ADD TRENCH IN CIVIL 3D SURFACES

[kalpeshpote]

how do i add trenches in an existing civil 3d surfaces 

[ianjchap]

Hi @kalpeshpote,

Quite a few options and things to understand on this question.

Firstly, when you say an 'Existing' surface do you mean that its Surveyed information? In which case, if your trench is new design, you'd want to keep it separate to the existing surface and model your trench as a new proposed surface. 

To model your trench, you can either use feature lines, matching the cross sectional width of the trench. Easiest way would be to offset from an upper edge for the next width and elevation. You can match existing elevation at the tie in/edge of trench by aquiring the elevations from that surface to your feature line.

Or, using a corridor and matching your cross sectional design with a sub assembly that works. Maybe using MultiLinks. Depending if you just need a surface or you're looking for Solids as an output.

If you're adding this to a surface already created then you should probably match the same way that surface has been built. By the look of your pic, as I cant see any corridor then I would go with Feature Lines. 

Feature Lines:-
https://help.autodesk.com/view/CIV3D/2025/ENU/?guid=GUID-89F4D3FC-5E3E-4047-9516-CCF6CE1A9345

Corridor Modelling:-
https://help.autodesk.com/view/CIV3D/2024/ENU/?guid=GUID-F2246A0B-809E-4801-97A5-EFACFA05EE46

Hope this helps, feel free to ask any other questions that aren't clear.

[Joe-Bouza]

If this is part of improvement, typically a FG surface would be created referencing EG.

Via corridor, grading, Feature lines, combination of all