Trains have a belt and suspenders approach to safety and FRED would go nuts if separated from the locomotive. https://en.wikipedia.org/wiki/End-of-train_device

Trains have a belt and suspenders approach to safety and FRED would go nuts if separated from the locomotive. https://en.wikipedia.org/wiki/End-of-train_device https://en.wikipedia.org/wiki/End-of-train_device Also very few non-railroad people understand pneumatic safety brakes, and suddenly breaking a brake hose locks the breaks on both halves of the train until the tanks drain completely down. Pneumatic brakes operate like a mechanical differentiation analog computer and the strength of the brake application is the rate or slope at which the brake hose pressure is dropping. An axle counter is like the stupidest defect detector imaginable. Modern defect detectors are like robot Q+A inspectors, every 20 miles or so they detect hot bearings, any load hanging out or down or too high, fancy ones can do on the fly weighing (hmm that tank car full of oil is losing 50 pounds per mile, someone has a leak...) for decades there's been work done with various barcode and RFID schemes to track and log individual cars, pretty interesting stuff. I would guess there exist dumb defect detectors that can not detect overheated bearings at exact integer multiples of 1024 degrees F or something. There's a nice one near a park a few miles from my house and using a scanner tuned to railroad frequencies you could hear a synthesized voice identify itself and say something like "no defects found" I never heard it say anything else. There is nothing wrong with defense in depth. It was paid for in blood, after all. The biggest problem with defense in depth is it leads to lazyness, well, we don't have to care about 256 axle trains because there's at least three other safety systems, etc etc. Then you end up with every one of them in a corner case and someone gets killed resulting in more regulation.