An eastbound Union Pacific coal train approaches Blue Mountain Drive grade crossing west of Clay, Colorado, on December 22, 2006. Leading the train is UP GE AC4400CW No. 6734, formerly Chicago & ... (more)

Two DPU sets trail a loaded Union Pacific coal train down the 2-percent grade out of Tunnel 1 between Plain and Clay, Colorado, on a snowy December 22, 2006. The mid-train DPU made up of two EMD S... (more)

Snow-covered scenery at the mouth of Coal Creek Canyon provides a wintery backdrop for Union Pacific's freight MRONY approaching Blue Mountain grade crossing west of Clay, Colorado, on the spring ... (more)

A pair of UP ES44AC's shove the rear of an empty coal train around Big 10 Curve in Clay, CO.

Below, a westbound Union Pacific freight waits in the siding at Rocky, Colorado, while an eastbound BNSF manifest freight above cruises through Clay on February 23, 2011. The trains are separated ... (more)

Six Union Pacific GE AC4400CW/AC4400CW-CTEs lead a westbound coal empty through Clay, Colorado, on the afternoon of June 25, 2011. Above the second locomotive in the distance is Big 10 Curve, and ... (more)

A Union Pacific coal empty climbs through a snowy Clay, Colorado, on February 10, 2001. Powering the westbound train is a Southern Pacific GE AC4400CW and two UP EMD SD9043MACs.

A Union Pacific freight approaches Blue Mountain Drive grade crossing west of Clay, Colorado, on April 14, 2001. Three EMD SD40T-2s and a UP GE AC4400CW power the westbound train, with Rio Grande ... (more)

On Colorado’s Front Range on the afternoon of April 30, 2001, Union Pacific’s MDVRO (Denver to Roper Yard in Salt Lake City) manifest freight heads into Clay siding for a meet with Amtrak No. ... (more)

Union Pacific MDVRO (Denver to Roper Yard in Salt Lake City) freight leaves the great plains behind as it curves out of Clay, Colorado, on April 18, 2001. Eight locomotives power the westbound tra... (more)

Union Pacific’s MDVRO manifest freight is westbound crossing Blue Mountain Drive grade crossing west of Clay, Colorado, on September 20, 2001. UP EMD SD60 No. 2235 leads Southern Pacific SD40M-2... (more)

Union Pacific GE AC4400CW-CTE No. 6065 leads a westbound coal empty west of Clay, Colorado, on December 29, 2006.

Union Pacific’s Denver to Phippsburg manifest freight climbs through Big 10 Curve at Clay, Colorado, on a sunny October 23, 2011.

Union Pacific’s former Rio Grande main line west of Denver attacks the Front Range of the Rockies directly using a 2% grade and numerous curves and tunnels to “make the grade.” After looping... (more)

Descending the Front Range of the Rocky Mountains between Clay and Rocky, Colorado, is a Burlington Northern Santa Fe coal train on Union Pacific’s Moffat Tunnel Subdivision, on June 18, 2001. T... (more)