AAR said nine of the 20 carload commodity groups it measures posted increases compared with the same week in 2011, led by petroleum products, up 54%, motor vehicles and equipment, up 13.2%, and food and kindred products, up 11.5%. Pacing the declining commodity groups were metallic ores, down 33.3%, coal, down 12.1%, and metal and products, down 10.8%.

Canadian freight carload volume edged up 1.0% for the week ending Sept. 22 compared with the same period a year ago, while Canadian intermodal rose more robustly, up 10.1%. Mexican freight carload volume also gained, up 3.2%, while Mexican intermodal also showed strength, up 11.7%. 

Combined North American freight carload traffic for the first 38 weeks of 2012 on 13 reporting U.S., Canadian, and Mexican railroads was down 1.3% compared with the same time span in 2011. Combined North American intermodal volume for the period, by contrast, was up 4.6%.