3 ms·but what if the alarm isn't working when something is wrong?by wnevets 8y agobut what if the alarm isn't working when something is wrong?agumonkey 8y agoso same as train brakes in a waypaulie_a 8y agoTrains slow down and use the engine at a slower pace. You don't have a back up heart.agumonkey 8y agotheir braking system is passive, no energy means error means brakes engaged; unlike, say, cars where no energy means .. nothing and any accident can occur.paulie_a 8y agoHow are cars relevant? I was specifically pointing out trains.