Nostalgic tug here; for the D terminals they were MUCH faster than the interminable walk + trains and 2 (or 3?) + escalators + moving walkways to the other terminals.
Farewell to the legendary Dulles People Mover (1962–2026)
Was it a bus? Was it a train? Nobody knew
Thankfully, your service will no longer be needed 🫡✈️