The one thing that bothers me in this game, is that there are no hotbox detectors (that I've found yet). I don't know if all railways use them, but there's almost 1 for every 2 sidings in the region where I work. I feel like it would be a rather easy feature to implement
Functioning ones would be. When a hot box is detected it triggers an alarm in signal boxes/signalling centres and then it's up to the signaller on duty to take action which is stopping the train, getting the driver to examine and if deemed necessary proceeding at a much reduced speed. That's a hell of a lot of stuff to implement!
There are a lot of realism features that I wish they'd implement. And if they won't implement them, give us the programming ability within the route/scenario editor to do it on our own. Hotbox detectors Catenary dead sections/phase breaks Wheel impact detectors
I suggested this to DTG as well, and I know with UE4 it is possible to make them work. It definitely would add more realism.