Savings with tunnel plan challenged

OLYMPIA — A top state transportation manager raised doubts Thursday about whether a narrower tunnel to replace the Alaskan Way Viaduct really can save $1.2 billion, as touted by Seattle officials.

The city's advisory measure for the March 13 ballot says a four-lane tunnel — with safety shoulders used as exit lanes at rush hour — can be built for an estimated $3.4 billion. That idea emerged after the expected price of a six-lane tunnel rose to $4.6 billion last year.

But David Dye, urban-corridors administrator for the Department of Transportation (DOT), speculates that the city is being optimistic about its bottom line.

"It could be as low as $3.4 billion, but it could be higher. It will probably be between $3.4 billion and $4.6 billion," he told the Senate Transportation Committee.

City officials said Dye's comments are all the more reason to keep studying its new tunnel proposal and verify the cost estimates before the election.

The ballot will ask voters to declare yes or no on two replacement options for the viaduct: The narrower tunnel and a $2.8 billion, six-lane elevated highway.

Seattle Mayor Greg Nickels and most members of the City Council support the tunnel. House Speaker Frank Chopp wants an elevated highway.

An expert panel appointed by the state to examine viaduct options said this month a four-lane tunnel "shows promise," but the state halted its review. The city on Thursday offered to pay for more study, but Gov. Christine Gregoire has not answered its request.

The panel last year suggested the DOT and the city consider a shallow tunnel with the lanes side by side, instead of the deeper, stacked tunnel recommended by the state.

The city says it would save $100 million with the four-lane tunnel by forgoing improvements to the Battery Street Tunnel north of the viaduct on Highway 99. But Dye said he wasn't sure he'd support postponing that work, which would include new lights and sprinklers.

He also questioned whether the four-lane tunnel would dramatically reduce utility-relocation costs and whether construction schedules can be shortened enough to save $200 million. The city counts on both of those savings in its tunnel plan.

Even if Dye is partly correct, Seattle transportation Director Grace Crunican said there's enough savings, plus additional revenue from tolls, the Port of Seattle or federal aid to make the plan affordable.

Deputy Mayor Tim Ceis told senators the tunnel could be built without money from an expected regional roads-tax measure this fall.

The state already has pledged more than $2 billion in gasoline taxes to replace the viaduct with either a tunnel or an elevated highway.

The Alaskan Way Viaduct, built in 1953, was damaged by the 2001 Nisqually earthquake and is vulnerable to collapse in another quake.

Mike Lindblom: 206-515-5631 or mlindblom@seattletimes.com