The Downtown Seattle Transit Tunnel, the only place in the world where buses and trains share an underground transit corridor, is a busy place during rush hour, with commuters crowding the platforms to board buses bound for all directions and light rail trains heading south. On this summer afternoon at Pioneer Square Station, an airport-bound Link train takes on passengers at the southbound platform while the northbound platform plays host to buses on King County Metro route 41 and Sound Transit route 550. The buses are scheduled to be relocated to surface streets upon the opening of the University Link extension in late 2016, and the 550 itself is due to be replaced by East Link light rail service in 2020.
