Bumping to ask if there are any recent experiences to report re: Union Station departures. I have a 700a Saturday morning departure on Amtrak to Springfield and have never done this before. I've scoped out the Great Hall and the central kiosk, but did not see anyone lining up for anything.

Do they form up groups A-B-C-etc. in the Great Hall, then lead those groups down to the track one at a time, like grade-school field-trippers? And is it really advisable to get there 45m before train time?

EDIT to answer my own question, as I've now been through the experience:

The Great Hall boarding queue process is in effect only between 1200p and 800p, when things are busy. Mornings are quiet and all the confusing boarding advice on the Amtrak website, etc. is inoperative. You just go downstairs, use a Quik-Track kiosk to print off BPs if you need them or call up your e-BP on your phone if you'd rather, and show same to get access to the track-proximate boarding lounge.

It is absurd to get there 45 to 60 minutes before train time as Amtrak advises. 30 minutes prior is plenty. We could have slept longer.

Boarding is called about 20 minutes before train time (those in the know get up and form a queue at the appropriate gate before that), and cut off at five minutes before departure.

It's far simpler than Amtrak makes it out to be, at least in the mornings and evenings.