Seattle input alters Highway 520 bridge design

The state is tweaking its Highway 520 bridge design, heeding several changes suggested by the Seattle City Council for the new six-lane toll bridge.

"I think under the current plans, they're going to be happy," said House Transportation Committee Chairwoman Judy Clibborn, D-Mercer Island.

Gov. Chris Gregoire is to announce the state's preferred alternative Thursday afternoon, and it will include plans to reduce future traffic through the Washington Park Arboretum and to build a leaner concrete roadway at the Seattle shoreline, compared with earlier plans, Clibborn said.

Bridge supporter Rep. Deb. Eddy, D-Kirkland, said the new version will have a "more friendly" urban design than typical highways.

Some general highlights:

• A direct ramp from the Washington Park Arboretum to eastbound 520 would be dropped, and other approaches could be limited to peak hours only, said Clibborn. These moves are meant to reduce Arboretum traffic and are more dramatic than what City Council members requested.

City Councilmember Mike O'Brien, as well as Paige Miller, executive director of the Arboretum Foundation, have suggested extra tolls on cars that use the Arboretum to reach the floating bridge and other moves to calm traffic.

• The section across Portage Bay, from the Montlake Interchange to Interstate 5, would be narrower and perhaps have a 45-mph speed limit, Clibborn said, to reduce noise and provide "more of a boulevard feel." Earlier, the state Department of Transportation (DOT) proposed a standard highway segment, with a new seventh lane for merges and exits.

• A second drawbridge would be included across Montlake Cut. King County Metro Transit needs those extra lanes to improve bus connections, but a plan for better transit flow has yet to be worked out, Eddy said. Seattle leaders also have called for room for new bike and pedestrian paths.

• An open-air gap would exist between new westbound and eastbound lanes at Foster Island, a change also promoted by Mayor Mike McGinn. If light rail is added someday, trains would exit from the middle and head directly toward the stadium station, presumably on a new Union Bay bridge.

Peter Hahn, Seattle transportation director, said he's heard some details and that "we're fairly confident" they reflect the city's ideas for the bridge, to open later this decade. DOT officials won't comment in advance of the governor's 2:30 p.m. Thursday news conference, nor would Richard Conlin, head of the City Council's Highway 520 committee.

Montlake neighborhood advocate Jonathan Dubman said a second drawbridge is unacceptable, while removing the Arboretum ramp just shifts the traffic jams. Except for the effect of bridge tolls, the DOT is failing to address congestion on city streets, he said. "They're past the point where they're trying to mollify us. They're not even talking to us," said Dubman.

The state will begin to construct floating pontoons and the Eastside section in 2011, though the finance plan remains $2 billion short of the entire $4.65 billion estimate.

Negotiations between the city and state will continue through fall, said Clibborn.

About 115,000 vehicles per weekday cross the floating bridge, which is 47 years old.

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