... mixed up. The flangeway gap dimension at the check rail is the instantaneous difference between the check gauge and the track gauge at that location. It's not necessarily the same as the V-crossing flangeway gap at the wing rail. And it's not necessarily the same for every V-crossing, i.e. if there is any gauge-widening. 3. If there is a problem with the track, it is impossible to see which rail is in error, using a combined multi-slot gauge tool to test it. 2_120535_080000000.png The rules are: a. Use a track gauge tool to set the running rails. This can be a roller gauge with two slots, or a triangular 3-point gauge to introduce automatic gauge-widening on sharp curves. b. Use a check gauge tool to set the check rails. (1. above) This is usually a two-slot roller gauge, with a flat-portion for gauging from the nose of the vee. This dimension is the most important in constructing track. You could just ...