Intelisolve and Civil 3D Round Trip Tip

By Matthew Anderson, PE

Ever wonder why the inlet you added in Hydraflow Storm Sewers (HSS) shows up as a Headwall in Civil 3d? Why isn’t my LandXML import as I expected? Mark Scacco’s AU presentation and LandXML hack is a godsend. I at least now can round trip my data and not deal with a plethora of Networks.

But, I have always found LandXML import behavior odd. I had to dig deeper. To find out more, join me after the jump…

The Civil 3d object model is based on structures and pipes. HSS sizes pipes and inlets. LandXML is the language in between.

Isn’t an inlet just the frame? Where does that leave me? Let’s take a look at HSS. (This is version 2005)

The HSS program model contains the following structures.


All of the Inlet/Junctions are of some sort of Inlet Structure, beyond the Outlet and Inlet 1. I have attempted to find anything that might indicate Structure Size in 2005. I can’t find it.


Okay, how does that affect Civil 3d? A little XML Notepad exploration is needed.


After exporting the LandXML from HSS, the structure diameter and lossCoeff is missing from the LandXML output. Are they supposed to be? Let’s import it into Civil 3d anyway.

Civil 3d imports the HSS design as follows where the Name field is the HSS Inlet/Junction Type and the Description is the Civil 3d Part Description that Civil3d selected. Please note, I did get a number of Multiple Part Families warnings from Dana’s child, Panorama.


Civil 3d matches the un-sized inlets structures to the first non-round or rectangular Part in the part lists. In this case, it’s a headwall.

It appears to be a limitation of the LandXML schema. Hopefully, Civil 3d will allow a LandXML Structure Mapping template. Good news, Start with Civil 3d. With Mark’s little hack, your inlets will not become Headwalls.

Please note that this works with both 2003 and 2005 versions of Hydraflow Storm Sewers. (I haven’t had the heart yet to uninstall 2003)


  1. Thanks Matt for the informative post.

    As you may know, we sometimes have “guest” bloggers. Matt Anderson has been a long time member of the community and a frequent commentor to our posts. This is his first post as a guest blogger and it seems to hit the target with relevancy in both timeliness and content.

    What do you think? Please either comment here or drop me an email at mark.scacco at and let me know what you think of Matt’s post and if you’d like to hear more from him.



  2. It’s always good to hear from Matt.

  3. Great info Matt. For those of us who use HSS, we can only look forward to the day where hacks aren’t needed to do the roundtripping. Keep on posting.

  4. Autodesk’s Stormwater discussion group is up and running at

  5. Marcos Silva says:

    Well, i guess this is somewhat related to my problem.

    First, let me explain i’m a new user to Hydraflow Storm Sewer. I have been reaching relative sucess, but some problems are preventing the desired ‘Mission Acomplished’.

    The main problems are: i can’t import back to C3D the correct pipe size. All pipes comes with 250mm, i read a related topic about ‘missing diameter’ in structure XML, or something like that here. But i could not solve my problem yet.

    My second problem is regional. I would like to customize the diameter options into Hydraflow, so i can do my projects according to products offered, not with predesigned for American Units diameter.

    Anyway, if anyone could also suggest some discussion forum for Hydraflow related topics, i would be very pleased. The Autodesk – Discussion Group is one my first sites for doubts, but it’s kind slow. And this topic from the Matthew Anderson really put light into some problems.

    Thank you.

  6. Marcos –

    At this point, Hydraflow was design for only American Units. The SI units are the soft conversion of the American Unit. While I look forward to what the future might hold from Autodesk, there really isn’t anything available to my knowledge to fix that. The return trip from Hydraflow into Civil 3d should work – I would suggest looking at both the units for diameter in the LandXML and the Civil3d Import routine.
    If you need any assistance, feel free to drop me a line.

    Matthew Anderson, PE
    anderson at jaseng dot com