Maybe everyone already knows this and I am late to the party, but I just discovered a site for scale model plans and on this link if you scroll down there are plans for a New Haven Roundhouse
https://www.scalemodelplans.com/smp/pgs ... #Trackside here is the description;
Plan 1438 - New Haven Railroad Engine house
PDF Plan package: $9.95
The New York, New Haven & Hartford Railroad, sometimes referred to as just New Haven Railroad, was a consolidation of several smaller railroads in the Northeastern United States during the late 1800's.
This engine house, on the New Haven "Wrentham Line" half way between Boston, Massachusetts and Providence Rhode Island, operated from 1892 to 1938. Although it still stands today, it now serves only as a storage warehouse.
This N Scale version is constructed with balsa covered in printed brick paper, with windows from Northeastern Scale Lumber Co. The modular plans allow for anywhere from one to over twelve bays, depending on your available space. (*includes 'photo-texture' cardstock sheets)
Download plans in either N, HO, OO, or O Scale