Railroad train fires and munition explosions | The History of Insensitive Munitions

On April 28, 1973, over 6000 Mark-82 500 pound bombs detonated over 18 hrs in a railyard in northern California. 5500 structures were damaged, and the town of Antelope destroyed, with every building reduced to foundations. It leads to the Transportation Safety Act (1974). From the article:

"28 April 1973 a railroad accident focused national attention on the hazards of munitions involved in fires. A hot brake shoe ignited the oak-wood floor of a Department of Defense boxcar carrying 250 lb. (MK 81) Air Force General Purpose bombs filled with Tritonal (TNT/aluminum). These bombs were being transported from the Naval Ammunition Depot, Hawthorne, NV29 to the ship load-out port facility at the Naval Weapons Station, Concord, CA (Port Chicago).

The train had just entered the yard in Roseville, CA when a fire was observed coming from one of the boxcars. The fire department was summoned but before they could act, a large explosion demolished a boxcar and spread the fire. Over a period of approximately 32 hours, 18 boxcars exploded in succession. The railroad yard was essentially destroyed. Fortunately no one was killed; however 48 persons were injured. There was about 24 million dollars in property damage to the railroad yard and the surroundings. The litigation that followed lasted for several years and cost the government millions of dollars.



Ammunition train explosion, Roseville, CA. 28 April 1973
Following the Roseville train incident, the Department of Transportation, DOT, placed an embargo on the shipment of Navy munitions in the U.S. Persons at the DOT recalled that another train incident involving munitions had occurred on 29 June 1969 in Tobar, NV. There, three boxcars carrying Minol-2 (TNT/aluminum/ammonium nitrate) loaded 750 (M-117) pound bombs from the Cornhusker, NE Army Ammunition Plant had exploded leaving large craters in the rail bed.

Again, fortunately, there had been no fatalities in that accident and only two persons had been injured. Evidence along the tracks indicated that there had been a fire on the train before the explosion. There was no information on how the fire had started but a hot brake shoe was suspected. Some “self proclaimed” experts hired by the railroad proposed that both incidents were caused by a spontaneous ignition of the explosive in the bombs caused of an unspecified chemical instability.

The embargo on the shipment of munitions following the Roseville incident was lifted after two days. Fortunately, a person recording train sounds in the mountains outside of Roseville, CA had seen the train. He testified that he had seen a fire in the floor over the wheel of one of the boxcars in that train some six hours before the first explosion occurred in Roseville. With this information, the Navy convinced the DOT Transportation Safety Board and the Department of Defense Explosive Safety Board that its munitions were safe to transport as long as there were no fires on the transporting vehicles.

The investigation of the Roseville train explosions was continuing when there was another train explosion. Twelve boxcars loaded with 500-pound (MK-82) bombs loaded with Tritonal from the Naval Ammunition Depot, McAlester, OK. exploded near Benson, AZ. These munitions were also in transit to Port Chicago, CA for shipment to Vietnam. Twelve boxcars and 460 feet of railroad bed were destroyed but there were no casualties. As in the other railroad accidents, the evidence collected showed that a fire in one of the boxcars had caused of the accident.30"