Intermodal rail traffic in the U.S. keeps rising with a new record being set for January.

The Association of American Railroads reports for the first month of 2015 the number of intermodal containers and trailers moved by U.S. railroads averaged 251,267 units per week, the highest weekly average for January in rail industry history.

For the month combined U.S. rail carload and intermodal originations were up 3.4% over January 2014. The average of 541,477 combined units per week was the second highest for a January on record, behind only January 2006.

"January was a good start to the year for U.S. railroads, helped by the fact that the winter so far this year hasn't been nearly as bad as it was last year," said AAR Senior Vice President John T. Gray.

U.S. freight railroads also reported rail carloads in January were the highest for the month since January 2008.

For the week ending Jan. 31 AAR said U.S. weekly intermodal volume was up 1.1% compared to 2014. Total rail carloads and intermodal units were up 5.9% compared to the same week in 2014

North American rail volume for the week on 13 reporting U.S., Canadian and Mexican railroads was up 10.4% compared with the same week last year, and intermodal units alone were up 6% during the same time. North American rail volume for the first four weeks of 2015 was up 5% compared with 2014.