BNSF 5700 (AC4400CW) waits in the engine servicing yard for an assigned train.

UP 1502 (GP40-2) joins an eclectic group of engines waiting for servicing or orders in the Union Pacific's North Yard in Denver, Colorado.

Union Pacific GE AC4400CW No. 6433 has its third axle/traction motor assembly replaced, as it slowly is lowered in the drop pit and carefully watched by a machinist and an electrician. The locomot... (more)

A couple of GE locomotives are in for work over the drop pit in the Diesel House at Union Pacific’s Burnham Shops in Denver, Colorado, on December 16, 2015. UP GE AC4400CW No. 6344 is having its... (more)

A group of Union Pacific EMD and GE locomotives get repairs and inspections done inside the Diesel House at UP’s Burnham Shops in Denver, Colorado, on December 21, 2015. Unfortunately, UP closed... (more)

As afternoon storms bring on evening across the front range of Colorado, a northbound mixed fright departs Denver on UP’s Greeley Subdivision.

With a massive thunderstorm cell looming in the background, RTD 4030 (Hyundai Eagle) runs on the commuter rail line linking Denver International Airport with downtown Denver.

A large group of older Union Pacific EMD and GE six-axle locomotives sit stored at the railroad’s Burnham Shops facility in Denver, Colorado, on December 21, 2015.

Union Pacific EMD SD40N No. 1826 has some repair work done on the just above the big HTC truck in the Diesel Shop at the railroad’s Burnham Shops in Denver, Colorado, on December 17, 2015.

Amtrak 'Bumblebee 203' carries the Operation Lifesaver 50th Anniversary markings and was spotted this week in Denver, Colorado attending a convention on railroad safety.

Shades of the past. If you look closely, you will spot a few 'Old School' engines in the BNSF engine servicing facility, including a Warbonnet, two Cascade Green Burlington Northern units as an E... (more)

Union Pacific GE AC4400CW No. 6891 gets an inspection over the pits in the Diesel House at UP’s Burnham Shops in Denver, Colorado, on December 16, 2015.

UPY 625 (GP15-1) gathers a cut of freight cars in the UP's North Yard in Denver, Colorado.

A variety of engines wait in the Union Pacific's North Yard in Denver for assignments or servicing.

Amtrak engine 132 (P42DC) leads the California Zephyr through the Denver Yard and passed a Canadian Pacific engine waiting to head to a train.