New 520 could be a costly commute

Elected officials said Tuesday they've figured out how to pay for a new $4.4 billion floating bridge for Highway 520.

They want to create enthusiasm for this fall's huge "Roads & Transit" ballot measure, earlier versions of which drew criticism for shortchanging the bridge project.

Also, the Regional Transportation Investment District, a planning group of council members from Snohomish, King and Pierce counties, is legally required to produce a funding strategy for the bridge when it issues its final list of highway proposals Thursday.

"I think it's important for people to see that it's doable. We intend to do it," said state Rep. Judy Clibborn, D-Mercer Island and chair of the House Transportation Committee, who helped devise the new funding strategy.

It improves on earlier versions by saving an additional $340 million through low-cost financing and funneling savings in from other projects.

But future tolls might be double what officials previously discussed. Now, they're contemplating an average toll of $6 per round trip when the bridge opens late next decade, the same as the Tacoma Narrows Bridge will charge then.

The project remains a long way from ready.

Cost estimates are early and subject to change. The design has not been chosen. State lawmakers have not proposed specific tolls.

In a new development Tuesday, consultant Jim Waldo said the group is interested in exploring a leaner bridge — which entails narrower shoulders or lanes — accompanied by a reduced speed limit.

European cities use signs to set variable speed limits based on traffic and other conditions, a tactic many U.S. cities are studying. Last winter, Seattle Mayor Greg Nickels tried in vain to promote a waterfront Alaskan Way tunnel with a 35-mph speed limit at peak times, so the size and cost could be reduced.

The Highway 520 route through Seattle wetlands is so controversial that the state will hire a mediator to sort out conflicts among interest groups, neighbors, the city and transportation officials.

A thinner highway would presumably be more palatable to people who dislike a huge structure over wetlands on the Seattle side. Any savings would provide a cushion in case of spikes in material costs, said Kjris Lund, the RTID project manager.

The $4.4 billion figure is a midrange estimate for the "Pacific Street Interchange" bridge option, a relatively elaborate proposal that features an exit bridge over Union Bay, landing along Northeast Pacific Street at Husky Stadium; it avoids an interchange in the Montlake neighborhood.

The existing four-lane span, completed in 1963, could fail in the event of a severe windstorm or earthquake.

Its replacement and other highway projects will be combined with Sound Transit rail extensions in a joint ballot measure worth $17.7 billion in 2006 dollars, for construction and trains only.

Total spending would be about $37 billion to complete the work by 2027, if inflation, debt payments, operations, overhead and cash reserves are included.

Mike Lindblom: 206-515-5631 or mlindblom@seattletimes.com