Hi Ted. Am not sure if we have the original plans, someone else can answer that question. We do have photographs.
I do know original Wiscasset roundhouse had three tracks. When you stand on the turntable and look at the roundhouse the original roundhouse had the run thou track on the left hand track. The museum will build the new roundhouse with the run thou track on the right hand track. This track is in service at the present time, it runs from the North Yard.