The National Transportation Safety Board, at a public meeting held yesterday on its investigation of a severe tractor-tanker rig rollover accident, revealed 20 recommendations it will likely make in its final report to improve safety.
Among the likely recommendations will be a directive to the Federal Motor Carrier Safety Administration to mandate the retrofitting of stability-control systems on tanker rigs (with GVWRs over 10,000 lbs.) and having the National Highway Traffic Safety Administration “develop stability control system performance standards for all commercial motor vehicles and buses (with GVWRS over 10,000 lbs.) regardless of whether the vehicles are equipped with a hydraulic or a pneumatic brake system”… and once such [system] performance standards are developed “require the installation of stability control systems on all newly manufactured commercial vehicles (with GVWRs above 10,000 lbs.).”
The safety board is making final revisions to the report and recommendations, NTSB said.
The accident investigated that led to the NTSB recommendations occurred nine months ago. This is an abridged version of what NTSB said happened:
“On Oct. 22, 2009, about 10:38 a.m. [EDT], a 2006 Navistar International truck-tractor in combination with a 1994 Mississippi Tank Co. MC331 specification cargo tank semitrailer, operated by AmeriGas Propane, L.P., and laden with 9,001 gals. of liquefied petroleum gas, rolled over on a ramp after exiting I-69 southbound to proceed south on Interstate 465, about 10 miles northeast of downtown Indianapolis…..
”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.”
Both the truck driver and the Volvo car driver sustained serious injuries in the accident and post-accident fire, noted NTSB, and three occupants of passenger vehicles traveling on I-465 received minor injuries from the post-accident fire.
NTSB said the probable cause of the accident was “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 roll over 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.”