In 1941 the Army built the 48 mile long Claiborne and Polk between Leesville (Fort Polk) and Alexandria (Camp Claiborne) in Louisiana to train WW2 Railroad Operating Battalions. Much of the line was intentionally built over the very unstable mud of the Louisiana swamplands and had numerous wooden trestles. The intent was to train soldier/railroaders in the adverse conditions they might encounter in the war zones. Derailments didn't have to be staged, they ocurred naturally due to roadbed conditions, and trains were followed by a big hook and work train to see how fast the derailed engines and cars could be re-railed, and the track repaired and returned to operation. I recall reading an account of one run where the locomotive derailed five times and the big hook in the following wreck/work train another three times. Trestles would be intentionally blown up and work crews raced around the clock to rebuild them and reopen the road asap. Backshop forces were trained to repair locomotives and cars in very primitive conditions. IIRC the C&P rostered 7 engines, 4 ten wheelers and 2 concolidations. A few photos of the C&P can be found on Mike Palmeri's Louisiana Rail site.
Mark