A group of SD40's hold station in the Union Pacific's North Yard in Denver, Colorado.

BNSF 7799 (ES44DC) leads the Coors beer train from Denver and will soon arrive in Golden, Colorado.

BNSF 1746 (SD40-2) works sorting a cut of cars in the Denver Yard.

UP 1640 (SD40N) works the North Yard in Denver, Colorado.

The Amtrak Winter Park Express Ski Train rounds the corner in the North Yard as it takes a load of skiers from Denver to the Winter Park ski resort.

UP 5587 (AC4400CW-CTE) leads a freight over the belt line towards the 36th Street Yard in Denver, Colorado.

UP 1357 was built in 1972 for the Denver & Rio Grande Western as a GP40-2. It now works the North Yard in Denver, Colorado.

Thunderstorms have just moved through the North Yard in Denver, Colorado as UP 1212 (GP39-2) works on a cut of cars.

UP 1997 (SD40N) moves through the North Yard in Denver, Colorado.

UP 1997 (SD40N) reflects off a puddle in the North Yard in Denver, Colorado.

UP GP40X and Amtrak 321 and 322 depart Denver Union Terminal with the westbound San Francisco Zephyr.

RTD Commuter Train #4049 (Hyundai Eagle P3) takes the elevated track as a UP freight runs on the lower track towards the 36th Street Yard.

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

Amtrak engine #45 (P42DC) leads the Winter Park Express west on the Moffat Tunnel Sub at sunrise.

BNSF 1746 (SD40-2) sort a string of cars in the yard in downtown Denver, Colorado.