Export to CAD fails to create AutoCAD 3D polylines or lightweight polylines with an elevation

Description

The Export to CAD tool in ArcGIS 9.0 Service Pack 2 and prior versions, fails to create 3D polylines or the default lightweight polyline with elevation. The proper method of creating 3D polylines is to include the value of '3D Polyline' in the CADType field of the input feature class.
<a href='http://support.esri.com/en/knowledgebase/techarticles/detail/28335' target='_blank'>How To: Create AutoCAD 3D Polylines from 3D ArcGIS Line Features</a>By default, Export to CAD should create planer 2D lightweight polylines where the elevation of the polyline is set to the elevation of the first vertex of the input feature.In future releases, an [Elevation] CAD field type may be included that would simplify this process using the Export To CAD tool. The elevation field could be used to set the elevation of exported CAD entities.

Cause

Export to CAD fails to properly handle the request to create 3D polylines in AutoCAD.

Workaround

• Use the [Create CAD XData] tool to add an XData value and include the elevation value in the table. In AutoCAD, select all the desired line entities and read the XData and update the entity to get them to the right elevation.
• Although shapefiles do not support circular curves or splines, if there is access to AutoDesk Map, copy the data to a shape file and use AutoDesk Map to import the data.