The Seattle Department of Transportation had to file an official public records request with the Washington State Department of Transportation to obtain a copy of a contractor's review saying there are no insurmountable problems with the city's slimmed-down hybrid tunnel proposal.

State officials pronounced the hybrid tunnel plan unsafe because emergency vehicles would not be able to get through traffic during the morning and evening commute times. During rush hours, traffic in the four-lane hybrid tunnel would be allowed to drive on the 14-foot-wide shoulders to create six lanes, with 2 feet of clearance.

City transportation officials knew the contractor firm Parsons-Brinckerhoff had performed a "screening level review" of the four-lane hybrid tunnel proposal showing its design would work, Hirakawa said recently, but the document was never given to the city before the official request was filed.

"We knew there was no fatal flaw because we had been involved for five years in the project," Hirakawa said.

The original tunnel proposal was to have six lanes but when it was apparent the Legislature wasn't going to appropriate enough money to build it, the city of Seattle proposed a four-lane version of the cut-and-cover tunnel. City officials are perplexed that their idea was deemed feasible by Parsons-Brinckerhoff, yet state officials, including Governor Chris Gregoire, now say no.

Hirakawa pointed out that the 520 Bridge has 1 foot of clearance. Interstate 90's Mount Baker Tunnel has tight clearance as well, he said.

Hirakawa shared other information with the Delridge Neighborhoods District Council about the planned replacement of the Alaskan Way Viaduct too.

The Seattle City Council unanimously passed a resolution in January, with agreement from Mayor Greg Nickels, to start working at the southern end of the massive project. That could mean the Spokane Street Viaduct could be widened and a new off-ramp built at Fourth Avenue South. There are also plans to build a bridge over the railroad tracks by Lander Street south of downtown.

Work on the proposed new interchange west of the stadiums would start sooner than other parts of the waterfront project too, Hirakawa said.

An agreement on how to deal with cost overruns was negotiated a few months ago, but it has not been ratified, he said.

The state of Washington agreed to pay for the cost of a new viaduct including normal overruns, such as inflation on construction materials to build a new viaduct.

The city, on the other hand, would share the cost of overruns for items specifically needed to build a tunnel, Hirakawa said. The city, for example, would share with the state the cost of geotechnical analysis necessary to dig a cut-and-cover tunnel, he said.

One way the city plans to generate money is to create a "local improvement district" that would include much of downtown. The argument is that downtown property owners would benefit by gaining a better view of Puget Sound, which would increase the value of their downtown property, Hirakawa explained.

The local improvement district could extend from Broad Street at the north to the stadium area near Atlantic Street. It would run from Fourth Avenue to the waterfront. Property owners in that slice of downtown would pay higher property taxes if a tunnel were built.

The goal would be to collect a total of $250 million from the local improvement district, Hirakawa said.

Studies indicate the improved views from demolition of the Alaskan Way Viaduct would be worth $400 million to $600 million to downtown property owners. Hirakawa said the fees would be added to property tax bills of downtown property owners.

Tim St. Clair can be reached at tstclair@robinsonnews.com or 932-0300.