Bill is correct, the CTC tunnels and junctions were 'made to measure'.
Email me so I know an address, I will send links for the CTC so you can see what I'm talking about and how we lined everything up. One thing we did differently, as we were modelling an 'all tunnel' prototype, the whole model was built on the top of flat boards. If after seeing that lot, if asked, I will send whatever Gmax files are selected. Although they are made for 2 ft gauge and a very tight tunnel clearance I think it would be possible to scale them up to suit standard gauge.
As an aside, the route assets would be perfect for an undergound mine.
Peter