What diameter track do I need to run parallel to a quarter circle of O72 track.
My lionel big boy has 2" overhang and a long propane tank car has 1 3/8" on a tubular O72 curve. So the tracks must be separated by at least 3 3/8", say 3 6/8"(propane less for larger radius). Should I use a O84, O96 or 108 curve to have tracks parallel?
Second, where can I acquire a half circle of tubular track in this diameter??
Third, assuming I cannot find this, how long a straight should I put between each section of O72 track to approximate this diameter?
thanks for help
stan