> in CR, the engines were more like cars, they didnt need rails to drive.
> imo its a bit too unrealistic

No, it's not. Steam-powered road vehicles actually exist in reality.

> What about rails for engines? i got this idea when i thought about to model a railroad station.

Let me chime in with my experiences from my (discontinued) Wild West train project.
The Wild West train featured a big steam locomotive, which was a lot faster than the traditional steam engine, was able to pull more than one waggon, and needed rails to drive on.
The rails worked similar to the bridge segments, with two differences: 1) They had no solid mask, so they were no obstacle for Clonks and other vehicles, and 2) it was possible to rotate them, so that a train was able to climb slopes.

The pros:

• Rails allow trains to pass mine entrances and elevators without falling down the shaft. And since they have no solid mask, the shaft remains accessible for Clonks.


• As the locomotive stops driving when not on rails, trains only drive exactly where you want them to. That a train takes "the wrong turn" and is lost (e.g. by falling off a cliff) doesn't happen. At least not unless your railway happens to have a dead end exacly there.

The cons:

• On the other hand, building a railway from A to B is tiresome: Even though the rail segments were relatively wide, building a whole way piece by piece takes a lot of time. This is a very repetitive and unchallenging task, and as such, not much fun. (This also applies when the rails are built similar to loam bridges.)


• You can't simply board your train and explore unknown territory. This makes the locomotive relatively unattractive in the early game, and degrades the trains to supporting you "in the background"* later on. You can't take your shiny new train with you on your exploration trip, or it slows you down severely, in the case that you carry rail segments with you.
  *support in the background would, for example, be bringing you new supplies to your mine and taking minerals you mined with it back to your main base. While automating that task already is a great help, using steam trains for that is really a waste. A simpler pneumatic tubes-style system could handle that, trains have a lot more potential.

In summary, I suggest not making rails mandatory. Instead, perhaps they could be a means of bridging gaps (like elevator shafts) only where necessary. Driving on rails might have a higher priority than driving on ground: When there is a railway slip road ("Schienen-Auffahrt"), a steam engine would start driving on rails, but drive on ground where no railway is available. I also highly recommend not giving the rails solid masks. Being able to pass through them makes them a lot more useful.