Brendon Pywell, the man behind Bob's Track Builder, has created a new program called Race Track Builder. It looks like a massive improvement on BTB that I could never get used to using and is faster and you can now import Google Earth terrain and build a track directly onto it. Will definatly be giving this a try when it's released. He also released a video where he goes into detail of the new features and interface.
https://youtu.be/SbXY5w2hJF8
http://www.racetrackbuilder.com/