Office of Railroad, Pipeline and Hazardous Materials Safety

DOT-111 Tank Car Design

Paul L. Stancil, CHMM

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Previous Investigations

• 1991 Safety Study

• 1992 Superior, Wisconsin

• 2003 Tamaroa, Illinois

• 2006 New Brighton, Pennsylvania

• High incidence of tank failure

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Need for Better Tank Cars

• 69% of tank cars are DOT-111

• Transports wide spectrum of hazmat commodities

• 40,000 DOT-111’s used to transport denatured fuel ethanol

• Ethanol is the most frequently transported hazardous material

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Tank Heads and Shells

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Top Fittings Protection

• DOT-111 housings not effective in preventing impact damage

Post Accident AAR Actions

• All new DOT-111 for ethanol and crude oil service beginning October 1, 2011:

– Increase head and shell thickness – Normalized steel – 1⁄2-inch thick head shield – Top fitting protection

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Hazmat Unit Train Operations

• Certain hazardous materials are transported by unit train

• Virtual pipeline

• Risks are greater because of high concentration of hazardous materials

• Increasing number of unit train shipments

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Existing Tank Cars Not Addressed

• AAR actions do not address existing fleet

• Impediments to retrofitting or phase out

• Long service life

• Safety benefits not realized if old and new tank cars are commingled

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DOT-111 Design Inadequacies

• Tank head and shell puncture resistance systems and increased materials thickness may have reduced the severity of the accident

• Housings for protection of DOT-111 top fittings are inadequate to withstand the forces of a derailment