06-21-2010, 09:25 AM
22" radius, so the interior diameter will be about 40", not 20". That access issue only comes into play with N scale helixes.
Fan of late and early Conrail... also 40s-50s PRR, 70s ATSF, BN and SP, 70s-80s eastern CN, pre-merger-era UP, heavy electric operations in general, dieselized narrow gauge, era 3/4 DB and DR, EFVM and Brazilian railroads in general... too many to list!