It's been quite a while since I've posted an update. I took a step back when I realized bridges and tunnels plus road crossings at grade were making things very complicated and causing lots of one-off code. I realized that I needed to change the tile data model to allow for road/track information at multiple heights within the same tile. That led to a rebuild of the track building tool to also support multiple height levels of track on the same tile. More work to go but here is the start of multi-height tracks.