bayarearapidtransit

The DO NOT BOARD sign in 1974 identifies destination. In recent years, number of cars in the consist have been added. Example:

RICHMOND 7 CAR TRAIN APPROACHING
FREMONT 9 CAR TRAIN 6 MIN

I believe the signs shown here were incandescent light bulb arrays. There's a standardized yellow color used in modern signage because it's supposed to work best with the broadest range of low-vision humans. Modern signs look like the 400+ NIT daylight viewable LED arrays but I don't know if that's what they're using.

A matching audio announcement goes over the station loudspeaker system. In the 2020s, announcements are generated by some kind of voice synthesizer. Stations have almost entirely hard surfaces which reflect the announcements making intelliigibility vary depending on where you stand with respect to speaker locations.

Train horn is some kind of electronic 400-cycle tone.

You might call it the golden escalator. Or not.

People are looking at newspapers instead of smart phones. There are no video surveillance cameras, or phony video cameras, in the cars back in 1974.