ANOTHER MILESTONE is reached for Sound Transit; a grand pronouncement is made. And we still don’t know where the trains are going to go.

Last week, the Sound Transit board of directors, which is made up of local elected officials, approved a $500 million funding agreement with the federal government. For light-rail promoters it was a landmark day, committing Sound Transit to building at least the northern half of its electric train system—from downtown to the University District—and committing the feds to help pay for it.

An enormous crowd of observers, many of them hostile to the project, packed the Sound Transit boardroom at Union Station, while several hundred more spectators were forced to listen to a booming broadcast of the proceedings from inside Union Station’s Great Hall. The event had a feeling of a die being cast. And yet this latest milestone is really going to kick off yet another round of reassessment, reengineering, and revision.

After a decade of study and four years past the election that created Sound Transit, the agency is still being forced to rethink where to put the light rail that we’ve just agreed to build. The exploding budget has thrown several key parts of the system into doubt, especially the tunnel under Capitol Hill. And so Sound Transit is embarking on a six-month “work program,” with a new set of “final decisions” now scheduled for July.

“There are changes that could reduce the cost of the project if the political will is there,” says Mike Vaska, an attorney with Foster, Pepper & Shefelman, who has been closely watching Sound Transit as a representative of the Greater Seattle Chamber of Commerce.

Last Tuesday, the chamber of commerce, which has heretofore been a strong public backer of light rail, joined with a more skeptical business organization, the Downtown Seattle Association, in penning a letter to Sound Transit board members, describing “grave concerns” about the project. The letter asked the board not to make any “irrevocable commitments” until a new Technical Advisory Committee has made “a thorough review.”

“Giving up the Capitol Hill tunnel has to be part of the debate,” Vaska argues. Boring through the Hill is considered the riskiest part of the light-rail plan, though also a rich source of riders. In the past, Sound Transit has examined routes that would bypass the Hill and run instead through the Eastlake neighborhood on the way to the University.

Another big cost driver in the current plan is the extremely deep tunnel that’s required to get under the Lake Washington Ship Canal and the correspondingly deep passenger stations that have to be built to meet it; these are expensive and full of construction hazards, not to mention inconvenient for riders. Sound Transit has in the past looked instead at building a bridge from the Roanoke neighborhood and sending the trains airborne onto Campus Parkway at the U.

Either of these choices would hugely disrupt a pair of Seattle neighborhoods that are, for the most part, wealthy, well-established, and well-organized. As Sound Transit notes in one of its briefing books, “Strong community opposition has been expressed in [the] past to a new bridge (due to concerns about noise, displacements, and view blockage).” Vaska comments, “It’s a political decision.”

And these decisions will be made in a highly charged political environment. Six months from now, the board will be well into campaign season, and several of Sound Transit’s board members—Mayor Paul Schell, King County Council member Greg Nickels, King County Executive Ron Sims, and McKenna, among them—will be in the midst of political races. To further complicate matters, Nickels and Schell might be opposing one another for mayor, and Sims and McKenna might face off for county exec.

SINCE VOTERS FIRST passed a tax increase to pay for Sound Transit four years ago, Sound Transit officials have skillfully shepherded their project along by imposing deadlines that seem both hard and soft—pushing the trains forward even while leaving options open, thereby making the project appear both inevitable and open to change. Last week’s board decision is just the latest example.

To defuse increasingly vocal opposition to light rail and sink its talons into federal money, Sound Transit staff went for a twofold strategy. It warned repeatedly of the need for the board to sign off on the “Full Funding Grant Agreement” immediately or risk having some other city receive the half-billion dollars in free money. At the same time, agency officials spread the word that this commitment wasn’t really such a commitment after all; the agency left the door open to abandoning the project in the future if some fatal flaw were discovered. As Sound Transit’s spokesperson Denny Fleenor put it, “We have the ability to give the money back.”

This notion came as a shock to at least some elected officials. State Senator Jim Horn of Mercer Island recalls a recent meeting in which Sound Transit officials tried to build support for the grant agreement among Eastside politicians. Horn says Sound Transit executives suggested that “if we didn’t want to follow through on the contract, we could just default.” He was surprised to see his fellow Eastsiders voicing approval for a strategy that included defaulting on a contract with the federal government. “I found that an unacceptable approach for elected officials,” he says.

Last week’s meeting to approve the Full Funding Grant Agreement carried a trumped-up urgency of its own. King County Council member Rob McKenna, the only Sound Transit board member to vote against the grant, pointed out that the board was being asked to accept the agreement without seeing it and without taking the 25 days normally allowed for review. Other board members contended that, as a “political” matter, approval was needed now before the change of administration in Washington, DC.

Despite the talk of default, it’s hard to imagine any development—whether sulfurous pits discovered beneath Capitol Hill, an immovable asteroid landing in the middle of Martin Luther King Way, or erection of a Great Wall of Tukwila—that could actually cause the politicians on Sound Transit’s board to change their minds and give back their right to hundreds of millions of dollars in federal cash.