I know there is a certain suspension of disbelief required for most TV dramas, but as a railroad buff I can tell you that the train scene before it was derailed by the tank was pure hogwash. That was a steam engine, apparently done in CG to look like one from the Pennsylvania Railroad which never operated west of Illinois. Not to say that a museum couldn't have one, but bringing one back to life takes years if not decades.
Since I had just caught up with the whole series thanks to Universal HD's marathon session over the weekend, I was also aghast at the way the other train in the series was portrayed. Supposedly, Gracie (the old grocery store owner that was eventually murdered) was expecting a delivery by train of fresh goods, and her young helper (later a land baron) walked out on the railroad tracks to find the train abandoned after it had struck a car that was crumpled up on its front. He goes back and finds a boxcar load of food, presumably most of it non-perishable. You later learn he made the "15 mile" trip every day for some time to re-stock her store.
Railroads gave up carrying LCL (Less than Car Load) freight in the 1950's and 60's. And what you had with this train was a short line operation by the looks of the engine. If there were any boxcars, they might have been filled with paper rolls. Freight railroads mostly move bulk goods like coal, grain, and lumber. A mainline road with intermodal containers might have food products in some containers, but it is not a major commodity carried in this venue. There are refrigerated cars that do carry perishable items, but again you see them on mainline routes and not short lines.
What they could have used such a locomotive for was power generation. Older diesel-electric engines do not have much in the way of electronics to fry in an EMP pulse. If the railroad ran through Jericho, surely the bright ones in this story could have figured out a way to move it into town and rig it to take the 600VDC from the main generator to invert it to 240/120AC. Heck, in a town that size they surely had a retired railroader to tap!
But I digress. The series is full of other holes that I won't go into. Yet somehow, it's still fun to watch!
sigmtr