The videos below are an exercise that covers the process of creating a parabolic pavement that fits to two surveyed strings. The background on this is as follows
The paving contractor that raised the question stated that when they get to site to do their work that the curb is already in place, and unless the curb is horrific and needs to get ripped out, that they have to fit the pavement to the curb that is there. So they go out with GPS or Total Station to measure the curb lines along the lines that they have to tie in to. They measure every 2m along the edge of pavement lines.
From the measured data they then want to compute a parabolic pavement shape defined by the typical section, where at the half way points between the centerline and edge of pavement they have e.g. 2/3 of the elevation delta between the edge of pavement and the centerline. They wanted to come up with a way to use TBC to compute this accurately and quickly from the measured lines. In the example we use the Best Fit Linestring to compute the best fit curvilinear lines along the surveyed strings, however if I was to do this today, I would likely use the Linestring Optimizer instead as that has better controls for doing that part of the process.
The calculation of the quarter points is a trick, the corridor template once created can be saved and then reused using Copy and Paste of the template into any project where you need to do the computations.
Example Data if you want to follow along and try this yourself
Alignment.vcl (143.0 KB)
Parabolic Computation Template (8.5m x 3 Percent).xml (3.0 KB)
Parabolic Pavement - End Point.vce (199.0 KB)
Parabolic Pavement - Start Point.vce (113.2 KB)
Two Surveyed Strings.vcl (378.1 KB)