"Pacific Interchange" plan for Highway 520 gains momentum

As momentum builds for the six-lane "Pacific Interchange" option on a new Highway 520, Mayor Greg Nickels is urging the City Council to slow down until more is known about how a new highway would affect the University of Washington and its arboretum.

Thursday morning, council members Jan Drago and Richard Conlin released a draft resolution backing the Pacific Interchange plan. A council vote is expected in the next few weeks.

Nickels replied in a letter: "While a six-lane alternative may have transportation benefits to the city and the region, the state has not adequately analyzed the environmental impacts on Seattle's cherished Arboretum, the surrounding wetlands, neighborhoods or the University of Washington. Only when these conditions are fully understood and the state has confirmed its intent to provide appropriate mitigation should we make this decision."

For years, governments on both sides of Lake Washington have argued over whether to replace the feeble four-lane bridge, which opened in 1963, with a four-, six- or eight-lane span.

The Pacific Interchange represents a possible solution.

A six-lane span lets transit buses run in new high-occupancy vehicle lanes to reduce trip times, an improvement that Drago called "a vital task."

Bellevue officials also are working on a statement supporting the Pacific Interchange.

Elected officials have not figured out how to pay for a new bridge, estimated to cost $4.4 billion, possibly as much as $5.3 billion.

The Pacific Interchange concept was devised by Montlake residents; it would spare their neighborhood an enlarged interchange and nine lanes — including ramps — over Portage Bay by moving the complex farther east.

A high-level overpass would begin on Foster Island and cross Marsh Island, ending near Husky Stadium. The existing Montlake Bridge would accommodate mostly local traffic, while vehicles from outside the area would arrive via the overpass. Montlake Boulevard Northeast would be widened from four lanes to six.

The UW has "serious concerns about the impacts," said Aaron Hoard, UW's deputy director for regional affairs, who cited four issues to be negotiated:

• The Arboretum. People who walk or canoe in the Washington Park Arboretum would encounter more columns and ramps. The Arboretum's advisory committee issued a statement this month saying a new highway and its shadows would threaten native plants.

• University lands to be taken for the project, including parking lots next to Montlake Boulevard and south of the stadium.

• Construction work that delays people going to the University of Washington Medical Center or sports events, at the same time Sound Transit builds a proposed light-rail station.

• Urban design. Does a road expansion visually sever the main campus from sports facilities east of Montlake Boulevard or encroach on the Burke-Gilman Trail? "People need to understand there's 60,000 people on campus," said Hoard. "We think of ourselves as a particular neighborhood of sorts."

Seattle's draft resolution suggests several conditions, including reduced lane and shoulder widths, to reduce effects on wetlands and views.

In related news, tests Thursday on soil in the area, which WSDOT initially thought to be contaminated with petroleum, did not show hazardous material.

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

Times reporter Ashley Bach contributed to this report.