AAR reported mixed rail traffic for the week ending Feb.9, 2013.  Last week U.S. railroads originated 273,369 carloads, down 2.3 percent compared with the same week last year, while intermodal volume for the week totaled 244,679 units, up 7.7 percent compared with the same week last year.  Total U.S. traffic for the week ending Feb.9 was 518,048 carloads and intermodal units, up 2.2 percent over the same week last year.  Six of the ten carload commodity groups posted increases compared with the same week in 2012, with petroleum products, up 65 percent, and nonmetallic minerals and products, up 14 percent. The groups showing a decrease in weekly traffic included grain, down 17.3 percent, and metallic ores and metals, down 13.5 percent. For the first six weeks of 2013, U.S. railroads reported cumulative volume of 1,612,973 carloads, down 5.7 percent from the same point last year, and 1,413,309 intermodal units, up 5.7 percent from last year. Total U.S. traffic for the first six weeks of 2013 was 3,026,282 carloads and intermodal units, down 0.7 percent from last year.  Canadian railroads reported 80,020 carloads for the week, up 3 percent compared with the same week last year, and 50,882 intermodal units, down 4.1 percent compared with 2012. For the first six weeks of 2013, Canadian railroads reported cumulative volume of 452,537 carloads, up 2 percent from the same point last year, and 302,113 intermodal units, up 4.4 percent from last year.  Mexican railroads reported 14,211 carloads for the week, up 7.9 percent compared with the same week last year, and 9,103 intermodal units, up 4.7 percent. Cumulative volume on Mexican railroads for the first six weeks of 2013 is 82,637 carloads, up 7 percent from the same point last year, and 52,642 intermodal units, down 2.2 percent from last year.