Gubernatorial candidate Dino Rossi's transportation "choices" plan would force Washington State voters to accept billions of dollars in roads that have already been rejected by voters or by state legislators. But, it turns out, that's the least of Rossi's problems.

Almost all the cost estimates in Rossi's proposal are based on assumptions that range from wildly optimistic to completely insane. Some of the highlights of Rossi's absurdist plan:

• The 520 bridge. Rossi's optimistic cost estimate for a new, eight-lane 520 bridge is actually based, bizarrely, on an estimate by his opponent, Governor Christine Gregoire, for a six-lane bridge; he arrives at the smaller figure by assuming construction happens sooner and adjusting his numbers accordingly. But that's not the only problem: Rossi's 520 plan doesn't account for all the extra traffic those eight lanes would dump onto I-5. According to Mark Hallenbeck, director of the Washington State Transportation Research Center, Rossi's bridge would require a total I-5 rebuild. "From a transportation planning perspective, you look at it and say you're creating as many problems as you're solving," Hallenbeck says.

• Expansion of I-405 by four lanes between Renton and Bellevue. Although differences between Rossi's proposal and one the state considered a few years back make it hard to compare the numbers directly, Rossi's estimate of $927 million is still more than $3 billion shy of what the Washington State Department of Transportation (WSDOT) estimated a longer expansion (from Tukwila to Bothell) would cost a few years ago.

• Tearing down the Alaskan Way Viaduct and replacing it with either a "tunnel lite" (like the one WSDOT rejected as unsafe in 2007) or a "deep bore tunnel." Mayor Greg Nickels's original tunnel-lite proposal came in at a (very rough) estimate of $3.4 billion; Rossi estimates that his tunnel will cost just $2.7 billion, without bothering to explain how he arrived at that number. Of the city's original estimate, Hallenbeck says, "That number was really invented by the city of Seattle to try to save the tunnel. I suspect that if you redid that number in the current world it would be higher."

• The Cross-Base Highway. The Cross-Base Highway in Pierce County was yanked from last year's roads and transit ballot measure because it would promote sprawl and traverse endangered oak prairie. Nonetheless, it's back in Rossi's plan, at a new and reduced price of $252 million (down from $308 million in WSDOT's estimate). Once again, Rossi fails to explain the savings.

• Rossi's plan allocates $200 million to fix 1,676 culverts that block migrating salmon. As the state Democratic Party has pointed out, Rossi's plan wildly underestimates how much fixing the culverts would cost. According to a 2007 report, WSDOT has repaired 69 salmon- blocking culverts since 1992, at an average cost of around $390,000. Rossi's plan, however, budgets just $100,000 per culvert—a number that's based on a WSDOT estimate from nearly 10 years ago.

Added up, Rossi's estimates are billions and billions of dollars less than what state engineers and transportation planners believe the projects in his plan will cost. Keeping in mind that studies have shown that virtually all large transportation projects end up over budget, not below, it's hard to see Rossi's rose-colored transportation proposal as anything more than transportation pornography being peddled to hard-up commuters by a candidate who'll say anything to get elected. recommended

barnett@thestranger.com