... nose of a common crossing on the "A" timber. In the Scale 7 information sheet "Prototype Track Design and Construction" Figure 7 suggests that's it's 4" from the centre line of the timber. And that's the default Templot uses. But I can't see how this can be the case for either built up chairs or solid cast iron chairs. In the case of built up chairs, the crossing has a 3 inch extension in front of the blunt nose, which is bolted through the chair and the timber: 499_121146_390000000.png (Dimensions are for 7mm/ft with full size inches in square brackets) British Railways Track (ed 3), Figure 40 also shows a figure of 4", but this is from the center line of the chair, which is backed up by a footnote to Table 13 "The 'A' Chair comes under the nose of the crossing, the centre of the chair being 4" from the blunt nose". The main body of the built up chair is 8" wide, with an 3" extension ...