Hazardous Materials Cargo Tank Rollovers: A Significant Challenge to Reducing Hazmat-Related Fatalities

Cargo tank motor vehicles, also known as tankers or tank trucks, are a familiar sight on U.S. highways.  While they may be best recognized for transporting gasoline to filing stations, tankers actually transport a wide variety of both hazardous (gases, industrial chemicals) and non-hazardous (cement, milk, water) materials.  These vehicles and their drivers provide vital services by transporting our goods, heating our homes and driving our economy.

Though tankers are a useful tool for companies that transport hazardous liquids and gases, they have inherent dangers given their high center of gravity, which makes tankers more challenging to drive.  The fact is that there are thousands of safe deliveries made in tank trucks each day and the tank truck industry has a better accident ratio than other segments.  Obviously, when a crash does occur, the results can be more dramatic if a hazardous material is released.  The average annual number of cargo tank rollovers nationwide is approximately 1,250 per year, with an estimated 15-20 percent of those incidents taking place on U.S. freeways, according to a 2007 FMCSA study. Reducing the number of cargo tank rollovers, particularly those transporting hazmat, should be a top priority for U.S. transportation safety officials.

Each year there are approximately 12-15 fatalities related to hazardous materials incidents in transportation.  Rollovers account for nearly 75 percent of these fatalities.  This is not surprising, considering that the most commonly transported hazardous material commodity is gasoline, which is predominantly transported in cargo tank trucks.

Driver error related to either a decision or performance error figures in about 75 percent of the cargo tank rollovers.  Driver errors can generally be characterized into four types:

  • Driver decision error – the driver decides to perform the wrong evasive maneuver
  • Driver non-performance error – the driver fails to perform the required maneuver correctly
  • Driver performance error – the driver is incapacitated and is unable to perform the task
  • Driver recognition error – the driver fails to recognize the need to make a maneuver that would prevent the accident

Driver decision error is the most common of these scenarios, contributing to about 40 percent of the driver errors.  This correlation indicates that, with better training, the driver might do something differently and avoid the rollover accident.

Preventing hazmat cargo tank rollovers has been on the radar of U.S. government officials for a number of years.  In 2008, Pipeline and Hazardous Materials Safety Administration (PHMSA) senior leadership partnered with the Federal Motor Carrier Safety Administration (FMCSA) and the National Tank Truck Carriers, Inc. (NTTC) to craft a focused effort geared towards reducing cargo tank truck rollover incidents.  The tank truck safety task force, with the involvement of key stakeholders, developed a multipoint action plan which included numerous action items and deadlines for completion.  The plan was developed based on lessons garnered from a study entitled “Cargo Tank Roll Stability Study,” which was contracted by the FMCSA with Battelle.  The study evaluated four complementary approaches to reducing the number of cargo tank truck rollovers: redesigning the vehicle, redesigning the highways, deploying electronic stability aids, and improving the training of drivers.

Cargo Tank Rollovers Video

The task force took a multifaceted approach to reducing rollovers and enhancing tank truck designs, driver training, use of electronic stability control systems and other measures that can be effective in addressing the challenge.  Efforts geared toward reducing driver error included a training video developed jointly by PHMSA, FMCSA and NTTC.  The Cargo Tank Rollover Prevention Video is available from NTTC at no cost with Spanish subtitles at the NTTC Web site. A driver education program was also initiated that included safety posters, rollover prevention tips and information that was placed in driver correspondence (such as pay stubs mailed to the homes of drivers).

The Transportation Research Board (TRB) also completed a research study (HM-13) under the Hazardous Materials Cooperative Research Program. The research study considered the role of human factors in cargo tank rollovers, and contains a variety of useful information and tips for training.

After a rotation of senior leadership within PHMSA, the agency has refocused its effort on this high-risk problem. This is encouraging, since these incidents typically result in significant impact to not only to human life but to the nation’s infrastructure. Take, for instance, a 2007 incident in which a gasoline tanker truck overturned on the Bay Bridge ramp leading to San Francisco. The resulting fire caused a portion of the ramp to collapse onto an interstate highway below, cutting off the return route to San Francisco for many East Bay commuters.  It was estimated that the Bay Bridge ramp collapse resulted in $4-6 million a day in extra commuting costs and lost business.

Extensive property damage, economic and personal disruption from immobilizing traffic, and the evacuation of homes and businesses is not uncommon in hazmat cargo tanker crashes.  In addition to fatalities, injuries and property damage, there are significant costs and burdens on the transportation system which contribute to congestion.  The real costs associated with these incidents are much greater than those reported.  According to a national report issued in 2001, hazmat crashes accounted for slightly more than $1 billion a year in cost impact to society.

Taking the steps necessary to reduce the number of hazmat cargo tank rollovers should be a top priority for U.S. government officials. The cost/benefit-savings would be significant and, more importantly, a considerable number of lives would be saved each year.  John Conley from the NTTC stated:

“While cargo tank rollovers are rare given the number of tank truck loads dispatched every day, including over 100,000 loads of gasoline, our goal must be to eliminate all rollovers.  Rollovers are a real issue and industry through National Tank Truck Carriers continues to work with the U. S. Department of Transportation and other agencies to solve the problem.  NTTC supports the mandate of electronic stability control on tractors used in cargo tank operations and has had that policy since 2008. However, we know that at least 75 percent of rollovers are the result of human error and almost all rollovers are preventable. Proper hiring and training of drivers are important, but drivers must continuously be reminded that they are key to eliminating rollovers.”

NTTC is currently working with PHMSA and FMCSA to build on the Rollover Prevention Toolkit to help spread the message.

* * * * *

We spoke with Magdy El-Sabaie, PHMSA Associate Administrator for Hazardous Materials Safety, about efforts to address cargo tank truck rollovers.  He provided a staff response to a series of questions regarding the agency’s efforts.  William Quade, Associate Administrator for Enforcement and Program Delivery at FMCSA, also informed us about efforts that his agency has underway.  The following Q&A is a result of conversations with both parties:

How many tank truck rollovers occur in the US on a daily basis involving vehicles both carrying hazmat and those that carry general freight?  We understand this may be as high as 5 per day. 

In February 2007, Battelle concluded there were 1,265 annual (3.5 per day) CTMV transporting hazmat and non-hazmat events that resulted in rollover.  Battelle also concluded there were 680 annual (1.9 per day) CTMV transporting hazmat events that resulted in rollover.

How many serious hazmat incidents and fatalities are attributed to cargo tank truck rollovers per year over the past 5 years?  Have the number of incidents declined or generally remained flat?

As reported to PHMSA, from 2005-2011 there were a total of 1,278 CTMV rollover incidents.  Out of those incidents, 45 incidents resulted in a fatality for a total of 53 fatalities.  The data shows there was a decline in incidents until 2009 when we instituted the telephonic process.  That change caused an increase over a short time frame and has remained flat since.

What are the most common commodities involved in these incidents (e.g. gasoline, diesel fuel, etc.)?

The most common commodities involved in these incidents are as follows:

  1. Gasoline (UN1203)
  2. Diesel Fuel (NA1993)
  3. Flammable Liquid, N.O.S. (UN1993)
  4. Petroleum Crude Oil (UN1267)
  5. Liquefied Petroleum Gas (UN1075)

In relation to the overall hazmat transportation risks that PHMSA is addressing where does cargo tank rollover prevention rank? What priority is placed on preventing cargo tank rollovers? 

Cargo tank crashes and rollovers involving hazmat releases account for about a third of hazmat incidents that cause death or injury. This is the leading recorded cause of hazmat incidents with casualties and is notable in any context.  Nonetheless, this should be considered in light of a few other points:

  1. Transportation of bulk flammable liquids by highway represents a large portion of all hazmat transportation.
  2. Incidents per gallon of gasoline and per gallon of diesel fuel in the economy have dropped steadily, year-to-year, over at least the past 20 years.
  3. Rollovers are a problem best addressed through a coordinated DOT (FMSCA, NHTSA, FHWA, and PHMSA) action.  Together the Department is working to identify, understand and address the problem.

I understand that PHMSA previously developed a cargo tank truck rollover prevention plan with specific milestones that was developed in partnership between PHMSA, FMCSA, NHTSA and NTTC.  One of the actions that has been completed was a driver awareness video.  The video was really well done and hopefully is having a proactive impact.  Other issues included a rulemaking initiative by NHTSA to mandate safety features on vehicles such as electronic stability control and raking systems.  What progress has been made in this respect and with respect to any other ongoing roll over prevention initiatives?

On May 23, 2011, NHTSA published an NPRM (77 FR 30766) to require electronic stability control on combination vehicles which should reduce the number of rollovers in the future.

PHMSA initiated a Cargo Tank Rollover Special Study reviewing incident and collecting additional data such as: configuration of cargo tank; description of overturn protection devices; degree and direction of rollover, type; and extent of damage to truck and ground conditions.  This study is slated for completion in April 2013 and should provide valuable data to assist in cargo tank truck rollover protection.

What have you learned from the recently released findings from the first phase of a three-part research effort aimed at helping reduce large truck rollovers by the American Transportation Research Institute (ATRI)? This study is aimed at establishing a database that identifies rollover “hot spots” across 31 states.  I understand that rollover incidents typically occur in “incident hot spots”.  What can the agency do to use this information to prevent rollovers?

While the ATRI study has more potential for helping FHWA take actions such as improving signage in hotspots, the data can also help PHMSA and FMCSA consider specific areas for enhanced outreach activities that might raise awareness and reduce rollovers.  Some local agencies have posted warning signs in these hotspot areas.

What current actions are focused on reducing cargo tank truck incidents and fatalities?

On May 23, 2011, NHTSA published an NPRM (77 FR 30766) to require electronic stability control on combination vehicles which should reduce the number of rollovers in the future.  In addition, a six-month special study is underway to collect additional data on cargo tank motor vehicle rollovers.  This information will be in addition to that provided on the DOT 5800 form and enable us to better understand the effectiveness of the current overturn protection devices.

I understand that your field staff continue to investigate rollover incidents to better understand the root causes and to more effectively identify effective preventative measures.  Please summarize your efforts in this regard and what if anything you have learned as a result. 

Since 2005, over 150 cargo tank rollover incidents have been reported each year.  As a result, PHMSA initiated a six-month focused study on October 1, 2012 to collect additional information from multiple sources that were involved in cargo tank rollover incidents.  To date, PHMSA is reviewing information from 18 cargo tank rollover incidents.  In collecting information from these 18 incidents, it is important to note that carriers have been very cooperative in providing the requested additional information.  PHMSA and FMCSA are working cooperatively on this initiative.

What other agencies and stakeholders is PHMSA engaging in their prevention efforts?

We are working with FMCSA, NHTSA and FHWA.  We have worked with NTTC in the production of the overturn video.  We are working to address several NTSB recommendations related to this issue.

Is there an effort to develop a cargo tank rollover prevention toolbox?

Under NTSB recommendation H-11-4, we are looking at a comprehensive plan and are currently conducting a policy analysis. In addition, FMCSA is working to establish a Rollover Prevention Toolbox on the FMCSA website.  At this time, design of the site and content review are under way.  One feature of the toolbox will be the ability to link to ATRI’s Mapping Large Truck Rollovers: Interactive Map.  PHMSA and FMCSA plan on working closely with the industry on identifying and developing content for the site.  It is expected that the Rollover Prevention Toolbox will make its debut by early Spring of 2013.

What else would you like to add personally about the agency’s efforts, progress and future direction with respect to reducing serious incidents and fatalities involving cargo tank truck rollovers?

Rollovers are a serious concern for PHMSA, and we are looking at risks related to both combination and straight trucks.  We will continue to work with our Federal Partners and Stakeholders in addressing safety concerns related to rollovers.

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