Sustainable, diverse and walkable: The Bel-Red Corridor's Spring District hits all the buzzwords, even though it will be years before the first earth mover preps the site for development.

On Tuesday, Sen. Patty Murray joined a short roundtable session with Eastside leaders, transportation officials and developers to discuss future plans for the Bel-Red Corridor, and what the federal government might do to speed things along.

The 900-acre corridor, located just south of State Highway 520 between Interstate 405 and Overlake, is the route for the Sound Transit Eastlink light rail line between Bellevue and Redmond. Bellevue city officials have rezoned it to encourage transit-oriented development -- that is, dense urban housing and office buildings designed around the transit line.

Likely to be built first is the Spring District, Wright-Runstad & Co.'s 16-block development that would be centered around a light-rail station at 120th Street. It would accommodate 12,000 people who would either live or work there (probably, some would do both).

Murray has been talking up the Bel-Red Corridor back in D.C., and on Tuesday she seemed pleased to hear that developers, city planners and transportation agencies are collaborating on the project. The city is hoping for federal money from a sustainability grant to help pay for planning, and also has been trying to get federal money to build or extend some of the roadways that will be needed to connect the Bel-Red Corridor to the rest of the city. That includes an extension of 120th Street Avenue , and an extension of Northeast 4th Street to connect to 120th Street Avenue, said Bellevue Councilman Grant Degginger. The city will also have to build a new arterial, Northeast 15th/16th Street, to run east and west through the Bel-Red Corridor.

Meanwhile, Wright-Runstad is working with Sound Transit on a partnership that would put the developers in charge of building the transit station. Wright-Runstad wants the station to be built in a "retained cut," a kind of trench that separates the trains from surface traffic and would allow the city to build roadways across the tracks without needing traffic-slowing crossings. It's less expensive and easier to build than a tunnel, but the retained cut adds costs to the line -- an estimated $20 million. Under a public-private partnership, Wright-Runstad President Greg Johnson said, most of the cost can be financed creatively.

Johnson said the company hopes the economic climate will improve by 2013 to allow for the first apartments to be built in the Spring District. Light rail won't be built through the area until 2020, but in the meantime, he noted, the grocery store Whole Foods is within easy walking distance.

Murray called Bellevue "ahead of the curve" on its plans for the Bel-Red Corridor, and said she's a champion of the project. Both Murray and Johnson said they hoped the corridor could become a national model for transit-oriented, sustainable development.