Rail cars hauling crude oil have had a bumpy ride over the past few years. From Quebec to Virginia, the extreme forces of crude-laden tank car collisions in recent years have split steel like an orange rind. On Monday, another milelong CSX Corp. oil train derailed and caught fire near Montgomery, W.Va., destroying a home and forcing hundreds of people to evacuate. But more often than not, damaged rail cars don't cause a disaster. And sometimes those damaged cars are attached to the end of another long oil train heading in the same direction.