Interestingly, when the Rockford O Scalers first formed back in 1973 with the intent to build a modular layout to set up at train shows, all of us were previously in HO Scale.
Not knowing any better, one of our members suggested we simply double the popular HO radius of 30” and 32” for our curved module sections and that’s what we did. However, it didn’t take long to realize that these 60” and 64” curves were not suitable for running mainline passenger trains with 85’ scale cars and large steam locomotives which is what we wanted to do. We could get the passenger cars to run around these curves but they looked toy like doing so but some of the locomotives simply would not negotiate them at all. Consequently, we rebuilt the curve modules using our current 88” and 92” radius.
Obviously, the choice of curvature is predicated on how much space is available and the type of equipment one wishes to run. Simon’s suggestion of 72” radius is probably a good compromise if space for larger radius curves is not possible.
