls for more intense construction with complete closures of State Route 99. While the road closures are inconvenient for drivers, Paananen said that option would disrupt traffic for a shorter time and be less expensive.

The largest construction time would mean less intense construction, partial closures on the state highway, but longer traffic disruptions and higher project costs.

Visit www.wsdot.wa.gov/projects/viaduct or call 269-4421 for more project information/updates.

Rebekah Schilperoort can be reached at wseditor@robinsonnews.com or 932.0300.