On the vendors a couple corrections. The original fare gate equipment was in fact IBM who publicly said they deliberately low balled the bid to get the experience. (BART was seen as the precursor to widespread transit construction.) The computers for the ATC/ATO were sold to BART by Westinghouse which had never built anything similar. They bought actual computers from GE and relabeled them. As those of us who were here then remember, the train control was so dodgy that they operated by manual block when they opened--plywood boxes on the platforms w/train spotters using telephone lines to central.
It was an outsider who figured out that the arrival prediction hardware actually worked and could be used to tell central where trains were. With the hundreds of millions of $$ spent (including changing out the "servers" at least twice) they have never achieved the promised 90 second headways which CTA was capable of with "obsolete" wayside signal lights in the 50s. (They actually scheduled 118 seconds, still greater frequency than BART.)