PRLX 4102 (SD40-2) sorts a stack train in the yard at Hudson, Colorado.

BNSF ACe 8571 runs towards Denver on the Brush Sub through Commerce City, Colorado.

BNSF 3005 (GP40) works the track under Interstate 70 in Denver, Colorado.

The California Zephyr runs through Tunnel #12 in South Draw, Colorado, pulling a private car on its way to Denver's Union Station.

UP 1359 (GP40-2) works the intermodal facility in the 36th Street Yard, passing an apartment building built to look like an ant colony structure.

BNSF 5873 (ES44AC) leads a string of auto racks through Commerce City, Colorado on its way to Denver on the Brush Sub.

BNSF 8571 (SD70ACe) runs past a refinery in Commerce City, Colorado.

BNSF Executive Grinstein #9819 (SD70MAC) sits with the other pumpkins at the depot in Longmont, Colorado waiting for orders.

BNSF 8596 (SD70ACe) leads a loaded coal train past the petroleum refineries in Commerce City, Colorado.

UPY 618 (GP15-1) runs long hood forward and repositions a couple of tank cars in the yard in Commerce City, Colorado.

A triple headed lash-up, including UP 1359 (GP40-2), sorts empty container cars in the Union Pacific's 36th Street Yard in Denver, Colorado.

UP 1359 (GP40-2) moves a stack train in the 36th Street Yard in Denver, Colorado.

UP 7788 (ES44AC) leads a freight into Laramie, Wyoming.

BNSF 6359 (ES44AC) joins a warbonnet and third pumpkin as they wait on the ready track in the Union Pacific's North Yard in Denver, Colorado.

BNSF 6190 (ES44AC) leads a loaded coal train on the Joint Line through Greenland, Colorado.