It’s the Little Things – 2

As we considered last week, it is the little things that sometimes can make our day and before long we wondered how we lived without some of these little tweaks. This week we are going to look at another little addition to Civil3D.

Pipe Networks and Hydraulics are still separate. However, in 2010 there are coordinated much better. For example, you can import/export to STM files. There have been additional properties added to structures and pipes. Let’s look at structure properties. Do you see what I see?


What about pipe properties?


There is now a whole section for setting certain hydraulic properties for a structure or pipe. Of course, we could set the manning’s for our pipes for awhile. What good does that really do?

In your Pipe Style>Display>Profile are two new components that you can display. EGL and HGL! When you draw your network in profile view, the HGL’s and EGL’s (which can be entered manually or come over from the imported STM file) will be drawn also.


  1. Fair warning: the EGL and HGL lines are drawn from End Elevation and Start Elevation. In the event that you have a backwater condition on the start, both your HGL and EGL will be incorrect. The Q value of the pipe is the calculated flow from the STM. The Expression is Capacity of the pipe flowing full.

    In my view, this is an unfinished work because of the limitations of the Hydraflow tools inability to provide, or store the correct HGL, and EGL slope. It calculates those values iteratively when drawing the HGL/EGL within the program, but it does not appear to store the data. Hydaulic Jumps will be incorrect, rather they will be missing.

    Using expressions to complete the analysis is going to be difficult without storing additional information on the pipes. Apply Engineering Judgement!

    I don’t know of any other way to say this here: Its a work in progress and we need more expressions to properly establish the EGL and HGL information correctly.

    I have no plans in Civil 3d 2010 to turning on either EGL or HGL in the dwg file.

  2. “work in progress”… is that like Grading Objects then?

  3. No, not like grading objects. There is no calculations within Civil 3d to establish the EGL or HGL, it is just a place for the information provided by Hydraflow. Showing the HGL incorrecty will likely not crash your computer, it will just get you fired!

  4. Kevin Spear says:

    you guys are 2 funny…

  5. Kevin Spear says:

    I wish we had structure properties for area tc and cn just so the data exchange doesnt require re-entry. Wait – now i either sound like NASA or bad hefner pun… I choose NASA, yeah…