Problems with Monorail tunnel

[VeritechCEO]

I'm trying to lay a monorail tunnel into a mountain side but it seems that no matter what I do, a small porsion of the mountain side shows inside the tunnel. I've tried raising the terrain to fix this but the terrain seems to auto fix itself to what it was before I tried. Any suggestions?

 

[tongs]

I am running TS09 and I have had similar problems with all tunnels unless I raise the ground over the tunnel entrance portals and extend the raised bit at least 50% across the portal top (roof?). Hope this helps