Originally Posted by
cloudybw
CHI. Can I walk to the train at CHI?
Most certainly not; CHI is a prime example of tightly-controlled platform access for passengers only. You could ask about special arrangements when accompanying them to check in at the Metropolitan Lounge (for sleeping car pax). The attendant will most likely recommend that your parents request Red Cap assistance to pre-board, admonishing you to not follow them when they're called to board.
Back in the day (mainly pre-9/11), many conductors used to make a warning announcement at major stations for "visitors and baggage helpers" to detrain. I haven't heard that announcement in many, many years because it is now assumed that only ticketed pax would be aboard.