If you haven't already, you can read UDS studios own story about making Ignition. Going back to 1999 with archive.org I found the original website for the game. It seems they had some other tracks that didn't make it into the game. At least it lends some insight as to how they made it. Interesting pictures and track sketches too.
https://web.archive.org/web/19990429.../ignition.html
https://web.archive.org/web/19990423...ignbehind.html