Hi. The fact that this possibility has been in the game for a while doesn't make it any more correct, and it st no plausible justification.
If a rail network is destroyed, it is only logical that both own and enemies using the rail network cannot use it anymore. It cannot be that orders given before the destruction can dig the whole thing out and ignore the destruction.
This possibility should be removed from the game.
Why are own rail guns stopped in a province if the rail network (railroad) is destroyed, while enemy rail guns without a rail network can leave the province and thus are not affected? Where is the sense in that?
I conquered the province, the rail network was completely destroyed, in the entire province. My rail gun can't move a millimeter, but the enemy's can? Does the enemy train float through the air, or how am I supposed to understand this logic?
And it doesn't matter if the order to move was given before the destruction. If a rail network is shot down, I expect the trains to stop and not miraculously move on. This makes no sense at all and destroys the immersion.
My rail guns also got the order to move beforehand. Stopped they were automatically, while the opposing player is leisurely driving through the world history without rails, with railroads.... So either you create rules that apply equally to all players, or you eliminate railroading altogether as a prerequisite for rail guns to move!! 
