This question came up this week to create a redesign of a ditch in a Rock Cut area to facilitate the creation of more rock required for the project over a certain station range of the alignment.
The process started with the creation of two reference lines in two existing ditches of two adjacent roads being constructed. The user then wanted to compute a new ditch shape and a new Rock Cut surface to create more rock required for the project.
The design criteria was to use a -5% cut slope to tie into a Rock Surface. The source ditch line is below the target surface, so it is a cut slope, however they need water to drain away from the ditch base so they need a -5% cross slope to tie to the rock. From the Rock Tie they want to drop at 0.25:1 down to the elevation of the other ditch in the second road, and then connect to the other ditch line at 0% slope.
The redesign will therefore look like this
Video shows you how