UP 1598 (SD40-2 which has been rebuilt to a SD40N) is sorting a cut of hoppers while UP 5087 brings another train into the yard. If you look closely in the background you can see a BNSF train waiting for the inbound UP to cross the main track. Once cleared the BNSF freight will head to the Denver Yard in lower downtown.
The EMD SD (special duty) series are a strong and reliable kind of locomotive which still serve America's rails today. They have proved themselves reliable by clocking in several million miles of freight service.