Home/American Shipper/Intermodal grew 3% in May American ShipperIntermodal Intermodal grew 3% in May FreightWaves Staff · Friday, June 07, 2013 Facebook Twitter/X LinkedIn Intermodal traffic rose 3 percent, year over year, to 1.21 million containers and trailers, according to the Association of American Railroads. May’s weekly average for intermodal traffic stood at 242,823 containers and trailers.