Despite disasters, oil-by-rail transport is getting safer
As pipelines quickly reached capacity, oil shippers turned to the railroads, which provided multiple incentives, including: flexibility in shipping options and contract timelines, shorter transit times to the refineries (five to seven days by rail compared with 40 days by pipeline), and the ability to choose which refineries to use. While pipelines allow for higher volumes to be transported, the higher speed afforded by rail results in reduced transit time for long distances.
As a result, Bakken oil production increased from 81,000 barrels per day in 2003 to more than one million barrels by mid-2014, with more than three-quarters of those barrels moving daily out of North Dakota by rail. While carloads of crude oil increased dramatically, on the whole it still comprises a relatively small portion of total railroad shipments – only about 1.6 percent of all carloads for U.S. Class I railroads.
Because of increased domestic production and increased imports from Canada, 66 percent of U.S. oil demand is now sourced from North America, a shift that’s lowered imports and will create billions of dollars in economic activity over the next several decades.
Assessing the risk
While there exists no universally accepted definition of risk, it is widely accepted that the risk associated with transportation of hazardous materials must factor in both the probability of a release of the hazardous material as well as the magnitude of the consequences of that release.
Statistically, the probability of an oil train derailment is very low, and lower than other forms of transportation. But the potential undesirable consequences are relatively high, including damage to human life, property and the environment.
A worst-case scenario occurred in the Lac-Mégantic accident of 2013 in Canada, which resulted in forty-seven fatalities, another 2,000 people evacuated from their homes, almost 1.6 million gallons of crude oil released and millions of dollars in property damage.
Since 2013, three other notable oil train derailments have occurred in Canada, including recent derailments in Ontario, and seven in the United States, including the recent derailments in West Virginia in February and Illinois in March. Using data available from the FRA Office of Safety Analysis, here is a summary of statistics for US crude oil train derailments from 2013 to 2014:
- eight derailments were reported involving a crude oil release
- two of these derailments resulted in a release exceeding 450,000 gallons
- two of these derailments resulted in a release between 15,000 and 30,000 gallons
- the remaining four derailments resulted in a release of 5,000 gallons or less
- injuries were reported in only two derailments, resulting in four total injuries
- no fatalities were reported in any derailment
- people were evacuated in three of these derailments, with the number of people affected ranging from 16 to about 1,000 people
- track and equipment damage exceeded $1 million for all derailments, with only one derailment resulting in more than $5 million in damages (damage to private property or depreciation of property values not included).
In terms of hazardous materials risk, the consequence to human life was very low in these U.S. incidents, with zero fatalities and only four reported injuries.
Bigger spills
Environmental and economic impacts, however, were substantial. Recent reports have noted that the amount of oil spilled in 2013 alone from train derailments, at more than 1.1 million gallons, was greater than the total amount of oil spilled from 1975 to 2012. As demand for crude oil shipments has increased, railroads have shifted to using “unit trains” in which nearly every car carries oil instead of the variety of railcar types found on a manifest train. For unit oil trains, the only cars that are not tank cars are the “buffer cars,” typically located in the front and rear of the train to provide an added level of safety for the train crew in the event of an accident.
The use of unit oil trains has resulted in larger amounts of oil being spilled in a single derailment. For example, the majority of oil released in 2013 resulted from only two derailments, occurring in Aliceville, Alabama, in November of 2013 and Casselton, North Dakota, in December of 2013. The recent accident in West Virginia on 16 February of this year likely resulted in a release of similar magnitude to the 2013 spills. The accident in Galena, Illinois on 5 March of this year resulted in a spill of over 200,000 gallons of crude oil released from seven tank cars.
The other side of the coin for risk assessment is the probability of release, which is extremely low when compared with other transportation modes. In 2013, which was the worst year to-date for oil train derailments, about 28,000 barrels of oil were released from railroad tank cars out of the approximately 300 million barrels of oil delivered by rail.
In other words, less than one hundredth of 1 percent of the volume of oil transported by rail in 2013 in the United States was released into the environment. According to an analysis of U.S. oil spillage, the amount of oil spilled by railroads per billion ton-mile transported declined by approximately 85 percent throughout the 1990s and 2000s. By comparison, pipelines experienced closer to a 40 percent decline in oil spilled per billion ton-miles over the same period. While this report does not include the recent increase in unit oil trains, it does provide a valuable comparison across transportation modes.
Due to changes in safety culture and numerous technological advances, railroads have continued to improve safety over the last decade, with accident rates reaching all-time lows in 2014 at only 2.24 train accidents per million train miles. The industry has been clear about its goal to continue to use new technologies and improved operating practices to drive accident rates even lower, asserting that “No accident, big or small, is acceptable.”
In our next piece, we’ll look at some technologies that can improve safety.
Bryan W. Schlake is Instructor in Rail Transportation Engineering at Pennsylvania State University. This story is published courtesy of The Conversation (under Creative Commons-Attribution/No derivatives.
