Well, when I say I ride "frequently" I mean only several times a month, not daily. Maybe we HAVE run into each other, but I don't think you would recognize me.
BART was the most technologically advanced urban rail network when completed:
It sported brand new digital displays and pressure sensitive escalators in stations (that didn't start until you step on them).
Trains travel at up to 80 miles per hour on underground legs.
The system has 95 miles of track.
39 BART stations comprise 12 surface, 13 aerial and 14 subway stations. Four of these are a combination of BART and MUNI Metro stations in downtown San Francisco.
The total cost of the system (excluding Transbay Tube) was $US1,443,000,000. The cost of the Transbay Tube (which links SF with the town of Oakland) was $176,000,000.