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On October 22, 2009, about 10:38 a.m. eastern daylight time, a 2006 Navistar International truck-tractor in combination with a 1994 Mississippi Tank Company MC331 specification cargo tank semitrailer (the combination unit), operated by AmeriGas Propane, L.P., and laden with 9,001 gallons of liquefied petroleum gas, rolled over on a connection ramp after exiting Interstate 69 (I-69) southbound to proceed south on Interstate 465 (I-465), about 10 miles northeast of downtown Indianapolis, Indiana. The truck driver was negotiating a left curve in the right lane on the connection ramp, which consisted of two southbound lanes, when the combination unit began to encroach upon the left lane, occupied by a 2007 Volvo S40 passenger car. The truck driver responded to the Volvo’s presence in the left lane by oversteering clockwise, causing the combination unit to veer to the right and travel onto the paved right shoulder. Moments later, the truck driver steered counterclockwise to redirect and return the combination unit from the right shoulder to the right lane. The truck driver’s excessive, rapid, evasive steering maneuver triggered a sequence of events that caused the cargo tank semitrailer to roll over, decouple from the truck-tractor, penetrate a steel W-beam guardrail, and collide with a bridge footing and concrete pier column supporting the southbound I-465 overpass. The collision entirely displaced the outside bridge pier column from its footing and resulted in a breach at the front of the cargo tank that allowed the liquefied petroleum gas to escape, form a vapor cloud, and ignite. The truck-tractor came to rest on its right side south of the I-465 overpasses, and the decoupled cargo tank semitrailer came to rest on its left side, near the bridge footing supporting the southbound I-465 overpass. The truck driver and the Volvo driver sustained serious injuries in the accident and postaccident fire, and three occupants of passenger vehicles traveling on I-465 received minor injuries from the postaccident fire. The National Transportation Safety Board (NTSB) determined that the probable cause of this accident was the excessive, rapid, evasive steering maneuver that the truck driver executed after the combination unit began to encroach upon the occupied left lane. Contributing to the rollover was the driver’s quickly steering the combination unit from the right shoulder to the right lane, the reduced cross slope of the paved right shoulder, and the susceptibility of the combination unit to rollover because of its high center of gravity. Mitigating the severity of the accident was the bridge design, including the elements of continuity and redundancy, which prevented the structure from collapsing. A basic requirement for evaluating the accident performance of U.S. Department of Transportation (DOT) specification cargo tanks (such as the MC331 involved in this accident) is access to data that can be used to quantify both the involvement of those tanks in reportable incidents and the in-service population of those same tanks. While the approximate number of DOT specification cargo tanks involved in accidents may be obtained from the Hazardous Materials Information System or other databases, there is limited access to accurate information on the population of cargo tanks by DOT specification. For example, the most precise number of petroleum-hauling DOT 406 cargo tank semitrailers cited in the Cargo Tank Roll Stability Study2 appeared to be somewhere between 10,648–60,003 units. When asked at the August 2010 NTSB public hearing, a Pipeline and Hazardous Materials Safety Administration (PHMSA) official acknowledged that the agency did not know the total number of cargo tanks by DOT specification that were currently in service.3 Further, PHMSA indicated that data analyses for evaluating the performance of DOT specification cargo tanks could be enhanced if the population of cargo tanks by DOT specification were available. The NTSB concludes that the absence of a requirement for motor carriers to periodically provide the number of cargo tanks by DOT specification limits the ability to perform accurate trend analyses. The limited information currently available for PHMSA to quantify the distribution of cargo tanks by DOT specification differs considerably, for example, from information that can be accessed by the Association of American Railroads (AAR) about tank cars used for transporting bulk liquids by rail. The AAR has used the Universal Machine Language Equipment Register (UMLER) equipment management information system as the industry’s central repository for registered railroad and intermodal equipment since 1968. The UMLER system is updated in real time and capable of tracking equipment status, ownership, and inspection history and providing the particular fleet profile.
TO THE PIPELINE AND HAZARDOUS MATERIALS SAFETY ADMINISTRATION: Conduct a comprehensive analysis of all available accident data on U.S. Department of Transportation specification cargo tanks to identify cargo tank designs and the associated dynamic forces that pose a higher risk of failure and release of hazardous materials in accidents. Once such cargo tanks have been identified, study the dynamic forces acting on susceptible structures under varying accident conditions and develop performance standards to eliminate or mitigate these risks.
Original recommendation transmittal letter:
Open - Acceptable Response
Indianapolis, IN, United States
Rollover of a Truck-Tractor and Cargo Tank Semitrailer Carrying Liquified Petroleum Gas and Subsequent Fire
Addressee(s) and Addressee Status:
PHMSA (Open - Acceptable Response)
Safety Recommendation History
We note that the National Transportation Systems Center (Volpe) recently completed its analysis of cargo tank accident data and that you will soon be reviewing its report. We look forward to receiving periodic updates on your progress toward developing the recommended performance standards and compliance requirement. Until such actions are complete, Safety Recommendations H-11-5 and -6 are classified OPEN—ACCEPTABLE RESPONSE.
-From Howard W. McMillan, Acting Deputy Administrator: Since the last update, Volpe, The National Transportation Systems Center (Volpe)1 completed on behalf of PHMSA its analysis of 93 cargo tank rollover case studies occurring between 2011 and 2014 under PHMSA's Cargo Tank Incident Study. The study observed various elements of each rollover, focusing on potential human factors associated with each crash. Volpe reported the comparison between rollovers from about 10 years ago to those analyzed in this study and further examined the relationship among training regulations, training curricula, training technology, and advanced safety technology. Volpe used literature reviews, crash analyses, subject matter experts, and stakeholder consultation to inform its research. Volpe recently briefed PHMSA on the study' s findings and plans to submit a draft report to PHMSA by May 2017. PHMSA will continue to provide NTSB with updates on the progress of the Cargo Tank Incident Study and other analyses related to DOT specification cargo tank performance.
We support your continued comprehensive analysis of cargo tank rollover accidents and your efforts to ensure collection of complete and accurate data. Pending completion of these projects and the development and implementation of the recommended standards, Safety Recommendations H-11-5 and -6 are classified OPEN—ACCEPTABLE RESPONSE.
-From Cynthia L. Quarterman, Administrator: As PHMSA continues to work to ensure that existing and incoming incident data are complete and accurate, we are confident we can use the data to conduct a comprehensive analysis of specification DOT cargo tank motor vehicles to identify those that pose a higher risk. To realize a more complete analysis, on October 1, 2012, PHMSA initiated a 6-month special study to improve the data quality on cargo tank rollover incidents that occur after the study start date. PHMSA will review the 5800.1 forms submitted to us during this time period to ensure quality of data, and will follow-up with the person submitting the form regarding incomplete information (i.e., missing data) and to request additional information. The study will provide supplemental information (copy enclosed) to include: the configuration of the cargo tank motor vehicle (e.g., truck and semi-trailer); the cargo tank type (e.g. , circular); the vehicle gross weight; the degree and direction of rollover; the rollover protection device(s); and the specifics of damage to a tank shell (e.g., length of the dent). PHMSA will continue to provide the NTSB with periodic updates including progress on the special study and any further actions in response to Safety Recommendation H-11-5, and subsequently Safety Recommendation H-11-6.
The NTSB is aware that PHMSA sponsors the Hazardous Materials Cooperative Research Program (HMCRP) that is managed by the National Academies, acting through the Transportation Research Board (TRB). Further, we understand that an ongoing HMCRP project, HM-07 Accident Performance Data of Bulk Packages Used for Hazardous Materials Transportation, expected to be completed by late spring 2012, will help PHMSA address these recommendations. The expected outcome of the research is the following: • Recommend methodologies for collecting and analyzing performance data for U.S. DOT-specified hazardous materials bulk packages, such as portable tanks and cargo tank motor vehicles. • Identify and evaluate institutional barriers to data collection and recommendations for overcoming these barriers. Accordingly, Safety Recommendations H-11-5 and -6 are classified OPEN—ACCEPTABLE RESPONSE, pending completion of the project and the development and implementation of the recommended standards.
-From Cynthia L. Quarterman, Administrator: PHMSA shares NTSB’s goal of identifying cargo tank designs that pose a higher risk of failure and the potential release of hazardous materials in an accident. PHMSA is the sponsor of the Hazardous Materials Cooperative Research Program (HMCRP) that is managed by the National Academies acting through the Transportation Research Board (TRB). One on-going HMCRP project, HM-07 - Accident Performance Data of Bulk Packages Used for Hazardous Materials Transportation, will help PHMSA respond to these recommendations. The objectives of this research are to: (1) recommend methodologies for collecting and analyzing performance data for U.S. DOT-specified hazardous materials bulk packages (e.g., portable tanks and cargo tank motor vehicles); and (2) identify and evaluate institutional barriers to data collection and recommendations for overcoming these barriers. The HMCRP project HM-07 is expected to be completed by late spring 2012. PHMSA will update NTSB on the progress of this research as it relates to the recommendations.
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