@Midnight Express posted:
Next layout will be 0-54 MIN !
Personally, I'd recommend a minimum of O72, at least on any mainlines. If you do O72, 3.5" clearance from the track centerline, and at least 5.5" separation of concentric curves, you'll eliminate most of the contention issues. This will also allow you run virtually any O-scale locomotive or car, scale or semi-scale. The only remaining parameter is the clearance height, so far 5.5" above the railhead seems to be sufficient for all the cars and locomotives I've tried.