It is a common sight on the BNSF (ex FWD) line between Wichita Falls and Fort Worth Texas, to see loaded 11,0000 ton coal trains (100 cars @ 110 tons each) with three units, two in the front and one in the rear, or sometimes four units (two in front and rear). These locomotives are most often SD70's of some flavor, so the trains are powered by 12,900 hp if 3 units, or 17,200 horesepower if four. The trains usually return empty via the reverse route, and the consists are left intact, though sometimes they travel without being turned, so one might see an empty of 100 cars with a single unit in the front, and two in the rear. Often on an empty the two units in the rear are not operating, but instead "going along for the ride". They can be started remotely, though, if needed.
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