ROSEDALE, Md. -- Train operator CSX Transportation yesterday pointed to a hazardous chemical in a rail car as the source of an explosion on a derailed train near Baltimore that sparked a fire, rattled homes and damaged buildings.
A company spokesman said officials still weren't sure what caused the sodium chlorate to explode, but it ignited another chemical in a second car.
Authorities are continuing to look into the cause of Tuesday's incident. Robert Sumwalt, a member of the National Transportation Safety Board, said investigators were examining evidence on the scene and reviewing train video that might show the collision with a garbage truck that set off the incident.
Sumwalt said at a news conference yesterday that the freight train was traveling 49 mph and that the engineer blew a whistle three times before it collided with the truck.
The train hit the truck as it was crossing the tracks around 2 p.m. Tuesday, Sumwalt said. He added that the locomotive applied its emergency brakes and traveled nearly a mile before coming to a stop. Fifteen of its 45 cars derailed, including three of the four cars that were carrying hazardous materials.
The chemical that exploded was sodium chlorate, which is highly volatile. Sumwalt said the explosion, which damaged nearby buildings and shook homes miles away, occurred 5 minutes and 23 seconds after the initial collision. The sodium chlorate was in powder form and was being hauled in a covered hopper car.
CSX spokesman Gary Sease said the sodium chlorate in a derailed car 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.
The railroad said in a news release yesterday that it continues to work with state and federal environmental officials to "clean up products released in the derailment." The company said it is conducting air, water and soil sampling and sharing that information with officials.