News & Reviews News Wire Study: Derailment risk rises with the number of cars in a freight train

Study: Derailment risk rises with the number of cars in a freight train

By Bill Stephens | May 29, 2024

| Last updated on May 31, 2024

Researchers analyzed Federal Railroad Administration 2013-2022 wreck data

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A long Union Pacific merchandise train’s head end is well beyond Tunnel 10 while its tail end is still climbing Tehachapi Loop in California in September 2019. Bill Stephens

The risk of derailment increases with freight train length, according to an academic study published today, which found that a 200-car train is 24% more likely to derail than a 50-car train.

The study — by researchers from Brigham Young University, Georgetown University, and Virginia Tech — analyzed Federal Railroad Administration rail equipment accident data from 2013 through 2022.

The researchers then estimated derailment risk while taking into account the reduced overall accident risk that comes from moving freight on fewer but longer trains. They concluded that, compared to a 50-car train, a 100-car train has an 11% higher risk of derailment and that the odds of a wreck rise as the number of cars in a train increases.

“Understanding derailment risk is an important component for evaluating the overall safety of the rail system and for the future development and regulation of freight rail transportation. Given the limitations of the current data on freight train length, this study provides an important step toward such an understanding,” the study’s authors said.

The Rail Safety Act of 2023, which was proposed in the wake of the disastrous Feb. 3, 2023, hazardous materials wreck in East Palestine, Ohio, proposes capping train length at 7,500 feet. That translates into roughly 121 cars based on a 62-foot average car length.

The National Academy of Sciences, meanwhile, is nearing completion of a study that evaluates the safety effects of operating trains longer than 7,500 feet. That study was ordered as part of the Bipartisan Infrastructure Law that was passed in 2021.

Rail labor union leaders have been highly critical of the Class I railroad practice of operating ever-longer trains, claiming that longer trains are inherently unsafe despite the expanded use of distributed power, smart cruise control systems, and advanced train-building software.

The Association of American Railroads, meanwhile, contends that long trains have been operated safely for decades, and the industry’s safety record has improved even as train length has risen. Last year the median Class I freight train length was 5,300 feet. Some 10% of trains were longer than 10,000 feet, while fewer than 1% topped 14,000 feet, according to AAR data.

The study’s authors, Peter Madsen of BYU, Robin Dillon of Georgetown, Konstantinos Triantis of Virginia Tech, and Joseph Bradley of BYU, said elected officials and regulators should take into account more factors than derailment risk. The use of longer trains is a complex and multifaceted issue, they noted.

“Longer freight trains have many significant benefits for the rail system relative to shorter freight trains, including greater fuel efficiency, lower emissions per ton transported, and lower operational costs than both shorter trains and many other forms of transportation,” they wrote. “The operation of longer freight trains also comes with costs such as increased wait times at railroad grade crossings for road vehicles in communities where freight trains frequently operate. Additionally, as recent cases like the East Palestine derailment demonstrate, derailments can have significant negative environmental and health impacts on communities, although rail remains a safer mode of transportation for hazardous chemicals than other options.”

Representatives for the Federal Railroad Administration and Association of American Railroads said they were reviewing the study and its conclusions.

Previous studies and reports have not found a relationship between train length and likelihood of derailment, although those studies said more research was required due to a lack of data.

“The major challenge to examining the relationship between freight train length and the risk of derailment is the lack of available exposure data. Although the length of trains involved in accidents is included in accident reports that railroads file with the Federal Railroad Administration, data on the lengths of trains that are not involved in accidents are largely unavailable. This lack of ‘exposure’ data has precluded estimating the derailment risk by freight train length using traditional methods,” the BYU, Georgetown, and Virginia Tech researchers wrote.

To get around the paucity of data on trains that did not derail, the researchers derived estimates using a technique that highway accident researchers rely upon. It is the first time this technique has been used to study rail accidents, they wrote.

The study, “The relationship between freight train length and the risk of derailment,” was published in the journal Risk Analysis.

11 thoughts on “Study: Derailment risk rises with the number of cars in a freight train

  1. Laughing to see the comments from model railroaders. Millions of studies on this have occurred over the many years of the model railroading hobby. First thing to pop in my mind, so glad to see others see it as obvious as well.

    Now a nice physics theory on why derailing increases with longer trains, that I could get into reading!! Sounds like a thesis for some PhD candidate!!

    1. Does anyone run 50 car trains anymore (or even 100 car trains – few) other than shortlines and a few special moves? Most trains I see anymore are between 10,000 and 16,000 feet long. If proper operational mechanics were followed and all the empties were at the rear of the trains, behind the DPU’s, instead of scattered through out, then string-line derailments would be almost nil and buff forces would be greatly reduced. Wheel and rails will break but the better the science gets even that can be minimized. Buff forces is a whole “nother” problem and only rules that can be forced with huge penalties will ever bring those under control I fear, just as the reciprocal switching rules were proposed and put in place because the railroads refused to acknowledge there was a problem…

  2. they needed a study for that. I could have told them longer train are more prone to derailment for free.

  3. Train length is just one part of the equation.

    Train make-up is a third of the equation. With the push to pre-block trains, the distribution of various car sizes and loads vs. empties plays a significant role in buff and draft forces.

    The other third is the operating territory. Running 200 cars across Nebraska is strikingly different that running through the mountains of Virginia.

  4. But unless you have hard data to back it up, railroad executives will say there is no data to prove that theory. It’s more than just length. The constant forces on the track structure is a problem.

  5. I’m relatively certain you can walk into any model railroad club and learn the same lesson without spending whatever was expended on this study.

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