Has anyone ever modeled tunnel exhaust vents? I am thinking of building a tunnel module and would like to feature a vent or two . It would be pretty cool considering all of the smoking going on in the O-gauge world. The DL&W built two large bunker like structures on top of their Factoryville PA tunnel (near the famous Tunkhannock viaduct). They are about 40 ft. square and I guessing 15 ft. tall and made of ubiquitous Lackawanna concrete. They still serve the NS today. If you have already modeled these cool features please share.
Thanks
Earl