The AAR said this week that the nation’s railroads carried 1,152,174 carloads in September, down 3.7%, or 43,746 carloads, over September 2011.

Intermodal traffic during the same period totaled 973,715 containers and trailers, a 2.5% increase over the same period last year, equal to 24,126 units; September 2012 was the 34th straight month of intermodal gains.

Of the 20 carload commodity groups reported by the AAR, 14 posted increases year-on-year including petroleum products (59%) and iron and steel scrap (16.6%),

Unfortunately, coal was among those showing a weekly traffic decrease of 17.3%. Metallic ores were down 19.6% and waste and nonferrous scrap were down 11.3%.

The AAR also noted that carloads excluding coal were up 3.4% percent, or 22,121 carloads, in September.

“September rail traffic is again a mix of good news and bad news,” senior vice president John Gray said.

“The primary bad news is that coal carloads continue to struggle, due to the various economic and regulatory constraints faced by coal-fired power plants. The good news is that many other key rail traffic categories are offsetting coal’s decline, including petroleum and petroleum products, motor vehicles, crushed stone and sand, and lumber.

“Intermodal volume has risen for 34 straight months and could very well set a new record this year.”

The group’s data also revealed that combined rail volumes for North America for the first 39 weeks of the year on 13 reporting US, Canadian and Mexican railroads totaled 14,606,519 carloads, down 1.4% versus with the same point last year; trailers and containers totaled 11,592,345, up 4.6 percent% compared to 2011’s figures.