UPDATED with map of new proposed alignment.

Sound Transit is tinkering with a new Eastside light-rail alignment that might serve downtown Bellevue without resorting to an expensive tunnel.

The latest concept, unveiled to transit-board members Thursday, would put tracks on the surface of 110^th Avenue Northeast, serve a station between the Bellevue Transit Center and City Hall, then go elevated at Northeast Sixth Street near Meydenbauer Center. From there, it would cross Interstate 405. The next station would be just north of Northeast Eighth Street, serving a redevelopment zone next to local hospitals.

That route avoids a major Achilles heel in Sound Transit's original surface option -- trains would have crossed busy Northeast Eighth Street every three minutes or so, risking traffic delays, accidents and a political backlash.

A peer-review panel suggested the new 110^th Avenue idea last month. Sound Transit's East Link project director, Don Billen, asked for and was give 2-1/2 extra months to study it, and other options, until the end of January. Then the agency's executive board, made up of local elected officials, would choose a preferred route for environmental studies.

"The time we spend upfront, trying to get it right, will have a positive effect on the schedule as we move forward," said transit-board member Fred Butler of Issaquah.

Sound Transit promised to reach downtown Bellevue by 2020, as part of the plan for three suburban lines that voters approved last fall. Since then, the city government endorsed a tunnel and pledged to seek an extra half-billion dollars or so in cost savings and revenue sources, a task complicated by the recession.

At least one tunneled route is still in play, beneath 110^th Avenue, but requires roughly $300 million more than a surface route, Sound Transit estimates.

Some rail supporters, including the Microsoft Corp., have urged Sound Transit not to spend so much time and money on downtown Bellevue that they delay extensions reaching Overlake and Redmond.