TUNNELS

[Sunny]

Why won't the game make a tunnel through a mountain?
Every time I try to build a tunnel through a mountain it either builds over the mountain or it cuts through leaving an ugly eye sore with the mountain missing where the road was built.

does any one have a solution to this?

[Sylvaa]

I use the variable road setting, place a point just before you move from flat to slope, then place a second point 5 metres deep, into the slope, then another 10m deep, ensuring it looks sort-of-flat then the same in reverse, the other side, until back on flat open. You get a gentle slope in, and a gentle slope out, with reasonably tidy entrance and exit points. I do the same with trains and it seems to work OK.

It's going under rivers and lakes, that I find awkward.

[mikelleh63]

The default is the road follows the contours of the land, even underground, so you end up with wonky tunnels. Get your road underground at entry point and another one at the other end at a consistent depth. Then, on road tool make sure at bottom that tunnel mode is selected and also select the constant slope setting. Then stretch one long tunnel road between the 2 points. Nice level tunnel every time.

[sternenstaub70]

Originally posted by mikelleh63:

Then, on road tool make sure at bottom that tunnel mode is selected and also select the constant slope setting. Then stretch one long tunnel road between the 2 points. Nice level tunnel every time.

That's a feature from the Anarchy Mod.
Without Anarchy, you don't have this option.
It seems, OP has not Anarchy installed.