Working strictly from memory, since I first read this (in Trains or Railroad) a half-century or more ago.
Scenario: Grande passenger train, 4-8-4 power, running eastbound (downgrade) from Tennessee Pass at night in a ground blizzard, temperature 'way below zero.
At an acute-angle grade crossing, the ice in the flangeways (which must have been as hard as armor plate) lifted the flanges, derailed the locomotive parallel to the road centerline and on the road. The engineer didn't realize that he was no longer on the rails until a signal failed to appear. At that point he had run about a mile down the ruts of the hard-frozen dirt road.
No injuries, no damage to the equipment - but I'll bet getting that train back on the rails was a bear.