U.S. rail shippers don't appear to be heeding the warnings of a national economic slowdown. Intermodal volume in May on the major U.S. railroads hit the highest level in history for that month, according to the Association of American Railroads. Intermodal traffic last month was 3.5 percent higher than the same month a year ago. Although carload volume was down 2.8 percent year-over-year in the same period, the big losses were because of slumps in the major commodities of coal and grain.

For those interested in transportation management, the news that truckload rates are trending flat for the time being may be good, although on a year-over-year basis, May's index registered 5.0 percent higher than for the same period last year. The continuing share shift toward intermodal is at least one reason rates are being held in check.

In international trade news, import cargo volume at the nation's major retail container ports is expected to increase 4.8 percent in June compared with the same month last year, and year-over-year increases are expected to continue into the holiday season shipping cycle, according to the monthly Global Port Tracker report released by the National Retail Federation and Hackett Associates.