WMATA Train Operating modes

How to tell if the metrorail train is under automatic or manual mode?

look in cab and see if T/O's hand is on the controller

If the train comes smoothly to a stop, it's probably not under manual control (although they're getting better!).

Also, 6 car trains stopping at the end of the platform where they usually stop in the middle is a dead giveaway.

How to tell if the metrorail train is under automatic or manual mode?

It used to be the case, and I assume still is, that the ATP overspeed alarm ( beep-beep-beep...) sounds only in manual operation, telling the operator he or she must go to brake in a few seconds or suffer a penalty stop. So if you are sitting in the first car and hear it, the train is in manual.

Additionally, in automatic mode, the operator often times still has his or her head out the window when the brakes release and the train starts to move again...