During the week, the D.C. metro runs until just after midnight (it runs until 3 AM on the weekend). I always wondered how they coordinated transfers between “last trains” of the night, and last night I found out. I managed to just barely make the last Orange Line train in the direction of New Carrollton. When I got to L’Enfant, I discovered just how the process works. It goes something like this:
You don’t want people on the Yellow or Green lines transferring to the Orange line because the last Orange line train has already come through. So the last Green Line trains of the night come into the station empty. In fact, L’Enfant is their starting point in both directions. They wait until the last Orange and Blue line trains have come into the station. This gives passengers on those trains a chance to board. (Since the Green line trains were empty coming into the station, there is no one left to transfer to Blue/Orange line trains.) Once everyone has boarded, they depart for their final destination.
It’s clever and I wouldn’t have thought of it unless I had seen it myself.