Home/American Shipper/Coal traffic slumps for U.S. railroads American ShipperIntermodal Coal traffic slumps for U.S. railroads FreightWaves Staff · Monday, April 09, 2012 Facebook Twitter/X LinkedInU.S. railroads moved 5.8 percent fewer new carloads in March compared to a year ago, but intermodal volume increased 3.5 percent to 928,350 containers and trailers, the Association of American Railroads reported.