How to Export Contour Shapefile to AutoCAD with Elevation and Layer Information

ArcMap 10.8.2 → AutoCAD / Civil 3D

When working with topographic maps, contour lines are often available as a GIS Shapefile. But when exporting them to AutoCAD, we usually need more than just 2D geometry.

In this workflow, I converted a contour Shapefile from ArcMap 10.8.2 into a DWG containing:

• Correct AutoCAD layer names
• Different layer colors
• Correct contour elevations
• 3D Polylines
• Usable geometry in AutoCAD/Civil 3D

1. Understand the Source Fields

The original contour Shapefile contained two important fields:

• FCODE – identifies the contour type
• COV – contains the contour elevation

FCODE	Contour Type	CAD Layer	Color
20111	Index	T-CON-INDEX	34
20121	Intermediate	T-CON-INTERMEDIATE	251
20131	Supplementary	T-CON-SUPPLEMENTARY	2

2. Add CAD Fields in ArcMap

In ArcMap 10.8.2, go to:

ArcToolbox → Conversion Tools → To CAD → Add CAD Fields

Select the contour Shapefile and run the tool.

This adds the CAD fields required for the Export To CAD workflow, including fields such as:

CadType
Layer
Elevation
LyrColor
LyrOn
LyrFrzn
LyrLock
LyrVPFrzn
LvlPlot

3. Set the Contours as 3D Polylines

Open Field Calculator for the CadType field. Select Python → String and enter:

"3D Polyline"

This tells ArcMap to export the contour features as 3D Polylines.

4. Transfer Contour Elevation

The contour elevation is stored in the COV field. Calculate the CAD Elevation field using:

!COV!

For example:

COV	Elevation
3200	3200
4600	4600
5600	5600

This transfers the GIS contour elevation to the CAD elevation field.

5. Create AutoCAD Layer Names

The Layer field is used to assign the exported features to AutoCAD layers.

Use Field Calculator with the following Python expression:

"T-CON-INDEX" if !FCODE! == 20111 else "T-CON-INTERMEDIATE" if !FCODE! == 20121 else "T-CON-SUPPLEMENTARY" if !FCODE! == 20131 else ""

The result is:

FCODE	AutoCAD Layer
20111	T-CON-INDEX
20121	T-CON-INTERMEDIATE
20131	T-CON-SUPPLEMENTARY

For this project, FCODE values outside these three codes are left blank.

6. Set AutoCAD Layer Colors

I used the following AutoCAD ACI color values:

Layer	ACI Color
T-CON-INDEX	34
T-CON-INTERMEDIATE	251
T-CON-SUPPLEMENTARY	2

Calculate the LyrColor field using:

34 if !FCODE! == 20111 else 251 if !FCODE! == 20121 else 2 if !FCODE! == 20131 else 0

7. Configure Layer State

For this workflow, I used the following CAD layer settings:

Field	Value
LyrOn	1
LyrFrzn	1
LyrVPFrzn	0
LyrLock	0
LvlPlot	1

The lineweight and linetype fields were left at their default values. The LyrName field was also left blank.

8. Export to DWG

Once the CAD fields are prepared, go to:

ArcToolbox → Conversion Tools → To CAD → Export To CAD

Select the contour layer as the input feature and choose:

DWG_R2018

Run the export and open the resulting DWG in AutoCAD or Civil 3D.

9. Verify the Result in AutoCAD

Select one of the exported contour lines and open the Properties palette.

The object should be a:

3D Polyline

The layer should correspond to its FCODE, and the Z elevation should correspond to the original COV value.

For example, one exported contour showed:

Object Type: 3D Polyline
Layer: T-CON-INDEX
Vertex Z: 3200.0000

This confirmed that the GIS contour elevation had successfully become the Z elevation of the AutoCAD 3D Polyline.

Final Workflow

Contour Shapefile
       ↓
ArcMap 10.8.2
       ↓
Add CAD Fields
       ↓
FCODE → Layer
COV → Elevation
CadType → 3D Polyline
FCODE → LyrColor
       ↓
Export To CAD
       ↓
DWG_R2018
       ↓
AutoCAD / Civil 3D
       ↓
3D Contours with Layers and Elevations

Quick Reference

FCODE	CAD Layer	Color	CAD Type	Elevation
20111	T-CON-INDEX	34	3D Polyline	COV
20121	T-CON-INTERMEDIATE	251	3D Polyline	COV
20131	T-CON-SUPPLEMENTARY	2	3D Polyline	COV

Conclusion

Using Add CAD Fields + Field Calculator + Export To CAD, we can convert a topographic contour Shapefile into a structured DWG without losing important contour information.

The key relationship is:

• FCODE → AutoCAD Layer
• COV → Elevation
• CadType → 3D Polyline
• FCODE → Layer Color

The final result is a clean 3D contour DWG ready for AutoCAD/Civil 3D, with meaningful layers, layer colors and correct contour elevations.

This workflow can be especially useful for topographic mapping, survey work, road design, hydropower projects, Civil 3D surface creation, and engineering drafting.