Last year's disastrous Norfolk Southern train derailment in East Palestine, Ohio, was caused by a wheel bearing that video showed was on fire for more than 20 miles (32.19 kilometers) beforehand but was never caught by trackside detectors that failed to accurately measure the temperatures, the National Transportation Safety Board confirmed Tuesday. The board also said that Norfolk Southern and its contractors botched a decision three days later to blow open five tank cars and burn the vinyl chloride inside.