Here we see what is called an "alerter" on a locomotive. It is designed to keep an engineer awake and in the seat. After a set amount of time and if there is no input of any kind, then the alerter activates. It starts out as just a flashing red light and progresses to a loud beeping. The longer is stays on, the louder and more intense it gets until the reset button is pressed or there is an input on the control stand.

If the alerter is ignored for too long then the emergency brakes are automatically applied and the entire train comes to a stop. There is a specific button on the control stand that resets the alerter but any input from the engineer also resets it, such as adjusting the throttle, applying brakes, or turning on the bell or whistle.

I do not work for the railroad in any way and this footage was given to me. I have more videos ready for release. Subscribe to stay in the loop!