... line is straight through, where-as the other diverges around the platform. double-edit: use tinyurl for the link to Swinton posted: 24 Jan 2009 13:57 from: Martin Wynne richard_t wrote I'd like the divergence, if that's the right term over 3500mm if that's possible (Scale7 now). It's an increasing separation on a double-track Hi Richard, Now that you've given me all the information (no-one ever does this first time), I can have a go at helping you: slewed_transition.png To minimize disruption to the ruling curves, ideally both tracks should be adjusted. But for this exercise I left the outer curve fixed and modified only the inner one. It's necessary to combine a transition curve and a slew together. The transition curve changes the radius as required, and the slew then shifts the radial centres into alignment. A certain amount of trial and error is needed for a perfect result. Starting from the inner platform curve, I first transitioned out to the radius of the inner double-track ( ...