ATLANTA — Heightened intermodal competition took a toll on Norfolk Southern’s volume, revenue, and profits in the fourth quarter. The 7% drop in intermodal volume drove a 4% decline in overall traffic as NS lost container business to rival CSX, which launched an intermodal alliance with BNSF Railway last summer. The adjusted operating ratio was 65.3%. For the full year, overall NS volume was flat. The railroad’s operating income was up 7%, to $4.4 billion, but was up 3% on when adjusted for one-time items.