NHTSA Eyes Stability Systems to Prevent Tanker Rollovers
This story appears in the Aug. 9 print edition of Transport Topics.
Requiring stability control systems to be installed on all heavy-duty trucks would prevent nearly 3,500 rollovers, save 106 lives and eliminate nearly 4,400 injuries in the United States every year, a top federal highway official said last week.
Nathaniel Beuse, director of crash avoidance standards at the National Highway Traffic Safety Administration, told National Transportation Safety Board investigators his estimate was based on a study conducted by the University of Michigan Transportation Research Institute.
Beuse made his comments during a two-day NTSB board of inquiry hearing into an October 2009 tank-truck rollover accident in Indianapolis that resulted in damage to nine vehicles, serious injury to two drivers and minor injuries to several other people.
NTSB Chairwoman Deborah Hersman said the agency has been concerned about tanker rollovers “for more than 40 years. While cargo-tank vehicles represent approximately 6% of large trucks, they account for 31% of all fatal commercial-truck rollover crashes.”
The board said its Aug. 3-4 hearing in Washington was intended to gain insight into the causes of cargo-tank truck rollovers and explore ways to reduce mishaps through roll stability technologies, highway design, vehicle design, driver training and crashworthiness standards.
Although all new passenger vehicles currently are required to have stability control systems, that mandate does not cover commercial trucks. Beuse said that NHTSA is hoping to complete a study of the benefits of stability systems by the end of this year, and some systems manufacturers have said they believe a federal mandate will be issued soon thereafter.
Largely because of cost concerns — retrofit and new stability technologies can range from $600 to $2,000 per vehicle — only about 15% of new heavy trucks sold have stability control systems, said Alan Korn, director of vehicle dynamics and control systems for Meritor WABCO.
Beuse said that more sophisticated electronic stability control systems that automatically slow down or brake heavy trucks when sensors recognize rollover danger would be even more effective in reducing traffic accidents than the more common systems today. The UMTRI study said the ESC systems could prevent 4,659 crashes, 126 fatalities and 5,909 injuries.
Hersman said cargo tank vehicles are more susceptible to rollovers because of their high center of gravity. A recent Battelle Memorial Institute study concluded that lowering the center of gravity of tankers by 3 inches could reduce rollovers by more than 10%, Hersman said.
Douglas Pape, a senior research engineer for Battelle, said speed is a factor in less than half of all tank-truck rollovers, and only one in 10 occurs on freeway ramps. More than half of all tanker rollovers are the result of roadway departures, Pape said.
In addition, more than 53% of these rollovers caused by excessive speed in a curve could be prevented with roll-stability systems, according to the study.
Neil Voorhees, director of safety services and security for bulk carrier Trimac Transportation Services USA, told the board that of its 1,200 tractors, 356 have stability-control systems and 97 have electronic stability-control systems.
As a result, the carrier has seen a steady decline in rollovers — from 13 in 2007 to only one so far this year, Voorhees said.
At the hearing, James Simmons, chief of the Federal Motor Carrier Safety Administration’s hazardous materials division, stressed the importance of driver training.
Driver error plays a significant role in about 75% of all cargo-tank rollovers, Simmons said.
