An engine servicing facility for the JGL

[Lester Perry]

I think locomotives were also backed in to the roundhouse so that a minimum of smoke and soot would actually enter the roundhouse, but I may be mistaken on that count. The obvious exception to locomotives being backed in would be the Southern Pacific cab forwards since in reality they were designed to run "backwards."

Steam Locomotives were pulled in forward. There was a large ductwork for lack of a better term. That hung from the ceiling for the exhaust to exit the building Note there is a smoke stack for each track in most cases.
Les