Creating a Line of Best Fit
Civil 3D can create lines and arcs of best fit based on selected points, entities, or by just clicking positions on-screen. This tutorial will walk you through creating a line of best fit, but it should be the same for arcs and parabolas as well.
Under the Home tab, in the Draw panel, select the Best Fit dropdown. Alternatively, you can enter the CREATELINEBYBESTFIT (or CREATEARCBYBESTFIT / CREATEPARABOLABYBESTFIT) command.
In the dropdown menu, select Create Best Fit Line.
In the Line by Best Fit popup window, select what type of object you’ll be using to define your line - e.g. From COGO points.
Select the points/entities you wish to best fit your line to and press ENTER.
A Regression Data panel will pop up. Press the green tick in the top right of this panel to confirm your line of best fit.