Out of curiosity does the guard do this 1.25 mile run and back, before or after he has evacuated you .... as this little jaunt is going to take over 10 minutes even if extremely fit ... by which time you would be dead if he ran first, and good chance the train would have already hit you if he evacuated the passengers first
The protection can be placed down before the stated one and a quarter miles if the approaching train encounters the guard before the stated distance.
This would result in the detonators going off and the emergency breaks been activated on the approaching train, a train can do an emergency stop in roughly 30 seconds.
The safest place for passangers if the train has derailed is on the train until all surrounding traffic has been stopped, the guard would also ask any competent persons on board like an off duty police officer, guard, fireman or ambulance worker to assist in assistance with passangers on the train whilst they are doing the emergency assistance.
I don't expect you or any other passenger to understand what guards have to learn on the 12 weeks course, I wondered what the point of a guard was when I travelled as a passager for many years, just a ticket/doors monkey.
Now, working in the industry, I realise just how much they have to do, I shall not carry on with this as other postees will get sick of it, all I can say is don't criticise things that you don't understand, I don't know how to do your job so I couldn't tell you wether you were needed or not, the same applies to people who don't understand the role of guards/drivers.