As a Union Pacific coal train rolls eastbound through Rocky, Colorado, in the foreground, a following eastbound BNSF freight departs Plain and is about to enter Tunnel 1 in the background on Augus... (more)

A pair of EMD Demonstrator engines bring this loaded coal train Eastbound heading into Denver. The cars in the background are for the wind break on the Big Ten curve.

Looking up toward Big 10 Curve at Rocky, Colorado, sees a Burlington Northern Santa Fe train hauling coal eastbound descending the front range of the Rocky Mountains at Rocky, Colorado, on June 18... (more)

A Burlington Northern Santa Fe train hauling coal eastbound on Union Pacific’s Moffat Tunnel Subdivision descends the front range of the Rocky Mountains at Rocky, Colorado, on June 18, 2001. On ... (more)

UP 8763 pulling east through Big 10

Colorado is blanketed with a fresh snow and there is a cold air inversion at lower elevations on February 2, 2014, as Union Pacific’s Denver to Salt Lake City manifest freight passes through Roc... (more)

With downtown Denver covered in cloud shadows in the background, a westbound Union Pacific freight curves through “Little 10 Curve” at Rocky, Colorado, on May 13, 2017. This lesser known curve... (more)

As a westbound Union Pacific Public Service (Xcel Energy) coal train climbs out of Rocky, Colorado, a view downgrade from near Big 10 Curve show two rear DPU locomotives pushing on the rear of the... (more)

UP 7815 heads West at Rocky siding past some MOW equipment with an empty coal train.

A pair of Tunnel Motors and a SD45 head East at Rocky with coal destined for the Arapahoe Power plant in Denver. This train ran shorter than most coal trains and was interchanged to the BN at Denv... (more)

A westbound Burlington Northern Santa Fe manifest freight works upgrade west of Rocky, Colorado, over the former Rio Grande main line on May 17, 2003. Three GE C44-9Ws power the train, assisted by... (more)

An eastbound Burlington Northern Santa Fe manifest freight leans into a curve departing Rocky, Colorado, on August 13, 2003. BNSF “warbonnet” GE C44-9W No. 4715 leads a C&NW AC4400CW, Santa Fe... (more)

Westbound Union Pacific MNYRO approaches Big 10 Curve west of Rocky, Colorado, on the morning of August 11, 2015.

Amtrak’s California Zephyr is climbing the two percent grade westbound toward Big 10 Curve west of Rocky, Colorado, on September 6, 2001.

Union Pacific manifest freight MRONY descends through Big 10 Curve west of Rocky, Colorado, on November 17, 2014.