Norfolk Southern Corp. is blaming merchandise and coal traffic for a drop in its railway operating revenue in its recent quarterly earnings report, though recent increases in exports of the commodity have cushioned the fall.

The company said on Jan. 25 that the railway operating revenue dropped 1% in the fourth quarter of 2016 compared to the same period in 2015.

Coal revenues fell by 7% to $403 million compared to the fourth quarter of 2015, while volume fell 4% between those periods, though Norfolk said an increase in exported coal softened that decline.

Year-over-year coal revenues for the railway fell more steeply, dropping 18% to $1.5 billion. "Reduced utility volumes combined with a weak global export market lowered total volume by 16%," said the Norfolk release.

CSX Transportation Inc. also reported that coal took a bite out of its earnings in the fourth quarter of last year.