imageI have been wanting to spend time researching ways to integrate the use of Civil 3D and Inventor, but felt that I had little time.  Edward Winter (Twitter: @iPinda) asked me to look into this a bit.  I am really glad that he did.

What we needed was to get a Civil 3D Alignment into Inventor, then design something through the Alignment, and then return the end result back into Civil 3D where it belongs.  So that’s what I did. 

The process that was in place involved Mechanical Desktop with a few conversions.  I wanted that cleaned up substantially.

For the next few articles I will detail what I did, what worked and what did not. This is not a tutorial, but a discussion of what works and how. I move through the material quickly, so you need to have a basic understanding of Civil 3D and Inventor. Let’s get started.

The Civil 3D Alignment

The Civil 3D Alignment will not be read in Inventor as an ‘Alignment’. In Civil 3D, the Alignment is a reactive component that is alive, but to the remainder of the design community it is a 2D polyline, tic lines and text.  Inventor will read in the tic lines and text, but not the Centerline alignment, since what you see is a mathematical representation of the alignment in a database.

What about vertical data.  3D information is stored in a profile, separate from the alignment.  Are you frustrated yet. Good, then you are right in line with everyone else.


There are solutions to the problem.  We can configure a block to gather whatever we want, we just need to treat it a bit special.  The following procedures are detailed in terms of what you want access to in Inventor. You can then use as many or few as you like.

  • The Alignment Stationing and Tics
  • The 2D Alignment – Mathematically correct
  • The 3D Alignment including Vertical Profile Information

General performance

We can Wblock out what we want, but the best performance with the import can be achieved by saving the DWG file as a temp file. Create all entities as needed in the following paragraphs. Once completed, erase everything unwanted including profiles, etc, purge the drawing and Save. 

Optionally you can feed the entire project drawing to Inventor and manually select the layers desired, but I am more comfortable sending a smaller file to Inventor.

Alignment Stationing and Tics

The stationing for an AutoCAD Civil 3D Alignment can be read automatically without any additional preparation.

No Wblock ! Just SaveAs and proceed on.

Acad Layer Name = Inv Sketch name.

The 2D Alignment – Mathematically correct

  • Copy the Alignment to the side
  • Explode it ONCE
  • Reposition back on top of it’s original position.

I recommend a recognizable new layer for the resulting block like ‘Align-2D’ in case you want to filter your selection as you import into Inventor. 

Inv Sketch Name Auto indexes ‘Sketch1’, ‘Sketch2’, etc.

The 3D Alignment including Vertical Profile Information

  • Use the Civil 3D tool ‘Create Feature Line from Alignment’.

Ribbon->Home Tab->Create Design panel->Feature Line Pulldown->Create Feature Line from Alignment


This dream of a tool will gather the vertical profile data into the alignment geometry, and create a Feature Line in 3D space. 

  • Now explode it ONCE. 
  • Move from 0 to starting station elevation (only if spatial relationship is needed)

Remember the resulting Polyline will start at 0 elevation in order to represent changes in a relative manner.  If you need the component’s origin spatially correct, then move the resulting 3D Polyline up to the correct elevation.

Make the layer recognizable for filtering during the Inventor Import procedure, such as ‘Align-3D’. This will come in properly, but remember that we need to use the 3D Import setting.

Acad Layer Name = Inv Sketch name.


I brought in all the components. Why? I want the stationing so I can get reference things according to the stations. The 2D alignment is great for swinging geometry through the curves. The 3D for my vertical orientation.



Use the Import command from the Insert panel of the Manage Tab in the Ribbon. If you will reference 2D and 3D data, then you will need to make 2 passes at this. Each pass will create a new Part file.  We will collect the 2D information in one file, and the 3D in another.

Ribbon->Manage Tab->Insert Panel->Import

Select the DWG file containing the Alignment components we prepared. Proceed through all the prompts associate with an import, generally the defaults are good. Along the way you may use the layer filter to select specific components by layer. The next thing that is absolutely critical is the 2D/3D setting.


When inserting the 2D components, use the Project wires to 2D sketch setting.  For the 3D components, use the Wires to 3D sketch method. Each pass we make at this will create a new part file. This is OK.

We have 2 halves. Let’s combine them using the Derive Component tool.

Activate the 2D part file, and save it as the final file you desire.  If the 3D polyline was imported as a 2D sketch along with the 2D, simply erase the sketch named for the 3D Polyline. Then Derive a component from the 3D file that was just created by the import.  Select the 3D sketch from there. Now you have it all packaged together.  You can save that imported 3D file (the one we just derived from) as something for safekeeping (recommended), or just break the link with the original file.


That’s it.  Now you have 3 sketches.


In the image above, you should see Sketch ‘0’ which contains the text and tics from the Alignment ‘0’ Layer, Sketch ‘export’ that I renamed from ‘Sketch1’ which contains the 2D Polyline data, and the component ‘ali-fl4.ipt’ from the 3D derived component.


Corridors were being used to extract information in 3D space.  This is perfect if a corridor is in place driving the origin of the Inventor components.  If not, the Creating a feature line from an alignment and profile is definitely the bomb.

This may seem like a great deal of preparation, but once you do it a couple times you’ll find if quite fast and easy. The next article will discus using the information in Inventor to create some basic components along the alignment as required, perfectly related in space.  More will follow through Fusion and into Civil 3D to tie everything up back up. Later I will discus file and transfer insight, and some alternative procedures as well. Keep checking back.

If any of this is confusing for you and you want more info, please don’t hesitate to ask.