As the Seattle City Council took an incremental vote Monday, April 23, on replacement of the Highway 520 floating bridge across Lake Washington, a lot of things were unclear, but one thing was very clear: This process is supposed to be different from the Alaskan Way Viaduct fiasco. Lessons learned, and all that. That's what people kept saying. No one wants another war between the city and the state, with little to show from the rancor but lost time and money, a bruised electorate, and a sense of futility for those stuck in traffic. But at least from one perspective, 520 already feels like a transportation Ground Hog Day. For starters, the two structures present challenges that are eerily comparable. Both are old and crumbling, vulnerable to earthquakes. Both are essential to our overwhelmed and fragile network of roads, each carrying more than 100,000 cars a day. Replacement of either is hideously expensive and disruptive, with costs outstripping budgets. Politically, talk of replacement is poisonous, given the warring around transportation projects, the gulf between Seattle and the suburbs, and the imperative to stop global warming by standing against the carbon-burning automobile. Yesterday, the council endorsed a resolution establishing principles for the future 520 project, just as it did years earlier for the Viaduct. The 520 principles call for good design, lots of transit, improvements for bicyclists and pedestrians, minimal impact on the environment and the Arboretum, and even an analysis of the project's "carbon footprint." (Nothing bigger than size 12.) The state Department of Transportation is told to coordinate bridge planning with work on Sound Transit's Montlake light rail station. And make sure to "mitigate impacts" on neighborhoods and the University of Washington. Oh, yes, the university, Balrog in the basement. Missing from the resolution is the council's assessment of the Pacific Interchange option, a six-lane proposal conceived by some Montlake neighborhood activists that has won strong support on both sides of Lake Washington. The omission is intentional. Supporting the Pacific Interchange option, or any option, would ignite controversy, adding to opposition that already exists among those who want a bridge no bigger than four lanes. The real guiding principle is to avoid another Viaduct war. So keep calm. Build confidence. Nothing's final here. One step at a time. In 2004, the city and the state faced a difficult choice over the Viaduct, Seattle's elevated waterfront freeway. Elevated or tunnel? The mayor and the council approved a deal with the state that said tunnel, unless money ran short, in which case it was elevated. So both options went forward for study, costs rose, and three years later the electeds gave it to the voters, who said no to both. Since doing nothing was unacceptable, work will begin on the south and north ends of the Viaduct, putting off for later what to do about the mile along Seattle's central waterfront. Which brings us back to 520, where we also see a strong desire to finesse the unpleasant but assume a risk about the future. Those who push the Pacific Interchange option saw a partial victory in yesterday's vote, momentum for their cause. But to pick one tender point, the Pacific Interchange would cost $4.4 billion. If you look skeptically at funding, as we learned to do late in the Viaduct process, that could be as much as $2 billion more than is likely to be available for the project. More money could come from such sources as a tax proposal on the ballot in November, but it's already in trouble with some environmentalists. In Seattle, these big transportation projects are hard to do, but in the doing, what gets done?