Cross-sections set the points that make the road mesh. They allow rapid change in road widths, angles, randomness and determine the "snap to terrain" amount. They can be used to quickly create bumps, dips, gutters of any description.
Points can be grouped or moved indiviually in one cross-section or select multiple cross-sections in order to make changes to them all.
Lines above each point allow a quick way to move them vertically only.
Tracks are made from three main sections, the road, where the driving should occur, and two run-off areas to the left and right.
The various arrows around each selected cross-section allows quick modification of the sections or of the whole track. This allows faster modification as it avoid the tedious selecting of points before movement can occur.
The cross-sections of Tracks can be comprised of different amounts of points. Low detailed roads can be great for side roads and areas that are not intended for driving on.
RTB allows you to seamlessly join tracks with different amount of cross-section points (with the obvious limitation that at the join the individual points must align for each of the three sections).