Three members of the Bellevue City Council were all ears Wednesday night when a California rails-and-trails advocacy group told how they mustered voter support for a 70-mile commuter rail line through Marin and Sonoma counties -- complete with a bike trail along the entire route.

Why are rails-with-trails so interesting to Eastsiders? Because the Port of Seattle last year purchased the BNSF Railwayrail corridor, which runs through the Eastside from Renton to Woodinville, and on to the town of Snohomish in Snohomish County.

There's a $50 million chunk of voter-approved money in the Sound Transit budget that could be used in partnership with a private firm to help get a commuter train running on the BNSF corridor.

And there are some aggressive players who want to see a commuter rail line brought to this area, fast.

On Wednesday, the Cascadia Center of the Discovery Institute organized a bus tour along the rail line. (The center is a public policy think thank that's been advocating rail options.) Newly-elected councilman Kevin Wallace went along for the bus ride (he could be heard talking up the benefits of the Vision Line alignment for East Link light rail with a councilman in a neighboring city). For dinner, Mayor Don Davidson and Councilwoman Claudia Balducci joined the group, along with council members from Redmond, Newcastle, Woodinville and elsewhere.

About that $50 million. Sound Transit is likely to issue a request for proposals, possibly later this year, to try to find companies that would be interested in partnering with the agency to bring some kind of commuter rail to the Eastside, using the BNSF line, said Joni Earl, Sound Transit chief executive officer.

Who would be interested? Doug Engle, the chief financial officer of GNP Railway Inc.,laid out an aggressive, ambitious plan to convert portions of the rail line into a commuter service line in years, rather than decades. A special rail-fixing machine could be used to repair and renovate the line while simultaneously removing the old rocks, or ballast, from underneath the rails and creating a gravel pathway next to the line -- the base layer for a new bikeway. And Engle claimed the company could do the renovations for one-tenth the cost a public agency would pay, renovating a mile of track a day.

That raised a few eyebrows in the room.Earl wanted to know why GNP could do the work without jumping through all the environmental hoops that would be required of a state agency. Engle's answer: GNP recently won federal government recognition as a federal railway.

"The beautiful part of being a federal railway," said Engle, "is the state has no jurisdiction over us."

In other words, GNP wouldn't have to jump through environmental regulations because it's a recognized railway, using an existing rail line that was very recently used for trains. The fixes to the rail line, and yes, even building the bike lane, would amount to maintenance work, Engle said.

Even Cascade Bicycle Club president Chuck Ayers, also at the meeting, seemed intrigued by the idea of simultaneously building a commuter rail and a bike trail in the corridor, and doing it fast.

But Shawn Etchevers, a member of the steering committee for Eastside Trail Advocates, said his group is leery of the idea of running a rail line through the entire corridor.

In the Houghton neighborhood of Kirkland, the railway is narrow and houses back up right next to the line. Etchevers' group's mission is to create pedestrian and biking trails along the corridor. The entire line would make a great walking and biking trail, he said. But in some narrow places, Etchevers says, a rail line just doesn't fit.