A hazardous chemical in a rail car was the source of an explosion on a derailed US train that sparked a fire, rattled homes and damaged buildings, train operator CSX Transportation has reported.
A company spokesman said today officials weren’t sure what caused the sodium chlorate to explode, but it ignited another chemical in a second car.
In the third serious derailment in the US this month, a dozen or so rail cars went off the tracks Tuesday in a Baltimore suburb after colliding with a truck at a crossing. The fire was under control by Wednesday. Only one person — the garbage truck driver — was seriously injured.
Despite the recent accidents, US railroads were thought to be safer than ever. The number of train accidents fell 43 per cent to 1712 between 2003 and last year as railroads invest in their equipment and in technological tools to help detect problems.
‘‘Last year was the safest year on record for the railroad industry,’’ said Federal Railroad Administration spokesman Warren Flatau.
In Tuesday’s accident, CSX spokesman Gary Sease said the sodium chlorate in a derailed car near the front of the train exploded, igniting terephthalic acid in another derailed car.
Sodium chlorate is used mainly as a bleaching agent in paper production.
Oklahoma State University chemist Nick Materer said it could make for a potentially explosive mixture when combined with an incompatible substance such as spilled fuel.
Baltimore County’s Public Safety Department said hazardous materials experts did not believe the burning chemicals would produce toxic inhalants. But a National Institutes of Health website said oxidizers such as sodium chlorate may produce irritating, corrosive and/or toxic gases when burned.
Toxic inhalation hazards are a worry when trains carrying hazardous materials derail.
They include chemicals such as chlorine, which killed nine people after a derailment of a Norfolk Southern train caused a release of the toxic gas in South Carolina in 2005.
Robert Sumwalt, a member of the National Transportation Safety Board, said investigators were reviewing train video that might show Tuesday’s collision.
Sumwalt said the collision occurred at a private crossing where the only marking was a stop sign. He said it wasn’t clear whether the truck was authorised to be there.