What if all roads have to be built as routes? As in, they need a solid start and end point, like city to city, or city to resource?
I was originally against the idea of getting rid of the roads, but this makes the most sense. Although I do like building roads towards my enemies for attack, it doesn't really make sense in the universe you have roads in every single square, most of which don't actually go anywhere. So if you wanted a railway to your enemy you can negotiate a trade treaty, or build a military fortress on the border.