It's just after sunset with temperatures close to zero as Amtrak train no. 6, the California Zephyr, wastes no time descending the grade at Coal Creek Canyon during the cold blue hour.

Amtrak eastbound California Zephyr swings through a curve east of Radium, Colorado, on August 4, 2014.

Amtrak’s “Phase I Heritage” locomotive, GE P42DC No. 156, leads the eastbound California Zephyr down the Front Range of the Rockies west of Rocky, Colorado, on the afternoon of June 1, 2014.... (more)

Tunnel 40—all 63 feet
Amtrak No. 6, the eastbound California Zephyr, curves along the Colorado River through Tunnel 40 in Little Gore Canyon west of Azure, Colorado, on August 21, 201... (more)

The colorful neon light tail sign of Chicago, Burlington and Quincy California Zephyr dome-observation “Silver Solarium” glows on the evening of October 15, 2014, at Denver, Colorado.

Amtrak P42 #11 is seen leading the westbound California Zephyr #5 at Tolland - 19/09/2014

Amtrak P42 #60 and P40 #816 are seen leading the westbounde California Zeprhyr #5 west at State Bridge with a FRA car at the front perhaps why its running to time!? - 07/10/2014

Amtrak P40s 821 and 823 are seen leading the eastbound California Zephyr #6 at Parshall - 07/10/2014

Minutes after the sun went away, running over eight and a half hours late, Amtrak #5, the California Zephyr climbs the 2% grade through Coal Creek Canyon up towards Tunnel #1.

Amtrak No. 6, the eastbound California Zephyr, cruises downgrade through Clay, Colorado, on the afternoon of August 18, 2010. Waiting down below at Rocky siding for the passenger train’s passing... (more)

The calendar says spring, but the weather says winter at Crescent, Colorado, on April 23, 1999. Amtrak No. 5, the California Zephyr, climbs the Front Range of the Rockies through a snowy wonderlan... (more)

About to enter Tunnel 39 and Little Gore Canyon, Amtrak No. 5, the westbound California Zephyr, is west of Azure, Colorado, along the Colorado River on August 20, 2014.

Approaching Big 10 Curve is Amtrak No. 5, the westbound California Zephyr, west of Rocky, Colorado, on October 11, 1999. Powering the train are GE P42DC Nos. 30 and 67, with EMD F40PH No. 259 thro... (more)

Stainless steel smile
Amtrak No. 5, the westbound California Zephyr, curves into a smile as seen from high above Tunnel 40 in Little Gore Canyon west of Azure, Colorado, on August 21, 2... (more)

The crew secures a cable knocked lose by snow and ice. Photo taken with permission and necessary PPE.