A trio of BNSF engines pay a visit to the Union Pacific's North Yard in Denver, Colorado.

A trio of BNSF engines sit in the Union Pacific's North Yard in Denver, Colorado.

The Rocky Mountaineer Railtours engines sit in the Union Pacific's 36th Street Yard in Denver, Colorado, waiting for light maintenance.

New to the database is UP 1730, an ex-Missouri Pacific GP15AC built in 1982.

UP 1826 (SD40N) moves a cut of hoppers for sorting in the Union Pacific's North Yard in Denver, Colorado.

UP 7900 (ES44AC) leads a coal train into the Union Pacific's 36th Street Yard in Denver, Colorado.

UP 1826 (SD40N) passes three BNSF motors that are sitting in the Union Pacific's North Yard in Denver, Colorado.

BNSF 7147 (ES44C4) passes under the RTD Commuter Rail line that runs out to Thornton, Colorado.

BNSF 1899 (SD40-2) leads a freight towards Denver, Colorado on the Brush Sub.

Light power dominates the Union Pacific North Yard in Denver, Colorado.

Its' Throwback Thursday at the BNSF engine servicing facility as 1656 (SD40-2) waits for service or assignment.

UP Y625 (GP15-1) sports a unique shark-mouth pilot blade as it sits in the Union Pacific's North Yard in Denver, Colorado.

UP 1980 (GP38N) waits in the Union Pacific's North Yard in Denver, Colorado for service at the fuel islands.

UP 1507 (GP40M) is entering the BNSF's Denver Yard with a cut of freight cars and will head back to the UP North Yard after dropping off the cars.

UP 1507 (GP40M) moves a cut of cars early in the morning in the Union Pacific's North Yard in Denver, Colorado.