Chicagoist recently made a long post about the photography rules on the CTA and how they are still convoluted.
Here’s my short and simple interpretation of the rules:
No tripods
No cables
No lights
No obstruct transit operations
No interfere with customers
No blocking doors
No blocking stairs
No blocking the flow of traffic at a station
No causing a distraction
No getting in the way of customers
No photos of tracks
No photos of storage rooms
No photos of work areas
No photos of end platforms
Yes photos of areas where you enter the station
Yes photos of where you pay your fare
Yes photos of where you wait for trains

With the exception of the “no tripods” and “no cables” rules, I’ve done every one of these things while using my camera in the New York subways. The CTA makes the MTA look like a bunch of pussycats.
I hear Leni Riefenstahl has unrestricted access to CTA.