U.S. freight carload traffic rose 1.5% in the week ending January 22, compared with the third week of 2010, the Association of American Railroads said Thursday, categorizing the advance as “modest.” U.S. intermodal traffic growth was slightly more robuts, up 6.2% for the week compared with last year.

Eleven of the 20 carload commodity groups measured by AAR saw increases from the comparable week in 2010. Leading gainers included: metallic ores, up 48.1%, and metals and products, up 20.6%. Among declining categories, nonmetallic minerals fell 18%, while waste and nonferrous scrap declined 16.6%.

Canadian freight carload traffic dropped significantly for the week ended January 22, down 10.1% compared with the same week in 2010. Canadian intermodal traffi, however, advanced 3.2% compared with last year. Mexican freight carload traffic mirrored the U.S., up 1.7%, while Mexican intermodal slipped 2.6%.

Combined North American rail volume for the first three weeks of 2011 on 13 reporting U.S., Canadian, and Mexican railroads was down 0.8% measured agains the comparable period in 2010. Intermodal was up 5.4% compared with last year.

The Association of American Railroads Tuesday said 2010 saw U.S. freight carload traffic in 2010 rose 7.3%, to 14.8 million total carloads, compared with 13.8 million carloads in 2009. Total U.S. annual intermodal traffic in 2010 increased 14.2%, with 11.3 million total truck trailers and shipping containers, compared with 9.9 million trailers and containers in 2009.

As it did throughout 2010, AAR reiterated its warning that 2009’s baseline was extraordinarily load, adding that “2010 still saw the second lowest total annual carloads on record, behind 2009.” AAR began its data series in 1988.

“Like the economy in general, rail traffic in 2010 recovered some lost ground, but not nearly all of it,” said AAR Senior Vice President John T. Gray. “That being said, monthly rail traffic increases were broadbased, supporting the idea that economic recovery likewise is broad-based.”

Carload freight in December 2010 was up 9.4% from December 2009 levels, while intermodal traffic for the month was up 13.3%.

All of the 19 commodity categories tracked by AAR saw carload increases in 2010 compared with the prior year. However, all categories were still down compared with 2008. During 2010, coal accounted for 45.4% of all U.S. carload traffic, down from the all-time high of 48.2% in 2009. Chemicals came in a distant second, representing 10.1% of all carloads, followed by grain at 7.8%.

Containers led the U.S. intermodal traffic segment in 2010, with a record high of 84.9% of intermodal traffic, up from 83.4% in 2009.

AAR said railroads continued to bring employees back to work and cars out of storage last year. As of Jan. 1, 2011, railroads had 316,271 cars in storage, representing roughly 20.8% of the North American railcar fleet. That means railroads last year brought 132,284 cars out of storage. As of November 2010, the most recent month for rail employment data, the nation’s major Class I railroads employed 155,042 people, up nearly 8,000 employees from November 2009.