Sound Transit can go ahead and build light-rail tracks in the express lanes of the Interstate 90 floating bridge, a judge ruled this week.

Bellevue developer Kemper Freeman, known as a pro-driving advocate, had sued to block the project. His attorneys argued that the state Department of Transportation (DOT) was violating the state constitution by making a deal with Sound Transit to use highway lanes — which are built using gasoline taxes — for transit, which is a non-highway purpose.

But Judge Michael Cooper of Kittitas County Superior Court ruled DOT wasn't misusing highway dollars, because carpool lanes will be built first on I-90, to replace the lanes Sound Transit will take. Sound Transit dollars will reimburse DOT for most of the $188 million carpool-lane project.

Last year, the state Supreme Court heard some preliminary arguments, but made a largely procedural ruling favoring the agencies, saying Freeman v. Gregoire should first be heard in lower court. So Freeman refiled the case in Kittitas County, thinking that would be neutral territory.

Sound Transit extolled the ruling Friday, saying the new train line "will add tremendous new transportation capacity" and allow riders to cross from Bellevue to Seattle in less than 20 minutes.

Voters approved the route as part of a 2008 ballot measure, and past agreements involving the federal and state governments envisioned mass transit on I-90.

Freeman hasn't decided whether to appeal, said Bruce Nurse, vice president and transportation aide for Kemper Development. He pointed out that Sound Transit has yet to prove it can operate unique "transition joints" where trains must move safely between the floating and fixed segments of the bridge.

Rail construction on the bridge is scheduled to begin in 2015, with the approximately $3 billion East Link extension from International District/Chinatown Station to Overlake Transit Center to open in March 2023.

Mike Lindblom: 206-515-5631 or mlindblom@seattletimes.com. On Twitter @mikelindblom.