It seems likely that alerters are not the whole answer to crews staying awake and alert. Forty years ago when I was a young brakeman on a certain western railroad that still ran a lot of F-units, there was an unwritten and essentially unspoken "rule" that the head brakeman (we had almost no firemen by then) could doze while underway and the engineer could do so while in the hole waiting for oncoming (or sometimes overtaking) traffic. Those were the days of the 16-hour law and during the summers, time off was often very limited.

I never fell asleep in the cab that I recall, though the drone of 567's at a steady throttle level sure tends to make you want to nod off. But I worked occasionally with an engineer who was known for going to sleep at 50 mph and staying that way. I would have to stand up and whistle for crossings, but the airhorn's blasting would only cause that hoghead to straighten up for a few seconds. When past the crossing he was right back asleep. Would an alerter do any good with someone who can sleep like that?