a group of geek goes to Shortline railroad, the Coopersville and Marne Railway, a very small shortline railroad having two locomotives, all are yard switchers but only one. the EMD SW9 does the tourist passenger train.
http://www.youtube.com/watch?v=y7d7t_4dZko
there you can also see Conrail boxcar. but this railroad doesn't seems to haul freights. yep the video doesn't say how multiple unit operations of diesel electrics work? yet I know that in any given Class 1 Freight trains in North America, there were hauled by a set of 4 locomotives, but only one engine is manned. Is there any connecting device needed in order to achieve multiple unit operations? does SW9 has any?