The Coalition for a Sustainable SR 520 has filed a lawsuit that accuses the state Department of Transportation and the Federal Highway Administration of softpedaling the effects of a planned replacement bridge.

Seattle environmental attorney David Bricklin filed the papers Friday in federal court. That was the last day to challenge an environmental-impact statement that FHWA approved in early August. Bricklin's five-page, broadly worded complaint cites the statement's "failure to describe the project's unavoidable significant adverse impacts."

WashDOT has already hired builders for the east shore and floating bridge sections, but is at least $2 billion short of funding the Seattle landing.

"We are not opposed to a six lane bridge, but we are opposed to starting something the state can't finish," says Fran Conley, who coordinates the coalition of neighborhood and boating advocates.

In particular, she says, the proposed Montlake lid would carry hundreds of buses per day, ruining its purpose as a green refuge. State design drawings also depict approximately 160 feet width near Foster Island, so transit trains could be added someday in addition to the motor-vehicle lanes.

Over the last few months, the state has pointed to several changes made to reduce blight on neighbors and the city: a narrowed, 45 mph Portage Bay segment with landscaping, and lowering the floating deck from 30 feet to 20 feet in height. "We're confident we've been thorough and complete," said project spokeswoman Suanne Pelley.

The $4.65 billion project has been debated since 1997 and more than $263 million is already spent for design, engineering and public process.

A tax increase or tolls from nearby I-90 (currently banned by law, and opposed by Tim Eyman's I-1125) would be needed to finish the whole project from Seattle to Redmond.