I’ve seen this train on a couple Youtube webcams. There are specially painted tank cars, box cars and this. Not sure what this is.
It is Norfolk Southern’s Training First Responders trainset.
They are specially painted, and designed cars, that make up a mobile classroom to train fire, emergency medic, and police, on proper response to a incident involving a train, be it a grade crossing collision, engine fire, or derailment.
Interesting tidbit: A couple of years back, they were involved in an unintended grade crossing collision with this very trainset.