A surface light-rail route should work well in downtown Bellevue, as long as the central train station is conveniently located, a panel of experts told Sound Transit this week in a report.

The positive tone goes against the view of Bellevue City Council members, who have unanimously endorsed a tunnel estimated to cost up to $350 million more than a surface route. The city is adamant about protecting its limited road space from conflicts caused by train crossings.

The six transit experts — from Portland, San Diego and Seattle — said Bellevue signals can be timed so that east-west Northeast Fourth Street flows well and takes priority. Trains might have to hold several seconds in the Bellevue Transit Center station before they head south across Fourth, for instance. Local-government forecasts of terrible gridlock in Bellevue also are driven by population and traffic growth, not train interference, they said.

In fact, the group is far more worried about delays for pedestrians than for cars.

Their "most important concern" is how the rail stop fits alongside the Bellevue Transit Center, where a projected 30 to 40 percent of train riders would transfer to or from a bus, the experts said. Members don't even like the idea of depositing train riders on the east flank of 110th Avenue Northeast, which would require people cross the street to the bus hub. They said one alternative is to run trains on 108th Avenue Northeast with a station inside the Bellevue Transit Center. But space is tight there for northbound trains to turn east, and the transit center would require a complete rebuild.

But the pro-surface analysis also acknowledged that track curves would cause screeching — and must be lubricated — where the trains bend toward I-405 from downtown. Noise has been a huge annoyance to homeowners along Sound Transit's initial line, near Mount Baker Station and in Tukwila.

There's also a "ripple effect" on the entire Link system if trains are delayed by a stall or collision crossing Bellevue streets, said Bernard van de Kamp, city regional projects manager. A typical East Link train in the 2020s would loop all the way through Overlake to the International District to Lynnwood, then come back.

The report is being presented Thursday at Sound Transit's regular board meeting. Bellevue City Manager Steve Sarkozy will discuss how the city might contribute $104 million to $150 million toward a tunnel. Options include earmarking tax income from related growth; providing free easements through city right-of-ways; and taking on road reconstruction costs related to the rail segment proposed along Bel-Red Road, east of downtown.

Sound Transit is scheduled to choose a favored downtown alignment April 22 for environmental studies, with a final decision due in 2011.