Nonetheless, it is what is used on freight lines in the U.S quite successfully, and provides other protections such as broken rail detection. Detached cars are

Nonetheless, it is what is used on freight lines in the U.S quite successfully, and provides other protections such as broken rail detection. Detached cars are detected using the FRED/braking system, and secondarily by axle counts given by hot box detectors read over the radio.