Here's what will travel those light-rail tracks

Sound Transit rolled out its first Central Link light-rail vehicle on Monday.

The vehicle is only one element of the construction that will stretch from Westlake Station, in Seattle, to Seattle-Tacoma International Airport. When the light-rail line opens in 2009, riders can expect a 36-minute trip from Seattle to the airport.

Sound Transit plans to extend the rail so it will stretch to the University District. Other extensions have been proposed and could included lines stretching to Lynnwood, SeaTac, the Port of Tacoma and to the Eastside.

Trains will run every few minutes, 20 hours a day. Thirty-five light-rail cars will make up the initial fleet.

More than 45,000 daily riders are expected to use the link as part of their regular commute by 2020, said Seattle Mayor Greg Nickels, who also sits on the Sound Transit Board.

He said recent federal approval to expand light rail to the University of Washington gives local transit a bright future and "sets the stage for the next phase of developing the entire transit network."