I have survey point data brought into ArcGIS using Survey Analyst Extension. I have created my 2D shapefiles of the cross-sections, thalwegs, and roadways but I can not get it to populate the zfield from the point data.
You need to create a ShapeZ shapefile.
can be done with GeoWizards Free Functions Point To Point Z (M) http://www.ian-ko.com/
When you load data in arcgis you assign the z value and the vertical crs
Edited: for comment - I have not used survey analyst.
However if you follow this process it might help you find the corresponding process for survey analyst.
I would think that SA would have a process for 3d point creation. that said...
In arccatalog if you right click on the folder you want to create a new shape file in> select new> shapefile.
The dialog should default to the point feature type. Select the check box at the bottom for z values. Then just give it a name and select edit for the spatial reference. Complete the xy coordinate system tab and then select the z coordinate system tab with the appropriate system OK to complete.