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.
Having conquered the Big 10 Loops, this BNSF freight train is about to cross the Blue Mountain Road as it continues the strenuous climb out of Denver and into the Rockies.
Heading through light snow flurries and with a temperature of 1 degree outside, the M-K-T Heritage engine approaches Denver leading this Eastbound manifest train.
With the temperature close to zero, Amtrak train no. 6, the California Zephyr descends the grade at Big Ten Curve with the Denver Metro area in the background.