what causes trains to derail
Some train wrecks occur when drivers exceed the posted speed limit (19 derailments last year), but, more often, the cars go off the rails because the brakes weren't used correctly. An object that happens to be sitting on the track isn't likely to derail an oncoming train. A freight train can typically throw a 4,000-pound car out of its way without getting off trackâalthough in 2005 an SUV left on a commuter track caused a fatal derailment in California.