Once again I was looking for a more clever way to solve my layout planning problems (previous thread http://www.jnsforum.com/community/topic/9010-layout-planning-geometric-calculations-for-asymmetric-layouts/), and I came across the Hallade Method. This isn't the whole solution to my problem exactly, but it's some interesting background on how this was (is?) handled in 1:1 scale. It may also provide more information about the white posts that Charles asked about in this thread http://www.jnsforum.com/community/topic/10440-short-white-posts-between-yard-tracks/
https://en.wikipedia.org/wiki/Hallade_method