I think railways would be a very fast and nice way of transporting stuff, constructing roads with the terrain tool is fun but sometimes it can be tedious at large distances, and the roads have to be perfectly flat to avoid doing air flips while driving, however, railways could attach the vehicles to the ground and allow a faster and smoother ride! it'd be very fun to be able to construct a railway connecting certain places like player bases or specific landmarks, or a whole network of underground railway paths heading into deep mines! I've tried with roads and trucks but it's difficult to move around that way ( I flip backwards while trying to get back to the surface, I'm a terrible driver ).
The tracks could be ideal to place big truck caravans on them! as the one in the screenshot ( Not taken by me).
It'd optimize resourse gatheting and help to travel around the planets, it adds up on the industrial feeling! I hope you like the idea, thank you very much for reading~