UP 1507 (GP40N) runs into the North Yard in Denver, Colorado.

UP 1507 (GP40M-2) has completed the transfer run to the BNSF Denver Yard and crosses the South Platte River as it heads back to the Union Pacific's North Yard.

UP 1507 (GP40M-2) heads back to the tie down area after a day of working the North Yard in Denver, Colorado.

A quartet of light power sits in the North Yard in Denver, Colorado as they wait for their shift to shuffle cars.

UP 1507 (GP40-2) sits in the Union Pacific's North Yard as UP Big Boy 4014 backs towards the freight cars that it will take to Cheyenne, Wyoming.

UP 1507 (GP40M-2) works a cut of cars into the ladders deep in the North Yard in Denver, Colorado.

UP 1507 (GP40M-2) works the North Yard sorting freight cars into the various ladders.

A mix of light and heavy power wait in the Union Pacific's north yard in Denver, Colorado.

UP 1507 (GP40M-2) sits with other light power in the North Yard in Denver, Colorado.

UP 1507 GP40M heads in from the yard after a day or sorting cars in the Union Pacific's North Yard.

It is an active day in the Union Pacific's North Yard in Denver, Colorado.

UP 1507 (GP40M) passes the Union Pacific's operations building at the North Yard in Denver, Colorado.

Light snow falls on UP 1507 (SD40N) as it drops off a gondola at a recycling facility in Littleton, Colorado.

Snow is falling as UP 1507 (SD40N) crosses Santa Fe Drive in Englewood, Colorado, taking with it a gondola and a bay window caboose.

UP 1507 (GP40M) moves through the Union Pacific's North Yard in Denver, Colorado.