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Work with IFC 4.3 Files

Use Civil tools with IFC 4.3 infrastructure models to run alignment-based review workflows in Autodesk Forma without relying on Civil 3D DWG files.

When an IFC 4.3 file contains IfcAlignment, Civil tools workflows are available after the model is processed and opened in the viewer.

Work with IFC 4.3 Files

  1. Export an IFC 4.3 model from an authoring tool before using it in the viewer.
    • You can use Civil 3D with the Autodesk IFC 4.3 Extension. The extension is available to download from your Autodesk Account.
    • You can also use any external tool that can generate IFC 4.3 files.
  2. Upload the IFC 4.3 file to the Files tool in the target project.
  3. Wait for model processing to complete.
  4. Open the IFC model in the viewer.
  5. Click Civil tools and continue with alignment-based workflows.

Considerations and known limitations

  • The IFC file must use IFC4X3 or IFC4X3_ADD2 schema.
  • The IFC file must include an IfcAlignment object with proper 3D alignment geometry (IfcGradientCurve).
  • Civil Tools for IFC 4.3 requires a new IFC conversion method enabled by default only for Forma projects created on or after July 22, 2025.
    • If your project was created before July 22, 2025, create a new project and upload the IFC files there.
  • Surface profile highlights that contain very small segments may display incorrectly.
  • Selecting an IfcGradientCurve from Model Browser can show a 3D representation that differs from the Civil tools highlight; the Civil tools highlight is the correct 3D geometry.

Frequently asked questions

Which IFC formats are supported?

Supported schema versions:

  • IFC4X3_ADD2
  • IFC4X3

Unsupported schema versions:

  • IFC2X1
  • IFC2X3
  • IFC4X2
  • Any schema version earlier than IFC4X3

I am using an IFC 4.3 file, but Civil tools are not available. Why?

The file may use the correct schema but still be missing the required 3D alignment definition. Verify the model contains an IfcGradientCurve with proper 3D representation included in IfcAlignment, then upload and/or export the file again.

I am using an IFC 4.3 file with IfcAlignment, but Civil tools are still not available. Why?

Possible causes include:

  • The IFC file was uploaded before required backend updates. Upload it again to ACC.
  • The project was created before July 22, 2025 and does not use the required IFC conversion method.

If the issue persists, contact support for further investigation.

Can I aggregate IFC files with other file types?

Yes. In Model Coordination, you can aggregate multiple file types. Civil tools workflows apply to IFC 4.3 and Civil 3D DWG files when visible alignment geometry is present.

Are there differences between Civil tools for Civil 3D DWG and IFC files?

No. The workflow functionality is the same.

Why can't I snap to alignment geometry in my IFC file?

Snapping is not available when IfcGradientCurve is missing from the model definition.

Parent page: Civil Tools

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