Union Pacific ACe 8850 leads a freight down the Moffat line, passing Blue Mountain before taking the Big and Little Ten Curves.

UP 8850 (SD70ACe) leads a freight down the Moffat Tunnel Sub as it rounds Blue Mountain at Eisele, Colorado.

The California Zephyr passes through Eisele as it heads towards Blue Mountain on its way up the Moffat Tunnel Sub. Note the two private Patrick Henry Productions cars on the end.

The California Zephyr exits tunnel 2 and heads towards tunnel 3 on the Moffat Tunnel Sub.

The California Zephyr runs west on the high ridge at Eisele while a BNSF coal train waits for a crew at Rocky, Colorado.

The California Zephyr is pulling three private cars as it runs through Eisele, Colorado on its way towards the Moffat Tunnel.

The California Zephyr rounds the Big Ten Curve as it heads towards Blue Mountain and Coal Creek Canyon on the Moffat Tunnel Sub.

The Rocky Mountaineer passenger train glides down from Big Ten Curve as it transitions from the Colorado Rocky Mountains to the Front Range Foothills on its way to Denver, Colorado.

The evening California Zephyr is framed by the trees on top of Blue Mountain.

The venerable GE P42DC 'Genesis' engine has been a hallmark of Amtrak power since it went into production in 1992. In the 9 year production run 321 engines were built for Amtrak. A new engine from... (more)

This view takes in the Denver Skyline and the Big Ten Curve as BNSF 7068 (ES44C4) leads a long freight down the Moffat Tunnel Sub at Eisele, Colorado.

The California Zephyr runs through Eisele, Colorado (also known as Clay) which is at the base of Blue Mountain.

This shot gives you a good idea of how steep the grade is as the BNSF freight passes through Little Ten and Big Ten Curves and heads towards Eisele, Colorado. The head of the train is passing by ... (more)

With the Flatiron rock formations above Boulder, Colorado, in the background, Union Pacific’s MRONY manifest freight from Salt Lake City to Denver drops downgrade at Eisele, Colorado, on the aft... (more)

An empty BNSF sand train heads downgrade at mile 22.6 at the mouth of Coal Creek Canyon west of Eisele (Clay), Colorado, on December 19, 2017. The train is powered by a pair of GE locomotives, wit... (more)