DOT Proposes Puncture-Resistant Hazmat Tank Cars

A new U.S. Department of Transportation proposal requires tank cars carrying Poison Inhalation Hazard (PIH) commodities such as chlorine and anhydrous ammonia to be equipped with puncture-resistance protection strong enough to prevent penetration at speeds of 25 mph for side impacts and 30 mph for head-on collisions—more than double the speed for existing tank cars.

"This proposal is designed to significantly reduce the hazard of hauling hazardous materials by rail," said Mary E. Peters, secretary of transportation, explaining the performance-based standard will increase by 500 percent on average the amount of energy the tank car must absorb during a train accident before a catastrophic failure may occur.

The proposal allows flexibility in reaching that goal, but it is expected that the outer tank car shell and both head ends will be strengthened, the inner tank holding the hazmat cargo will be better shielded, and the space between the two will be designed with more energy absorption and protection capabilities.

The proposed rule also sets a maximum speed limit of 50 mph for any train transporting a PIH tank car. In addition, a temporary speed restriction of 30 mph is being proposed for all PIH tank cars not meeting the puncture-resistance standard and which are traveling in "dark," or non-signaled territory, until the rule is fully implemented or other safety measures are installed.

Finally, the proposed rule requires that some of the oldest PIH tank cars be phased out on an accelerated schedule. Specifically, this addresses the concern that PIH tank cars manufactured prior to 1989 with non-normalized steel may not adequately resist the development of fractures that can lead to a catastrophic failure.

This proposal was developed by the department's Pipeline and Hazardous Materials Safety Administration in close consultation with the Federal Railroad Administration and addresses issues arising from serious train accidents involving hazmat releases that occurred in Minot, N.D., Macdona, Texas, and Graniteville, S.C.