A BNSF Railway derailment Feb. 16 was caused by a broken wheel, BNSF reported to the Federal Railroad Administration.

The broken wheel caused 40 (out of 121) loaded coal cars to derail from the train tracks about four miles west of Cloquet three months ago. Cleanup started almost immediately. The derailment dumped more than 4,000 tons of coal near or partially into the frozen St. Louis River.

“BNSF conducts a thorough review of every incident because we want to understand what happened and why, and work to prevent it from happening in the future,” BNSF spokesperson Amy McBeth told the P...