I was just describing what could already be done mostly via software, and that would be easily transferrable (read: sellable) to other subway systems and places

I was just describing what could already be done mostly via software, and that would be easily transferrable (read: sellable) to other subway systems and places with mugging problems. The LAPD has a system that triangulates bullet shot sounds and dispatches police officers to the approximate location of the shot. This isn't that different.