IT DIDN'T MAKE the daily newspapers, but City Council Member Heidi Wills' recent high-decibel performance in colleague Peter Steinbrueck's office was the lead story among city hall staffers for days. "She lost it," says one staffer. "I could hear her yelling all the way from my office."

Why was Wills so agitated? Simple: She supports light rail, and Steinbrueck had the temerity to sign a letter rejecting a proposal by Wills' ex-boss, county exec Ron Sims, to find new funds for light rail. Steinbrueck then went on to add his name to the "Sane Transit" coalition, a group of nearly 100 folks, that includes former Governor Booth Gardner and former Director of Metro Transit Chuck Collins. The coalition is demanding an independent audit of Sound Transit. The letter Steinbrueck signed was a stern request that Sound Transit--created by voters in 1996 to build light rail from the U-District to SeaTac--show its math before taking $500 million in federal money. If Sound Transit takes the money (due to be approved in October) without first answering questions, taxpayers may be locked into a project plagued by unknowns that could add up to $500 million in extra costs.

Steinbrueck says, "$500 million in overruns is a hemorrhaging of the public trough. It will likely get much worse if we don't get greater accountability. Why should [Sound Transit] fear an independent audit?"

In short, Steinbrueck and others want a reality check on Sound Transit's costs, and adamant light-rail advocates are nervous.

With a popular liberal like Steinbrueck raising concerns, the light-rail fast track has hit a monumental speed bump. Bashing Sound Transit (or at least raising questions about the project) apparently isn't just for disenfranchised neighborhoods anymore. Indeed, in addition to Steinbrueck (who could become mayor by simply smiling at editorial boards), downtown insiders and politicians alike are taking action. In a vote last week, County Council Member Maggi Fimia sabotaged Sims' $320 million light-rail rescue mission, while the weighty Downtown Seattle Association (DSA)--which reluctantly came back into Mayor Schell's Sound Transit fold last June--held a frantic succession of executive meetings to figure out if it still wanted to support the project. In fact, DSA board member and officer Matt Griffin has already signed the audit letter.

Light-rail critics have straightforward concerns: What's the real price tag for the 22-mile light-rail line? Who's paying for it? Sound Transit sets the bill at $1.9 billion. In 1996, voters agreed to pony up $1 billion in taxes. The rest is to come from bonds, fares, and the Feds. However, audit advocates--led by Emory Bundy, director of longtime environmental group the Bullitt Foundation--say things have gone wrong.

· There's $500 million in possible extra costs related to Beacon Hill, the King County bus tunnel, and mitigations in Rainier Valley and at the University of Washington.

· Sound Transit's per-mile construction estimates are out of whack with other light-rail projects. Using Los Angeles' experience, Bundy says the Beacon Hill tunnel will cost $200 million--not $75 million as Sound Transit estimates.

· Sound Transit's plan to defer or delete nearly 20 percent of planned stations will result in lost fare revenues.

· Sound Transit's proposal for federal money obligates areas like Redmond to help fund Seattle's Capitol Hill tunnel. Voters prohibited regional cost-sharing.

Sound Transit spokesperson Denny Fleenor acknowledges $7 to $11 million in extra UW costs, but otherwise dismisses the doomsayers. He argues that King County tunnel and Beacon Hill price tags are accounted for. He also says comparing L.A. to Seattle is not "apples to apples." Finally, he counters critics with a federally mandated audit by Diversified Capitol Inc. (DCI). The audit concluded that Sound Transit can easily complete an initial 7.2-mile segment of the light-rail line.

But Bundy scoffs at that audit. "Those of us who want an audit want it for the whole project, not for just the first seven miles. The nightmare scenario is that we build [the initial seven miles], by which time our resources and tolerance are exhausted. Then we're left with a multibillion-dollar line that enables people to ride from Capitol Hill to downtown." Bundy also questions the credibility of DCI's audit by quoting the audit itself: "Since data provided by Sound Transit were assumed to be accurate," a DCI disclaimer reads, "any inherent limitations, errors or irregularities that occurred may not be detected."