On Tuesday, March 2, the City of Seattle and State of Washington hosted an open house so visitors might come to understand the worth of replacing the Alaskan Way Viaduct with a tunnel. In the Seattle aquarium, across from the viaduct, people jockeyed for position between easels and gurgling marine exhibits, trying to glimpse drawings of a future Alaskan Way, wide, sunny and absent of the waterfront's hulking concrete wall.

Expert explanations came from members of the city and state's departments of transportation. Shortly after 5pm, a lectern appeared, followed by a microphone, cameramen and finally, the mayor, who welcomed everyone and said he was confident funding would be found for an Alaskan Way Tunnel. There was enthusiastic applause.

In Olympia, the reaction was less enthusiastic.

"We need to stop dithering and make our decision and move forward. We've given the mayor long enough," said Representative Mary Lou Dickerson (D-Seattle) who, on the previous Tuesday, introduced legislation that would have required the state to pick whatever viaduct option it could afford by April 1. That would have meant that unless the mayor's office could find about $1 billion in three weeks, a rebuilt Alaskan Way Viaduct would be on order.

Two days later, Dickerson threw her support behind Representative Ed Murray's (D-Seattle) alternative proposal, giving the state until January to come up with funds for a replacement tunnel. Dickerson hadn't softened her stance on wanting a replacement for the viaduct quickly. She just knew her proposal wouldn't have cleared the senate, and that any time line was better than none.

"In the world of legislature, compromise is better than nothing," she said.

And in the world of state mega-projects, sooner is better than later. At least that was the resounding message from the House Transportation Committee, which passed Dickerson's April 1 deadline language by a whopping 26-2 vote. Committee members outside Seattle are likely worried that a costly tunnel could siphon away cash from other needed regional transportation projects, like the SR 520 floating bridge, and Interstate 405.

Dickerson herself said she introduced the legislation because she worried about commuters plying a creaky viaduct while the state fritters away money designing a tunnel Seattle can't afford.

But the mayor's office sees a rebuilt viaduct as shortsighted. Their argument is that this is the only opportunity, in most voters' lifetimes, to turn Seattle's crowded, battleship gray waterfront hillside into an elegant, welcoming, public promenade. The difference of opinions equals about $500 million.

Costs for the tunnel are given in ranges but roughly $3.6 billion is needed. So far, the city and state have earmarked about $2.5 billion for the project, most of that coming from the gas tax increase that was on the ballot for repeal last year. The city says it has access to another $500 million through various means, and the Port of Seattle will kick in another $200 million. The $3.2 billion is enough to get the viaduct rebuilt, but not replaced.

"We're very close to funding the tunnel," said Patrice Gillespie Smith, a spokesperson for the city's department of transportation.

Smith described five options as "solid prospects" for funding the final $500 million, including tolls on King County roads, a regional funding ballot and various federal handouts.

While the solidity of some of these ideas is debatable - imagine bleary-eyed Eastsiders supporting Seattle's waterfront views by throwing change in floating bridge tollbooths every morning - getting federal money seems perfectly reasonable. Especially given the clout of U.S. Senator Patty Murray, who has a successful track record in getting money for Seattle causes, most recently rescuing the Ballard Locks from a budget shortfall.

The main selling point of the tunnel is the rebirth of Alaskan Way, and the city is not short on ideas for how to use new waterfront property downtown. Some design plans that have been developed call for improvements to ferry docks, others for streetcar service along graceful, wide, tree-lined streets. Even skateboarding elements have been considered. But the most striking changes, if artist's renderings have it right, are sunshine on Alaskan Way, and a redevelopment boom for properties formerly walled off from the waterfront by the viaduct.

The city even has a Waterfront Development Plan, with an advisory council of developers, landscapers and environmentalists to help incubate future uses. Such plans probably contribute to the belief by some opponents that a development land grab is the primary driver of the tunnel idea and the void left by the viaduct will be filled with towering condominiums.

But that's not even possible, according to John White, an engineering manager with the Washington State Department of Transportation charged with the tunnel's preliminary design work. White said that though plans are tentative, the cover over the top of the tunnel might be as little as eight feet thick, much too thin to act as a foundation for large buildings.

"There wouldn't be any ... major structures above the tunnel. You'd have a pedestrian corridor with [possibly] a trolley..."he said.

Tunnel vision

According to White, the tentative plan for replacing the viaduct includes two three-lane tunnels. One of the tunnels, holding the southbound lanes, would be stacked on top of the northbound traffic tunnel, and run in a roughly 100 foot wide trench under Alaskan Way between Pine Street and South King Street.

The stack tunnel idea is a new wrinkle. White said the change from two parallel tunnels as originally envisioned is partly due to a better understanding of the space requirements needed for the utility corridor that will be buried next to the tunnel. Engineers are considering how to get water, sewage, high voltage power lines, data and voice connections and even steam pipes into an economic space, while still keeping the individual utility lines far enough from each other to satisfy safety regulations.

"There are major utility considerations with either project," White said.

There are also major industrial considerations with either project. Representative Dickerson said that the "vast majority" of her constituents in Ballard support the rebuilt viaduct and some of her constituents are certainly concerned about the tunnel's potential impact on trucks.

Ballard and Interbay, in north Seattle, and the Duwamish area in south, form a kind of industrial hourglass in the city with State Route 99 and the viaduct being the artery - or choke point - for trade between the two strongly interdependent centers.

A tunnel would be off limits to trucks carrying combustible loads, most notably petroleum, which is distributed to Ballard from tank farms on Harbor Island. Presumably, those trucks would, presumably, have to travel down the pedestrian-rich Alaskan Way surface road instead.

Of broader concern is how trucks will handle two steep sections of the tunnel, both at seven percent grade. Trucks laden with cargo would slow on these sections, reducing the overall throughput of the system.

"That's if people can get up the hill. If there isn't any stalling," said Eugene Hoglund, a retired Boeing electrician and, industrial advocate and vocal critic of the tunnel. Hoglund says the mayor is unconcerned with negative effects the tunnel would have on business.

The State's White acknowledged that freight experts' alarm thresholds were set around seven percent grade and that the state is studying potential solutions for mitigating one such stretch at the north end of the tunnel. Further south, the other seven percent grade sits in an area WSDOT refers to as the Central Waterfront Hump, where the proposed tunnel would intersect with the Burlington Northern train tunnel, which stretches about a mile from below Virginia Street, emerging at the King Street Train Station. Negotiating that tunnel, without a steep rise at some point, may not be possible, White said.

But just building the tunnel will be a huge challenge.

"We haven't really done a project like this. It's very unique," White said. The engineer struggled to find another tunnel project - inside or outside Washington State - that would be comparable.

The cut and cover plan for building the tunnel is conceptually simple; dig a trench, build a tunnel in it and then cover it. But the two types of material where the trench must be cut makes the project problematic. One variety - a hard soil made of sand and silt, sits at the bottom of the trench and another, a waterlogged fill soil, sits above it. The fill soil is prone to movement, especially during earthquakes. The cracks in the existing viaduct, cracks driving the structure's replacement, attest to this.

The fill soil also originates from Denny Regrade project of almost a century ago and likely contains waterfront detritus left over from the 19th Century Alaskan Way - wooden beams, construction equipment, even portions of old railroad track could be stuck in the fill.

"As many holes as you punch in the ground...there's going to be surprises," White said.

The state department of transportation is continuing with preliminary design work on the tunnel. Partly this is because the tunnel is the preferred alternative, and partly because delay, on a project of this size, can have staggering costs.

"If the tables get turned, you could see a scenarios for doing some design work for something that isn't going to be built. You take some appropriate risks to save money. Even if it backfired and we had to switch gears, it's just a drop in the bucket to delaying the whole project," White said.

That's because, if for no other reason than inflation, every day sees the project cost more. For financial reasons, and structural ones, the clock is ticking on the Alaskan Way Viaduct.