Westbound Union Pacific unit tank car train. Chicago Illinois. July 2007., a photo by Eddie from Chicago on Flickr.
I took this photograph during a hot summer 90 degrees Farenheight outside plus morning, back in July of 2007.
Approaching the North Kilbourn Avenue railroad crossing along the Metra / Union Pacific west line mainline (Formerly C & N,W)
we see a westbound Union Pacific Railroad unit tank car freight train.
Notice the large covered hopper car coupled behind the locomotives. This train must be carrying some very flamable liquids, and the hopper car is proboubly doubling as a "Buffer Car" just in case of an explosion or derailment to protect the locomotive crew in transit.