. gross and revenue-ton-miles increased 5% ( 5 % ) in 2011 compared to 2010 , driven by a 3% ( 3 % ) increase in carloads and mix changes to heavier commodity groups , notably a 5% ( 5 % ) increase in energy shipments . gross and revenue-ton-miles increased 10% ( 10 % ) and 9% ( 9 % ) , respectively , in 2010 compared to 2009 due to a 13% ( 13 % ) increase in carloads