How the US freight rail industry got dirtier than coal power plants

 BNSF Railway, one of the crown jewels of Warren Buffett’s sprawling Berkshire Hathaway conglomerate, calls itself an environmental leader in the U.S. rail industry with the cleanest locomotive fleet in North America.

“When you see our orange locomotives’ and freight cars’ steel wheels moving on steel rails, think green,” BNSF says in its latest sustainability overview.

But the company is the largest player in an industry that has a pollution problem: U.S. freight railroads are a major source of pollution, chuffing out more nitrogen oxide, the primary component of smog, than all the nation’s coal-fired power plants combined, according to a Reuters calculation using government data.

U.S. railroads together produced about 485,000 tons of nitrogen oxide in 2024, compared to 452,000 tons emitted by U.S. coal-fired power plants, according to a Reuters calculation of reported annual fuel consumption multiplied by the EPA’s 2023 weighted-average emission rates.

BNSF, the nation's largest freight railroad, accounts for about a third of that total, producing 161,500 tons of smog-causing nitrogen oxide in 2024, according to the data. “We don't dispute your number. BNSF is the biggest Class I railroad by volume,” BNSF said in an email. 

BNSF's position as largest in the rail industry, as well as its profitability, will be challenged if regulators approve the planned $85 billion merger of Union Pacific and Norfolk Southern, which would create the first U.S. coast-to-coast freight rail operator, Morningstar railroad analyst Greggory Warren said.

Reuters shared its calculations with four industry experts and all agreed it was a fair methodology. About 80% of the industry's NOx tons are produced by Class I railroads, the industry term for the six major railroads with more than $1 billion in annual revenue.

Details on the rail industry’s recent NOx emissions performance, BNSF’s share of those emissions, and the factors driving the ongoing high levels of pollution have not previously been reported.

Railroad locomotive pollution causes an estimated $48 billion in healthcare costs and 3,100 premature deaths annually in the United States, according to the EPA’s Co-Benefits Risk Assessment tool.

“Americans don’t realize how much harmful pollution comes from old diesel locomotives,” said Bill Magavern, policy director for the Coalition for Clean Air, a California group that advocates for public health. “EPA should require the railroad companies to modernize their fleets,” he said.

The EPA declined to comment specifically on rail pollution for this story, but said: "The Trump EPA is committed to enhancing our ability to deliver clean air, water, and land for all Americans.”

AGING FREIGHT LOCOMOTIVES

The railroad industry’s poor emissions performance is due mainly to the fact that it has largely stopped replacing its aging fleet of locomotives. The average age of U.S. locomotives is about 28 years, compared with 20 years in 2009, according to EPA and industry reports.

That's a problem because federal emissions standards for locomotives depend on how old they are with the oldest grandfathered into the lightest limits.

With no requirement to retire old locomotives, the U.S. freight rail industry has dragged its feet on buying new ones, a dynamic amplified by industry fears that new regulations under future administrations could render their investments obsolete, according to Environmental Protection Agency data, and interviews with analysts and railroad executives.

Senator Edward Markey, a Massachusetts Democrat, says railroads have lost their taste for innovation. "Our air pollution standards for railroads have an engine-sized loophole in them, which companies are using to... keep old, dirty trains on the tracks," Markey said in a statement to Reuters.

The rail industry says that it is the cleanest option available to move freight over land, and cites data from the U.S. Department of Transportation. A locomotive can move a ton of freight about 500 miles on a gallon of fuel, which is three to four times more efficient than trucks.

The Association of American Railroads said it was also unfair to compare rail to power plants, saying locomotives have little choice but to burn diesel. "These power plants have multiple other viable options for generation – coal, natural gas, hydropower, wind, nuclear, etc. That is not the case for rail," the trade group told Reuters.

BNSF, meanwhile, told Reuters that it is working to reduce its emissions through efficiency and technology improvements, and stands by its claim to have the cleanest fleet in the industry based on the outright number of modern locomotives in its possession.

BNSF said 360 of its 6,780 total are modern locomotives subject to the strictest federal emissions standards, called Tier 4, the largest outright number in the industry.

That's just 5% of the company's total fleet that is active or in storage, according to Surface Transportation Board data. By contrast, rival Canadian National has nearly 300 Tier 4 locomotives, making up about 27% of its total fleet, according to analysts and CN press releases about new locomotive orders.