I don't really understand the purple lines, which segments are alternatives to which other segments.
If you want your own line from Spawntown to Darvincia, that can be planned. Such a line would be more free in where to go than redirecting the red line, but a general southwest direction without too many slowing bends would be desireable so that it's useful for future developments in the southwest direction.
The thick purple is an additional line that could be a segment of a ring line, according to the web plan. If you prefer this plan, I can approve that (thick lines) alternatively to the above plan.