As the power of an eastbound Santa Fe 971 circles the Loop, its rear loads continue to enter the Loop on the approach below. The train is circling the famous landmark just as the sun is setting, and the scene is being recorded through a 500mm lens positioned at Woodford.
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 over several decades.