Indianapolis, Indiana
October 22, 2009
NTSB Number: HAR-11-01
NTIS Number: PB2011-916201
Adopted: July 26, 2011
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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 National Transportation Safety Board determines 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.
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. At the time of the accident, the sky was overcast, winds were calm, pavement was dry, and the temperature was about 58° F.
The following safety issues were identified in this investigation:
As a result of its investigation of this accident, the National Transportation Safety Board makes the following recommendations:
To the U.S. Department of Transportation
Require all intrastate and interstate hazardous materials carriers to submit annually the number and types of U.S. Department of Transportation specification cargo tanks that are owned or leased in addition to data displayed on the specification plates of such tanks and, if necessary, modify the appropriate database to accept additional data fields. (H-11-1)
To the Federal Motor Carrier Safety Administration
Work with the Pipeline and Hazardous Materials Safety Administration, as appropriate, to develop and disseminate guidance that will assist hazardous materials carriers in implementing comprehensive cargo tank motor vehicle rollover prevention programs, including the active participation of drivers, dispatchers, and management through training, loading practices, delivery schedules, and acquisition of equipment. (H-11-2)
Require all in-use cargo tank trailers with a gross vehicle weight rating greater than 10,000 pounds to be retrofitted with a rollover stability control system. (H-11-3)
To the Pipeline and Hazardous Materials Safety Administration
Work with the Federal Motor Carrier Safety Administration, as appropriate, to develop and disseminate guidance to assist hazardous materials carriers in implementing comprehensive cargo tank motor vehicle rollover prevention programs, including the active participation of drivers, dispatchers, and management through training, loading practices, delivery schedules, and acquisition of equipment. (H-11-4)
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. (H-11-5)
Once the performance standards in Safety Recommendation H-11-5 have been developed, require that all newly manufactured cargo tanks comply with the performance standards. (H-11-6)
To the National Highway Traffic Safety Administration
Develop stability control system performance standards for all commercial motor vehicles and buses with a gross vehicle weight rating greater than 10,000 pounds, regardless of whether the vehicles are equipped with a hydraulic or a pneumatic brake system. (H-11-7) This safety recommendation supersedes H-10-5.
Once the performance standards from Safety Recommendation H-11-7 have been developed, require the installation of stability control systems on all newly manufactured commercial vehicles with a gross vehicle weight rating greater than 10,000 pounds. (H-11-8). This safety recommendation supersedes H-10-6.
Establish comprehensive minimum rollover performance standards, based on the least stable condition operated, for all newly manufactured cargo tank motor vehicles with a gross vehicle weight rating greater than 10,000 pounds. (H-11-9)
Once the performance standards in Safety Recommendation H-11-9 have been developed, require that all newly manufactured cargo tank motor vehicles with a gross vehicle weight rating greater than 10,000 pounds comply with the performance standards. (H-11-10)
Evaluate the effect of emergency maneuvers on the sloshing and surging of bulk liquids that have various densities over a range of partially filled levels in a U.S. Department of Transportation specification cargo tank. (H-11-11)
If the results of Safety Recommendation H-11-11 warrant action, establish and implement performance standards for mitigating the sloshing and surging of bulk liquids in all newly manufactured cargo tank motor vehicles with a gross vehicle weight rating greater than 10,000 pounds. (H-11-12)
To the Federal Highway Administration
Work with the American Association of State Highway and Transportation Officials to evaluate vehicle design characteristics specific to the rollover thresholds of heavy trucks, including those having cargo tanks. Use the information obtained to develop best practices in highway design that will mitigate the increased rollover risk caused by reduced effective superelevation through changes in cross slope that high center of gravity commercial vehicles experience when they migrate onto the shoulder while negotiating curve sections of high-speed highways. (H-11-13)
If the results of the evaluation in Safety Recommendation H-11-13 warrant such action, work with the American Association of State Highway and Transportation Officials to develop and implement best practices to assist state transportation agencies in identifying existing locations where cross-slope breaks pose a rollover hazard, placing an emphasis on those roadways having high volumes of heavy truck traffic, and develop appropriate strategies for mitigating the hazard. (H-11-14)
Until the best practices in Safety Recommendations H-11-13 and -14 have been developed and disseminated, provide information to state transportation agencies about the safety risks associated with cross-slope breaks and their potential for increasing the rollover propensity of commercial vehicles that have a high center of gravity. (H-11-15)
Work with the American Association of State Highway and Transportation Officials to develop guidance for a bridge pier protection program that will allow state transportation agencies to conduct risk-based assessments of bridges located within highway interchanges. At a minimum, the program should consider each structure's redundancy, continuity, and the distance of bridge pier columns from the edge of traveled ways. Additionally, consider traffic volumes, traffic type, and the percentage of commercial vehicles transporting bulk liquid hazardous materials in identifying and prioritizing initiatives for preventing vulnerable bridges at high-risk interchanges from collapsing if struck or otherwise damaged by a heavy vehicle. (H-11-16)
Once the guidance for a bridge pier protection program as described in Safety Recommendation H-11-16 has been developed, require that it be applied to bridges that are vulnerable to collapse if struck by a heavy vehicle. (H-11-17)
To American Association of State Highway and Transportation Officials
Work with the Federal Highway Administration to evaluate vehicle design characteristics specific to the rollover thresholds of heavy trucks, including those having cargo tanks. Use the information obtained to develop best practices in highway design that will mitigate the increased rollover risk caused by reduced effective superelevation through changes in cross slope that high center of gravity commercial vehicles experience when they migrate onto the shoulder while negotiating curve sections of high-speed highways. Also, incorporate the findings in the American Association of State Highway and Transportation Officials publication A Policy on Geometric Design of Highways and Streets. (H-11-18)
If the results of the evaluation in Safety Recommendation H-11-18 warrant such action, work with the Federal Highway Administration to develop and implement best practices to assist state transportation agencies in identifying existing locations where cross-slope breaks pose a rollover hazard, placing an emphasis on those roadways having high volumes of heavy truck traffic, and develop appropriate strategies for mitigating the hazard. (H-11-19)
Work with the Federal Highway Administration to develop guidance for a bridge pier protection program that will allow state transportation agencies to conduct risk-based assessments of bridges located within highway interchanges. At a minimum, the program should consider each structure's redundancy, continuity, and distance of bridge pier columns from the edge of traveled ways. Additionally, consider traffic volumes, traffic type, and the percentage of commercial vehicles transporting bulk liquid hazardous materials in identifying and prioritizing initiatives for preventing vulnerable bridges at high-risk interchanges from collapsing if struck or otherwise damaged by a heavy vehicle. (H-11-20)
The National Transportation Safety Board classifies the following previously issued recommendations:
Safety Recommendation H-95-39 to the American Association of State Highway and Transportation Officials is classified "Closed—Reconsidered" in the "Cross-Slope Break" section of this report's Analysis.
Safety Recommendations H-10-5 and -6 to the National Highway Traffic Safety Administration are classified "Closed—Superseded" in the "Stability Control Systems" section of this report's Analysis.
