I found this photo at My Link page Fallen Flags.Org, located to the right of Your computer screen.

One Chicago railroad that I have many happy memories lineside railfanning during the 1980's, was the former Burlington Northern Railroad. I can recall spending time along the busy three track Chicago to Aurora Illinois commuter mainline, and taking railfan photos and silent 8 MM home movies on location at places like Cicero Avenue, Berwyn, Riverside, La Grange, Western Springs and Downers Grove Illinois. I had spent the most time in west suburban La Grange Illinois back then.

This photo was taken at the Burlington Northern Clyde Yard enginehouse and locomotive terminal alongside West 31st Street, in west suburban Cicero Illinois during 1989. The locomotive, is a former Chicago, Burlington & Quincy ( Pre 1970.)
EMD model GP 9 roadswitcher, that was equipped with roof mounted air tanks for passenger train operation during the 1950's and 60's era. In passenger train operation back then, locomotive's carried a steam boiler for passenger car "Hotel Power" -Heat, Electricity and Air Conditioning. The air tanks had no room in their normal locattion because of htis, and had to be moved to the locomotive roof top.

These freight engines that were modified for dual service applications with the air tanks on the roof, were refered to as "Torpedo Tube EMD GP 9's, as they looked like the Torpedo missiles used on U.S Navy Submarines.