Ever drink purified water? Like having a warm home in the winter? What about taking prescription medicine, or spreading fertilizer across a vegetable garden?

From clean water to comfortable homes, many of the things people rely on every day are made with, or are made better with, hazardous materials like chlorine dioxide, heating oil, and ammonium nitrate.

But there’s a reason they’re called hazardous materials: when they spill during transport, they can be hazardous to public health. Because these materials are vital, it’s also vital that commercial cargo tank trucks move them safely.

Digging into Tanker Rollover Data to Improve Safety

As of 2012, accidents involving cargo tank trucks were the leading cause of injury and death from hazardous material transportation incidents. The Pipeline and Hazardous Materials Safety Administration (PHMSA) turned to U.S. DOT’s Volpe Center to investigate real-life rollovers and current training programs, and to develop recommendations to improve cargo tank safety.

Volpe human factors experts analyzed 93 case studies of cargo tank rollovers from 2011 to 2014, along with a sample of national crash statistics from this same time period. They found that the average number of cargo tank rollovers has decreased compared to data from a decade ago.

“The good news is we’ve seen a lot of recent improvements specific to cargo tank safety,” said Clark Calabrese, the lead data analyst on the Volpe team. “And we’ve also seen technologies like systems that keep you from exiting your lane, speed controls, cab monitoring, all which could improve safety in tanker trucks.”

There has not, however, been a clear overall downward trend in cargo tank rollovers, according to this final report from the Volpe team. These findings suggest that new technologies are not consistently preventing rollovers specifically for tanker trucks, or that these technologies are not used widely enough, particularly by smaller carriers, according to the report.

Tanker-Specific Training

When it comes to reducing cargo tank rollovers, effective training is as important as new technology.

Transporting hazardous materials requires specialized knowledge. Liquid hazardous material sloshing around a tank will act differently than heavy wooden pallets.

The Volpe team recommended five efforts to ensure robust training specific to driving tanker trucks:

1. PHMSA and the Federal Motor Carrier Safety Administration (FMCSA) should collaborate to develop a Tank Vehicle Endorsement Curriculum with guidelines including use of the PHMSA/FMCSA Rollover Prevention Training Video.
    
2. Section 8 Tank Vehicle, a chapter in the commercial driver’s license manual, should be redesigned to be less ambiguous. Information relevant to tank vehicles should be in that section, information that is relevant only for box trailers should be deleted, and recommended behaviors should be specific and, where appropriate, quantified.
    
3. The tanker industry should explore the benefits of signage specific to tank-vehicle rollover, with recommended speed limits for curves and ramps to determine safe tanker speeds under varying tank load conditions and roadway geometries.
    
4. PHMSA and FMCSA should work with the tanker industry to develop incentives for tanker carriers to adopt advanced safety technology.
    
5. PHMSA should revise federal regulations to clarify that training requirements are satisfied by meeting requirements for a commercial driver’s license and appropriate endorsements.

The Human Complexity Factor

Driver performance errors made up about half of the rollovers studied. Overall, driver performance was the largest contributing factor to these rollovers. Updated training can help—but Calabrese stresses that the hazmat transportation system is complex.

The performance of a single driver can be influenced by the training he or she received, the company for which he or she was hired, the agencies that regulate his or her responsibilities, the behavior of other vehicles on the road, and societal attitudes toward truck driving.

“Attributing an accident to human error is an incomplete understanding of any situation,” Calabrese said. “Usually you need to take into account a larger system. If a driver falls asleep because of a strong motivation to work too many hours, this is part of a greater situation that affects whether an accident occurs. It’s reductive to simply say that a driver made a mistake.”

Read the report: Cargo Tank Incident Study: Rollover Data and Risk Framework