Scans_Daily

Very true. The system I described is Centralized Train Control with Automatic Train Stop. CTC was introduced in the 1920s, and ATS in the early 1930s.

The automatic block signals used between switches were introduced in the late 1890s, IIRC, and locally-controlled interlockings at switches (as opposed to how CTC puts most of those under remote control by a centralized dispatcher) were introduced even before that. The NYC Subway has installed a large number of additional safety systems on top of their ABS/CTC and ATS (or equivalent--I can't recall if they use the actual ATS system or something slightly different in detail) systems, to further improve safety, over the decades.

So what I'm describing isn't really a big new high-tech control system that'd cost Gotham billions to install--it's the stuff that's been industry-standard for almost a century now. (Many mainline railroads don't use ATS, because it requires a cab signal system to transmit the signal aspects to the on-train hardware, but they don't have nearly the traffic density that a major urban transit system has, and thus can't justify the expense. Any place where trains run 80 mph or faster, or where passenger trains run with the kind of density you see on a subway system, is required by federal law to use ATS or equivalent and cab signals...)