03-08-2011, 10:16 AM
When I first read this post, I had no idea what would cause your problems. I'm wondering now if the underlying bench work is drying out and shrinking over time. I suspect cutting gaps in the rails might allow them room to straighten out and absorb the shrinking forces. You would need to solder new drops to each section of layout that is isolated by the gaps, but you would not need to put in any styrene filler because you are not adding new "blocks" to the railroad. Don't forget to cut gaps at both ends of the tunnel, and perhaps to the opposite end of the bridge.