Imagine, it’s a shivery January morning in 2014 and you are riding one of the first of Metro’s Silver Line cars to Tysons Corner. After you step aboard downtown, the train runs west out of the District and into Arlington County. It passes through the East Falls Church station, just as the Orange Line does, but then hangs a right away from the Dulles Toll Road and soars onto newly built tracks 50 feet in the air.