... the rails and flangeway gaps, and the size of the timbers (ties). In the former case you might produce something like this: gn15_9ft_65.png Is that something like what you are asking for? In the UK and Templot, G-scale is called "No. 3 Gauge" and you can find it in Templot in the standard list: 2.5" track gauge, 13.5mm/ft (1 :22.58) scale. It's exactly half of the model engineer's No. 5 Gauge (5 inch track gauge): gauge3.png After which you can change the track gauge, timber (tie) sizes etc., to whatever the Gn15 variant needs. The shortest standard switch in Templot is the GWR 9ft curved, as you found. Even with that the very narrow gauge means that the V-crossing (frog) falls within the switch itself, and some closure timbering needs to be omitted. Ideally you need to create a custom switch* to fit. If you let me know some information about Gn15, such as typical rail width, ...