Rising above or digging below? Community Club vets viaduct choices

For the city of Seattle - with its prickly traffic problems and notorious bureaucratic sluggishness - it is the question of the hour, the decade, perhaps even the century: Above, or below? Radically different, or haltingly similar?

The number of alternatives for fixing the decrepit Alaskan Way Viaduct and adjacent seawall now has been narrowed to just two, down from an original list of 76 concepts that have been bandied around in a seemingly endless series of public meetings. Those alternatives are as follows: building a stacked tunnel, by a method known as "cut and cover," or the creation of an elevated structure similar in its basic design to what now exists along the vaunted Seattle waterfront.

These choices were presented to the public last Thursday, Sept. 24, at the monthly general meeting of the Magnolia Community Club (MCC) held in the Catharine Blaine Elementary cafeteria and presided over by MCC president Vic Barry. The meeting, which featured a number of presentations and addresses by various public officials, ran well over two hours and was - relative to past meetings - sparsely attended by members of the Magnolia community.

Never a light consideration, replacing the 53-year-old viaduct now has become one of the city's most pressing priorities. The structure was damaged in the 2001 Nisqually quake, and it's been estimated that there's a 1-in-20 chance another earthquake will strike the region in the next decade. In segments of the viaduct, crumbling concrete and corroded rebar are visible, and exposed rebar is evident along portions of the deteriorated roadway. In the minds of many, and with memories of the 1991 San Francisco quake that caused roadway collapse along the Embarcadero, the viaduct has come to represent a tragedy waiting to happen.

Sen. Jeanne Kohl-Welles at the Thursday meeting emphasized the need to act promptly to avoid what she perceives as a disaster in the making. "The most important thing is to avoid delay," said Kohl-Welles, who - in opposition to both Rep. Mary Lou Dickerson and Rep. Helen Sommers - said she supports the tunnel alternative. "I can settle for a new aerial viaduct," she said, "but my preference is the cut-and-cover tunnel."

Mayor Greg Nickels also has come out in support of the tunnel alternative.

While the two options share many similarities - two-thirds of the tunnel and elevated structure will have the same design, both maintain transportation capacities and both have similar construction start dates - cost is not one. The full cost of the tunnel project is estimated to run between $3.7 and $4.6 billion; the elevated structure would cost between $2.7 and $3.1 billion. At its greatest disparity, the difference in cost exceeds $1 billion.

For her part, Kohl-Welles appeared sanguine about the greater price tag on the option she supports. "We know the cost is going to be enormous regardless of the selection," she said, adding that "with the cut-and-cover we get economic returns."

Such is not the case, however, with her compatriots. "This would be a big bite," Rep. Sommers said of the tunnel alternative. Conjuring images of Boston's "Big Dig" fiasco, Sommers said she can't support a project for which the funds aren't available. It's simply too expensive, she said.

Rep. Dickerson said she also opposes the tunnel option, mostly for reasons of money. "These projects usually go over budget by about 40 percent," she said, adding that, in addition to the viaduct, there is also the aging 520 floating bridge to worry about. "We don't have the money for it, [and] we do have the funding in hand right now to do the rebuild. We need to act."

Two other groups with members present at the meeting oppose the tunnel on the grounds of expense. The No Tunnel Alliance also referenced "the Boston-style Big Dig scam" in the literature they distributed - literature that listed such objections as "no to a 5 billion dollar tunnel to improve condo views" and "no to Nickels' tunnel and $500 million extra in utility taxes." And the Viaduct Preservation Group is calling for a retrofit of the existing viaduct, claiming that the financial, ecological and traffic impacts would be significantly reduced.

Craig Keller of the Viaduct Preservation Group said the viaduct is "a capacity that we can't afford to lose," adding that construction closures for any length of time could devastate the local economy through loss of jobs and a reduction in property values. He said his group hired an outside engineer to evaluate the viability of a retrofit, and it was found the viaduct could be prevented from collapsing without having to replace it. "This choice is a false choice," Keller said of the tunnel-versus-elevated structure option. "There is hope in this if we get the truth on these issues."

Kohl-Welles called comparisons of Boston's Big Dig and the tunnel option a "specious analogy," adding that the "total boondoggle" of the former has no similarities to Seattle's situation. Deputy Mayor Tim Ceis also refuted the Big Dig comparisons, pointing out that the cut-and-cover technique that would be used for the tunnel alternative is an altogether different process from the one used in Boston.

Ceis pointed out that cut-and-cover construction is fairly common. "This is the same kind of construction you'd see on I-90 going to Mercer Island," he said. "We have a lot of tunnels [like these] constructed in this area already. This is not new technology at all. This is a proven type of construction."

Rising up, rising down

"We have a great need to replace the viaduct," said project manager Mike Rigsby. "There are multiple failure paths that the viaduct can take." That threefold path includes superstructural failure due to the shaking caused by an earthquake, liquefaction of the soil supporting the viaduct and a loss of lateral support in the seawall. Rigsby added that the viaduct team had been through "an exhaustive process" evaluating alternatives and found that the tunnel and the elevated structure represented the best choices for replacing the viaduct.

The cut-and-cover tunnel would be a stacked structure, with three northbound lanes on bottom and three southbound lanes on top. Its dimension would be approximately 75 feet deep and 65 feet wide. The tunnel would be equipped with a ventilation system, a fire-suppression system and emergency exits. The west wall of the tunnel would become the new seawall along the central waterfront.

The elevated structure would be double decked, with three lanes of traffic in each direction. It would be about 60 feet high and 72 feet across (compared to the 50-foot width of the existing viaduct). The seawall would be replaced separately. Existing ramps on Columbia and Seneca streets, and on Elliott and Western avenues, would be rebuilt.

At the northern and southern termini of each alternative, the "footprints" would be similar; things would look about the same in either case. The major differences are along the central waterfront, or the span approximately from the stadium area to the Battery Street tunnel. Construction for either alternative would commence in 2010.

"These do represent the best thinking we have today on these options," Rigsby said, adding that the city is still looking at other structures that are "better, cheaper, faster."

Ceiss said the Seattle City Council on Sept. 11 introduced legislation to put an advisory ballot on the two alternatives for the viaduct in front of the public in November. He added that the council will act on the legislation this Friday, Sept. 22, and that "it's more probable than not" that the advisory vote will be on the November ballot.

Editor Rick Levin can be reached at (206) 461-1284 or by email at mageditor@nwlink.com.[[In-content Ad]]