A manned helper set of four Montana Rail Link EMD SD70ACes are cut into a heavy coal train working up the steep 2.2% grade grade up Mullan Pass west of Helena at Skyline, Montana, on the morning of June 29, 2017.
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.
