Hudson Terminal Railroad's veteran Alco S1 shoves a cut of oil cans in the yard in Hudson, Colorado.

Eighty-year-old HTR 646 (Alco S1) moves into the yard in Hudson, Colorado and will spend the next few hours sorting tank cars.

Hudson Terminal Railroad's Alco S1 was built in 1946 and now works the yard in Hudson, Colorado.

Hudson Terminal Railroad's 80-year-old Alco S1 works the yard as storm clouds develop in the background.

Hudson Terminal Railroad's Alco S1 works a cut of oil cans in the large yard in Hudson, Colorado.

Hudson Terminal Railroad's #646 (Alco S1) moves a cut of hoppers towards the main track to be picked up by the BNSF at the terminal in Hudson, Colorado.

Hudson Terminal Railroad's veteran Alco S1 moves a cut of oil can in the large yard in Hudson, Colorado.

The yard team helps Hudson Terminal Railroad's 646 (Alco S1) change tracks at Hudson, Colorado.

Hudson Terminal Railroad's #646 (Alco S1) moves a cut of oil cans in the large yard in Hudson, Colorado.

Hudson Terminal Railroad's Alco S1 passes a pair of BNSF motors waiting to take a cut of oil cans from the terminal to Denver, Colorado.

Hudson Terminal Railroad's 79 year old Alco S1 moves a cut of sand hoppers through the yard in Hudson, Colorado.

Hudson Terminal Railroad's #646 will turn 80 years old this year, having been built in 1946 for the Detroit & Mackinac Railroad. You can find it working the oil can terminal in Hudson, Colorado. ... (more)

The 79 year-old Alco S1 of the Hudson Terminal Railroad (built in 1946 for the Detroit & Mackinac Railroad) passes a pair of vintage heavy weight passenger cars as it moves through the yard.

Hudson Terminal Railroad's Alco S1 moves through the yard as a BNSF train backs a cut of oil cans into a siding at the Hudson facility.

Hudson Terminal Railroad's vintage Alco S1 heads to a string of oil cans in the larger terminal in Hudson, Colorado.