[Gwent rail]

Never made a curved bridge Neil, but I need to for the new layout I'm just starting. I had intended to make a shell out of flexi MDF and cover it with Slaters molded sheets. Another idea was to cover with stone sheets from International Models ( www.internationalmodels.net ) as I find their products amongst the best and you can get a flexible sheet from them ( molded polystyrene ) which is very good. Using this, only a framework would be needed. Anyway, the best of luck. Sounds like a project that would be interesting if posted to a new "builders corner" forum, if our esteemed moderators take notice of recent posts and start one!
Keep us posted on progress!