I had a train tunnel, and I decided to (temporarily) remove it, and then put it back. But I did so by removing only the tunnel at the exits on both ends, not the bit in the middle which is undergroudn and not visible. When you do that, you cannot replace the tunnel. When I try, I get an error message: "Tunnels must start on a single way", or sometimes "tunnels must start on a straight slope". When you remove all the tunnel along the entire tunnel length at once, there is no problem. (Obviously, the slopes are fine, I just had a tunnel there a minute ago, and did not mess with the terrain).
I've reproduced this in 3 different maps, both for long and short tunnels, with and without raising/lowering lands (making the length of the tunnel I want to build longer/shorter).
I'm playing 111.0, pak128 2.0.0.
I hope I'm not reporting something that's already known. I had a look and couldn't find this yet. Thought someone might want to fix it (hopefully it's easy!).
Press "u" (or "U", can't recall exactly) to go into underground mode. There you can remove your tunnel or build a complex structure under the ground including stations, etc. :) Also, if you want to add an entrance to the underground that is not supposed to end up straight on the other side, you can start your tunnel with holding the "ctrl" key and then finish the structure in the mentioned underground mode. I hope I was helpful.
Ah, that's a revelation, to say the least :)
Thanks for the quick reply.
Still, for newbies, the error message could perhaps give a hint about the underground mode? I hadn't really discovered it yet, and it would have prevented a lot of frustration!
That is a good hint for the english translators on simutranslator.