A snowstorm catches UP 1817 (SD40N) and mates waiting in the UP's North Yard.

UP 1817 (SD40N) brings a train into the North Yard in Denver, Colorado.

UP 1997 is one of many SD40N units currently found working the large North Yard in Denver, Colorado.

The bright sun and the snow really makes the Amour Yellow pop on the motors in the Union Pacific's North Yard.

A quartet of light power, including UP 1817 (SD40N) wait in the Union Pacific's North Yard in Denver, Colorado for their turn at sorting freight.

A group of light power sits in the Union Pacific's North Yard waiting for assignments.

The Union Pacific utilized quite a few rebuilt SD40N's (former SD40-2's) to shuffle freight cars in the North Yard in Denver, Colorado.

UP 1640 SD40N sorts oil cans in the North Yard as a pair of BNSF motors arrange a stack track in the adjacent intermodal facility.

UP 1826 (SD40N) moves a center beam car to a lumber distribution company in the UP's North Yard.

UP 1826 (SD40N) moves a cut through the North Yard in Denver, Colorado.

UP 1640 is one of many SD40N units that can be currently found working the North Yard in Denver.

UP 1865 (SD40N) shuffles cars in the North Yard in Denver, Colorado.

UP 1865 (a SD40-2 rebuilt as a SD40N) sits in the Union Pacific's North Yard in Denver, Colorado.

UP 1865 (SD40N) joins other light power in the Union Pacific's North Yard in Denver, Colorado.

UP 1905 (SD40N) runs long hood forward (backwards) with a MOW train at Speer, Colorado.