With the Boulder Flatirons in the background, a UP crewman walks back to his motor as BNSF 6012 (ES44AC) passes and heads up the Moffat Tunnel Sub.

UP 6454 AC4400CW leads an officer's special down the hill into Coal Creek Canyon, Colorado as it heads to Denver.

UP 6454 AC4400CW exits Tunnel #1 at Plainview, Colorado and will drop down into Coal Creek Canyon.

UP 6789 (AC4400CW) meets a BNSF coal train at Plainview, Colorado.

UP 6789 (AC4400CW) waits on a siding at Plainview, Colorado for a BNSF coal train which will be passing shortly.

UP 5889 (AC4400CW-CTE) leads a coal train up to Tunnel #1 at Plainview, Colorado as it heads west on the Moffat Tunnel Sub.

AMTK 135 (P42DC) leads the California Zephyr down the hill into Coal Creek Canyon as it heads to Denver, Colorado.

The California Zephyr runs between tunnels 3 and 4 as it begins the climb up the Moffat Tunnel Sub to the Continental Divide.

The sounds of GE motors echo through Coal Creek Canyon as they work their train out of the Big 10 Loops and up the grade around Plainview, CO on Union Pacific’s iconic Moffat Tunnel Subdivision.... (more)

The California Zephyr exits Tunnel 4 as it runs west on the Moffat Tunnel Sub at Plainview, Colorado.

The California Zephyr runs over the fill at Tunnel 2 at Plainview, Colorado.

The California Zephyr runs through Plainview, Colorado as it begins the climb into the Moffat Tunnel District.

The California Zephyr has exited Tunnel #1 and begins the climb up the Moffat Tunnel Sub that will take them through 29 tunnels to get to the west side of the Continental Divide.

AMTK 164 (P42DC) exits Tunnel #1 at Plainview Colorado.

UP 8243 (ES44AC) gets ready to leads a freight into Tunnel #1 at Plainview, Colorado.