Hello Andy!
I just responded to your trouble in the other thread. I like the idea of a light inside the tunnel, provided it doesn't give off too much heat.
I agree with you that it's best to have the bulk of a tunnel easily accessible, if not totally open, especially on long runs or leads to hidden staging.
One last thought for now about your trouble with loop #2; Be psychologically prepared to tear the entire trouble spot out. My experience tells me that if I didn't do it right the first time, I'll probably ALWAYS have trouble with that perticular spot.
Also, your roadbed could be fine, the alignment is correct, yet in laying, the track could have been bent or somehow damaged. Look into that possibility also.
All it takes is one stupid little thing to mess the job up!
Total replacement ultimately spares operating headaches, and you won't regret it.
George.
On my layout. The back of my tunnel is open. I did this in case of derailments. I also added a 12 volt light in there when I am working. It can be dark in the tunnel!
You can't see the opening from the main control area.