Level Differences (Execution project Z values minus observed Z values)

[Ribeiro]

My name is Ribeiro and I work for the Portuguese Government developing inspection work in roadway building area.
Before each pavement laying I usually perform a survey in order to verify the Z-levels used by the constructor.
My question is:
- Can I use 3D points randomly observed in the sub-pavement to establish differences in level (height) to the correspondent corridor COGO points (Civil 3D project points)?. Putting it in another way (at least trying to): I observe one point at a determined chainage and offset obtaining it's 3D coordinates. With the 2D values (X,Y) can I obtain the correspondent 'project' value and establish a difference to the observed one (supposing of course that I have my corridor builded...). What about if I have 100 observed points?

Thankfully,
P Ribeiro

PS - Please let me know if I can post the same question in the Portuguese forum (maybe it is not a Civil 3D forum)

[MHultgren]

Use your observed points as a seperate point group and you can import them into your corridor to find the elevation or depth from surface easily enough.

[hingles]

Take your design surface and use the observed points to build a surface from the survey observations. To compare them to each other;create a sample line group and plot the differences in section views.