That is an excellent list of tunnel assets. Most of what I use is there already. There are some considerations: The tunnel you select should be tall enough for catenary wires if you use them. In case of UK tunel, it is too low for European wires perhaps due to different loading gauges?. It is because it has a piece of track built in. Other tunnels don't allow adjusting the height, leaving you with moving the terrain up or down (do this before applying the dig tool). Note that after importing to T:ane, for some reason, I think is a bug, the height will be all screwed up, and you will have to fiddle with a lot of things to return to what was "perfect" in last versions. And finally, there should be a more descriptive selection of the type of spline to use with that particular portal (some do, some is up to you to try and find). A suggestion for creators: What about a cliff spline with the cut out for portals? as it is now you have to use a combination of several, rocks, vegetation and use your inventive and imagination to cover the hole. If you are like me, I still had the old clumsy tunnel portals from years ago waiting for replacement. You transport your route to T:ane, and all those tunnels are gone! and they are fixed to the grid using at least two squares. Now you install the new smaller tunnel and it uses normally one square. So you have to move the entrance to one side to occupy just that one square. But if your tunnel is in a steep cliff, coast line or other place, it may not be convenient, then you have to cover the two holes with splines and all that. Hence a premade object with the cutouts would be nice. Have to mention that T:ane has a selection of portals with quite a few nice built in terrains that are very well made, even if some of them look as if they come of a mine of diamonds!
Overall, this tunnel chapter gives you an opportunity to act on your abilities and inventiveness.
