The rise of Distributed Power Units (DPUs) is quite evident--10 years ago, you rarely saw them, and only on interstate coal drags that crossed the Rockies. Now they're everywhere; grain shuttles, double stacks, coal drags, anything with lengthy--and heavy--loads.
Here, this lone SD9043MAC (UP #8225) serves as a DPU on the tail end of a unit coal drag, eastbound through Hays, KS.
Canon EOS 30D
Canon EF 70-200mm f/2.8 L IS USM
ISO 100 @ 1/400, f/6.3