As a side note . I have a 15" HO radius inside an 18" radius loop ( 12 sections each ) Bachmann does not offer a 15" connector rerailer . I used an Atlas 842 HO rail joiner .Don't even think of using long cars .On the 15" radius loop I only use a Bachmann trolley . Talk about small .The two loops I just described are on a 38" X 38" platform . Have fun !