UP 1943 (SD70ACe) Runs under Highway 93 as it heads to Rocky, Colorado.

UP 5567 (AC4400CW-CTE) muscles a freight through Little Ten Curve at Rocky, Colorado.

An optical illusion makes it appear as though the Union Pacific oil train is running up an extra steep grade at Rocky, Colorado.

BNSF 9214 (SD70ACe) muscles the Denver to Provo train through Rocky, Colorado on the Moffat Tunnel Sub.

A Union Pacific loaded coal train is running through Arena (also known as Little Ten Curve) at Rocky, Colorado and will arrive in Denver within the hour.

Evidence of busting snow drifts on the Moffat coat the pilot on BNSF 5700 (ES44AC) as it leads a freight towards Denver, Colorado.

Eight GE and EMD locomotives are leading Union Pacific’s MNYRO westbound as it approaches Big 10 Curve between Rocky and Eisele, Colorado, on February 9, 2015.

The California Zephyr runs towards Big Ten Curve and will soon begin climbing towards the Moffat Tunnel.

The California Zephyr runs through Rocky, Colorado as it gets ready to climb through 29 tunnels on its way to the Continental Divide.

The California Zephyr runs through Little Ten Curve as it heads to Big Ten and the Colorado Rocky Mountains.

With the majestic Boulder, Colorado Flatirons in the background, the California Zephyr runs through Little Ten Curve at Rocky as it begins the journey up the Moffat Tunnel Sub.

The California Zephyr runs through Little Ten Curve at Rocky Colorado and begins the journey to the Moffat Tunnel.

Amtrak engine #134 (P42DC) leads the California Zephyr around Big Ten Curve as it runs past a line of ballast-filled coal cars that have been welded to an adjacent track as a wind break.

Rio Grande EMD GP40-2 Nos. 3126 and 3121 switch the aggregates plant at the end of Rocky Spur leaving the main line at Rocky, Colorado, on February 21, 2002. During this era, two or three Rio Gran... (more)

UP 5857 (AC4400CW-CTE) leads an oil train towards a waiting BNSF train at Rocky, Colorado.