Intermodal rail traffic fell in February, according to new figures released on Wednesday by the Association of American Railroads.

U.S. railroads originated 929,395 containers and trailers during the month, down 6.5%, or 64,384 units, from the same month last year. For February 2015, combined U.S. rail carload and intermodal originations were 2,018,606, down 76,110 units, or 3.6%, from February 2014.

"The problems at West Coast ports clearly had an impact on rail traffic in February. Bad weather in the East and Midwest didn't help," said AAR Senior Vice President John T. Gray. "It's not possible to quantify the impact of these factors precisely. However, economic fundamentals remain mostly positive, so railroads are expecting significant traffic improvements in March."

A tentative agreement between West Coast port workers and shipping companies was reached on Feb 20, after it expired many months earlier, leading to work slowdowns and freight piling up at marine ports that will still take weeks to clear out.

For the first eight weeks of 2015, the number of intermodal containers and trailers moved by railroads totaled 1,934,462 units, down 55,726, or 2.8%, when compared to the same period in 2014. Total rail traffic volume during the same time span in the U.S. was 4,184,515 carloads and intermodal units, down 5,588, or 0.1%, from the same time last year.

For the week ending Feb. 28, intermodal rail volume was 241,598 containers and trailers, down 6.3% compared to 2014. Total U.S. weekly rail traffic for the week was 508,658 carloads and intermodal units, down 6.7 % compared with the same week last year.

North American rail volume for the week ending Feb. 28, on 13 reporting U.S., Canadian and Mexican railroads totaled 360,582 carloads, down 3.9% compared with the same week last year, and 309,091 intermodal units, down 4.3%. In contrast, North American rail volume for the first eight weeks of 2015 was 5,470,264 carloads and intermodal units, up 1.6% compared with 2014.

Last week Canadian railroads moved 56,430 intermodal units, up 4% compared with the same week in 2014 while Mexican railroads transported 11,063 intermodal units, up 2.1%.