QUOTE: Originally posted by JohnBarbieri My Hallmark AT&SF 4-8-4 and my Key SP GS-4 4-8-4 will operate perfectly satisfactorily on Kato 19" radius. I`d like to add an inner loop with Kato 15 " radius but don`t know if these locomotives will operate with a train behind them on this radius.Any and all advice would be appreciated! Thank you. -John in Memphis