It may seem odd that CSX – a freight train company based in Florida – has been placing advertisements across television airways in recent weeks. Companies whose main clients are other companies (like freight movers) don’t often engage in television advertising. They avoid the cost because they don’t rely on individual consumers as part of their business model (Memorable exceptions include ads representing Siemens, and Tyco).
Regardless of their motives, CSX’s advertisements make a seemingly improbable claim: that their freight trains move 1 ton of cargo 436 miles on 1 gallon of gas. Is this possibly true?
While these numbers may seem far-fetched, they may be based in fact.
CTLS Director Dr. Nicholas Lownes – a Civil and Environmental Engineer at the University of Connecticut – said in a recent interview that he “always understood that this type of claim is in line with reality.”
He continued to say “[CSX’s] idea is that steel wheels, on steel rail are the most efficient way to transport cargo. This method has the least amount of friction possible. Once a train is rolling, it takes the least amount of effort to keep it moving.”
When you compare the friction of steel-on-steel to the friction of rubber tires on pavement, there is a large difference in the amount of energy dissipated due to friction, Dr. Lownes said.
Because a rubber tire riding on pavement causes a large amount of friction “the engine has to make up for that lost energy. The efficiency comes down to how the physics behind the transportation modes work,” he said.
So, the physics behind CSX’s claims of 436 ton-miles-per-gallon seem to be valid, but Dr. Lownes notes that “this average value masks a lot of variability across the country.”
Though the Association of American Railroads (AAR) – a group which advocates for safety and environmental concerns – announced in 2010 that the average ton of railroad freight in the U.S. moves 480 miles on a single gallon of gas, Dr. Lownes suggests that these kinds of numbers may not reflect the true efficiency of trains across the country.
“Not all trains achieve that kind of efficiency,” he said. “When you have a giant train with 50 cars behind it, and you get it rolling over Nebraska and Kansas where there is no elevation change, and nothing to stop for, it doesn’t take that much additional energy to keep those thousands of tons moving.”
On the other hand, trains traveling across the Appalachian Mountain Range will probably have worse efficiency.
It is important to remember that these numbers are averages, and the efficiency of trains moving in perfect conditions can skew this number to be misleadingly high. This is an issue common to the use of averages, as is explained here.
The AAR acknowledges the ‘averages problem’ in its report: “480 [ton-miles per gallon] was the average last year for all rail traffic across all Class I railroads – that means for some trains and some rail traffic, the corresponding figure will be much higher, while for others it will be lower.”
The questionable validity of the specific statistic of 436 miles on 1 gallon of fuel does not detract from CSX’s overarching point: that trains are more efficient ways of transporting freight than traditional truck-and-trailers. But, whether CSX and other freight companies truly transport 1 ton of cargo over 400 miles on a single gallon of fuel is a relatively hard fact to verify.