Occasionally when creating grading objects in Civil 3D you may choose to apply the grading to the entire length of an enclosed feature line. If you want to go back and edit the grading object ends there isn’t an obvious way to break the grading without deleting it and starting over. A less obvious way to be able to edit the start and end of a feature line is to use a transition.
Go ahead and use the Create a Grading Transition Tool and select a point within the grading object. Set a starting point for the transition and then give it a slope. Now go back and delete the transition. You will then be able to edit the start and end points of the grading object. Here’s a short screencast: http://screencast.com/t/lSAqEFToov6
Watch out when you adjust the end of the grading object, if you past the start point of the feature line you won’t be able to grip edit the other end of the grading. You’ll notice the behavior at the end of the screencast.
“Wish I may, Wish I might, Get the wishes I’m wishing tonight… Twinkling little star, please let Autodesk find the knowledge to fix grading objects and their crazy unstable behavior…please.”
I agree that my grading objects also display crazy unstable behavior. Working start to finish with no modifactions is fine. But as soon as I start editing my design – the point of the Grading tools to begin with – the unstable behavior begins and progressively gets worse.