@rplst8 posted:It is totally valid. They're dimensions in different scales. If I want to craft the same building in HO or O you take the HO dimensions, multiply by 87.5 then divide by 48. Same goes for building the same track plan.
I disagree. Look at this way. If you lay two 48 inch straight sections of HO and O gauge track side by side, both are 48 inches long and both occupy the same space except for the width of the ties. Both sections have zero radius. The radius and the length are the same. The same goes for equal radius curves of any size in any scale.
Take a 36 inch radius circle of HO and O gauge track. You can lay the HO circle on the top of the O gauge circle. Again, both occupy the same actual space except for width of the ties.
It is a different matter if you want to compare how many scale passenger cars that the two 48 sections will hold. Forty eight inches of straight O gauge track will hold two O scale passenger cars and the same 48 inches will hold about 4 HO scale passenger cars. In other words, a 48 inch section represents a longer prototype length in HO scale than it does in O scale. The same goes for curves. A curve of any radius in HO represents a gentler prototype curve than an O scale curve of the same radius.
My HO club has a minimum radius curve of 40 inches which is exactly the same curve as an O-80 curve. I would be thrilled if I had enough space on my home layout to use O-81 curves as a minimum on my O gauge layout. I could run anything that Lionel and MTH makes including Big Boys and scale O gauge passenger cars. In a like manner, I couldn't build a HO layout in the same space using a minimum radius curve of 40 inches either. Some of the HO Big Boys at the club have trouble getting around 40 inch radius curves because all drivers are flanged. NH Joe
