AAR said 10 of the 20 carload commodity groups posted increases compared with the same week in 2011, led petroleum products, up 49%, motor vehicles and equipment, up 35.7%, and lumber and wood products, up 20.3%. Coal led the declining commodities, off 16.2%, while nonmetallic minerals fell 15.4% and grain declined 11.4%.

Canadian freight carload volume kept its positive momentum for the year, up 3.4% in the week ending May 12, while Canadian intermodal also advanced, up 7.2%. Mexican freight carload volume rose as well, up 6.2%, and Mexican intermodal volume notched a 16.2% gain.

Combined North American freight carload volume for the first 19 weeks of 2012 on 13 reporting U.S., Canadian, and Mexican railroads was down 1.8% compared with the same point last year, while combined intermodal volume for the period was up 4.2%.