Actually, it makes good sense.
- These locomotives have low-speed control built right into the design, not add-ons as are used on conventional locomotives commonly used in hump service. SD70MACs were designed to operate at a constant low speed for flood loading of coal trains at the mine tipple, and for dumping at the delivery pit. They compensate for the train weight increasing or decreasing, and continue to maintain constant speed. This is ideal for humping.
- Two SD70MACs are powerful enough to hump a complete train, without having to reduce it to two or more cuts.
- Many -- if not all -- of the SD70MACs are fully-amortized.
- Coal traffic is down and unlikely to return to former levels; these locomotives are available. Utilizing them in hump service is far preferable to storing them. Storing less efficient locomotives, and keeping the MACs working makes good financial sense.
These are "one-owner" locomotives, well-suited for hump service and for other service.
