The process of importing contours from shapefiles is actually a two step process, since the results from Autodesk’s MAPIMPORT command does not elevate the resulting polylines. This is a step-by-step procedure on how to take a shapefile of contours to elevated polylines in AutoCAD (Map/Civil3D).
ESRI Shapefiles are not just the SHP file. While some importers can import the geometry from just that one file, a lot remains missing. That’s why it’s important to send the package, not just a single SHP file.