Round Pole Building

We get some interesting shed-related mail from time-to-time. This note from Jim poses that age-old question ... how much will it cost to build this structure? But Jim's request is rather unique. He needs to determine the costs for construction and materials on a railroad roundhouse pole barn...

Jim wrote:

We're looking at building a semi circular railroad roundhouse with 72' side walls. Each two track roundhouse stall measures 32' wide on the front wall and 48' wide on the rear wall. There will be thirteen of these sections to create the roundhouse for our railroad museum. We are trying to estimate the cost for a pole type building and the reason for that is that the pole type building is closest to the original construction.

They say the devil's in the details. What type of siding on that pole barn? What kind of roofing? While I'm not the one to calculate construction costs on such a unique structure, I'll bet there's a reader (or a pole building company) out there that can pitch in with a rough estimate ...