This has recently changed.
Express (which you need a 101 ticket from Hagrid's or Velicoaster for) now goes through Single Rider Line, where a TM will redirect you through stairs into the "Gloves" room merge point (same as it was when you came in through the exit). This staircase was sometimes used as the "re-ride" line in Dragon Challenge.
Single Rider still comes in down a different staircase, and ends up at the "Motorbikes on top", last, room.