A broken rail caused 21 freight cars to jump the tracks this week in the City of Industry, a Union Pacific official said Wednesday, as Metrolink passenger service to Riverside resumed on the repaired rail line.
Metallurgical failure is "not unusual" on train tracks, but routine inspections normally detect flaws before accidents occur, said Union Pacific spokesman John Bromley. He cited age and stress as the most likely reasons for Tuesday's break.
"The rails flex up and down as a train passes over," Bromley said. "They can break, like a paper clip."
Wednesday evening, several cars from another Union Pacific freight train uncoupled from a locomotive, derailed and came to rest against a warehouse in Santa Fe Springs, Whittier police said. They said the accident occurred on a spur line and did not disrupt Metrolink service. There were no injuries, and the cause of the uncoupling wasn't known.
Officials said the Federal Railroad Administration and possibly the California Public Utilities Commission will investigate Tuesday's crash.
The tracks in Industry, owned by Union Pacific, are shared by Metrolink commuter trains. Tuesday morning's derailment interrupted service until about 4:15 p.m. Wednesday. Shortly before the derailment, commuter trains had passed without incident over the section of track that later failed, near Fullerton Road and Railroad Street. Bromley said passenger trains weigh much less than freight trains and could have easily passed over a rail that could not withstand the stress from the 48-car Union Pacific freight line that jumped the tracks.