BNSF 5908 (ES44AC) muscles an oil can train through Big Ten Curve at Rocky, Colorado, as it climbs the 2% grade of the Moffat Tunnel Sub.

BNSF 5908 (ES44AC) runs through Big Ten Curve on the Moffat Tunnel Sub.

The California Zephyr #6 train rounds the Big Ten Curve in Rocky, Colorado as it heads to Denver on the Moffat Tunnel Sub.

The Rocky Mountaineer passenger train has 4 engines running in a push me - pull you configuration as it takes a load of passengers on a short trip to Eisele, Colorado and then back to Denver.

The California Zephyr runs east on the Moffat Tunnel Sub towards Rocky, Colorado and will soon be backing into Denver's Union Station.

This view from the top of Blue Mountain gives a good view of the Big Ten Curve as the California Zephyr #6 train drops down the 2% grade towards Rocky, Colorado.

The lead engine on the California Zephyr looks like it's about to time travel as it runs through Rocky, Colorado on the Moffat Tunnel Sub towards Denver.

The California Zephyr passes maintenance equipment working on the Big Ten Curve in Rocky, Colorado.

BNSF 5146 (Dash9) rounds the Big Ten Curve at Rocky, Colorado as it heads down the 2% grade towards Denver.

The Rocky Mountaineer's blue SD40M-2 leads the train on a test run through Little Ten Curve at Rocky, Colorado.

The BNSF Provo train rounds Big Ten Curve as it transitions down the 2% grade of the Moffat Tunnel Sub at Rocky, Colorado.

I spy, with my tree eye, Amtrak's OLI, passing by.

The California Zephyr runs through the open prairie lands of Rocky, Colorado as it heads into the Colorado Mountains on the Moffat Tunnel Sub.

Rocky Mountaineer's 8600 (SD40M-2) runs towards Big Ten Curve at Rocky, Colorado.

Here is a good profile look of Rocky Mountaineer's GP40-3 that runs on point through the Big Ten Curve in Rocky, Colorado.