... . Jim. posted: 5 Nov 2015 15:25 from: Martin Wynne Hi Jim, The straight switches in Templot are based on Table 7 in BRT3 (1964). In the 12ft switch, the virtual switch heel (where the offset is 4.5") is 30" short of the switch rail joint. So the offset at the joint is about 1" wider at 1:32 deflection angle (strictly speaking the section between the heel and the rail joint is curved at the turnout radius). See: 2_051019_260000000.png The 4.5" offset, minus 2.75" rail width, would leave the standard 1.75" flangeway clearance between the rails. But because the switch rail is opening 30" further back, the actual open clearance is greater. The usual requirement is 2" clear all along behind an open switch blade, to prevent wheel backs hitting it, which could damage stretcher bars and detection gear. But if you are modelling the Caledonian, it is quite unlikely that this switch is the correct prototype for you. Ideally you should be ...