Home/American Shipper/AAR: U.S. rail traffic full speed ahead in March American ShipperShippingTrade and Compliance AAR: U.S. rail traffic full speed ahead in March FreightWaves Staff · Friday, April 06, 2018 Facebook Twitter/X LinkedInTotal U.S. freight rail volumes grew another 5 percent for the month following a 3.3 percent gain in February, according to the latest data from the Association of American Railroads (AAR). N/A