Freight carload traffic on U.S. railroads dropped 0.4% in the week ending Aug. 3 compared with the same period a year ago, but intermodal rose 4.8%, according to the Association of American Railroads. For the month of July, intermodal volume was 2.5% above last July's level, which helped offset a 0.5% decline in carload activity. July shipments of petroleum and petroleum products rose 24.9% above the year-ago level. "Coal and grain traffic is down for reasons that have little or nothing to do with the state of the economy. The remaining rail traffic segments are mixed, reflecting an economy that's moving in the right direction but not firing on all cylinders," said John Gray, AAR senior vice president.