Volume Calcs. from Sections

I was creating an as built Civil 3D model of a windfarm job and was asked to calculate a number of quantities. One was the volume of rock fill. This seemed straight forward - compare finished road surface against top of rock and you have your answer. The problem was that my finished road surface slopes down from road edge to top of rock and then batters back from there to meet existing ground. A straight comparison between the two would give incorrect volume, see below:

This includes the portion on the outermost batter. The volume we actually require is this:

To get this we need to create a new surface comprising the road edge featurelines and the featureline where the initial embankment intersects the top of rock. First lets look at my assembly… I am using a combination of generic subassembly (linkwidthandslope) and a conditional subassembly to model different conditions in cut/fill.

If you look at creating a surface from the featurelines generated by the corridor you see that all the individual linkwidthandslope subassemblies have a point code P2 and thus only one featureline I can choose (this would effectively give me the same result as choosing top links to create my surface).

You need to create unique point codes for each subassembly and thus unique featurelines to choose from for corridor surface.
Select the subassembly and change the Point Code  in Properties. Road edge here:

Then slope to rock:

Rebuild the corridor and in now corridor surfaces you should see some extra featurelines:

Now on cross sections you should be able to calculate the correct volume for rock fill by comparing this new surface with top of rock:

AUGI Library

Civil Intentions recently had an article in the May edition of AUGI magazine - on designing windfarm infrastructure using C3D. The contents of the article have been included in various posts on this blog over the last year but the complete article has been stored in the AUGI library at the following link -  http://www.augi.com/library/wind-farm-infrastructure

Pre-configure Survey Database Settings

I was training some users recently on the survey side of Civil 3D and was showing them how to create a survey database and edit the survey database settings. In the company there would be a number of teams surveying each day on a number of different jobs and a team of processors in the office on the CAD end. There would be multiple survey databases created by the processors each day. A question that arose was how they might ensure that each processor would enter the correct survey database settings, could you pre configure the database settings so that you didn't have to rely on the user entering them each time? I am unaware if you can do this from within Civil 3D but it is possible to do it through Windows explorer...

When you create a survey database in Civil 3D it is stored outside of the drawing and is effectively a folder in Windows that contains the settings and survey data. We can use this to create a 'default' survey database with the required settings and then before each new survey is imported, create a copy of this folder in Windows and rename it. It will then appear on the survey tab in Civil 3D.

First set your working folder in C3D - this is the location where your survey databases will be stored.

Hover you cursor over Survey Databases and you will see the path to the working folder.

Next create your 'default' survey database with the necessary settings. In my case I am going to create two 'default' databases...

...each with different coordinate systems and set to apply scale factor on import along with a number of other settings.

Now browse in Windows Explorer to the location of the working folder. You will see folders for each of the survey databases created in C3D. Before you import survey data in C3D you can create your survey database here by copying and editing the 'default' database to suit the job you are working on:

...and renamed to Cladd Reach in this case. You will need to close Civil 3D in order to be able to copy and edit the survey database folders.

Reopen Civil 3D and on the survey tab of toolspace now you will see the new database. To use it right click on it and open for edit.

Right click on the database and click on edit database settings to see that the default settings are already configured...

Creating a Profile from Single Line of Points

I have come across this situation a number of times, particularly when working with water schemes where you might have a single line of survey points for a number of kilometres along a road.

What is the quickest/easiest way to create a profile along the surveyed points? One way is to use the Create Profile from File command. You will need the point file in a particular format before we can use this command however. We need the point information in chainage and elevation rather than easting, northing and elevation from the surveyed points.

First join the points with a 3D polyline. The points are in numerical order so we can speed the process up by using a transparent command. Type 3DPOLY at the command line and when prompted to specify first point type 'PN for the point number transparent command. Then type the points you wish to join, 3-102 in my case and the points are joined instantly.

Next create a featureline from object and select the 3D polyline. Untick the option to delete the existing entities - we will use the polyline again to create an alignment along the points.

Select the featurline, choose Edit Elevations from the ribbon and then right click in the dialog box and select Copy All. (You will notice that we have the information we need in this dialog box as well as some extra we can delete in excel.)

Paste the chainage and elevation columns into excel and edit the file to suit the requirements for the profile from file command - see help menu. When you have only the information required, paste into Notepad.

Back in Civil 3D we need to create an alignemt for our profile. We will turn the 3D polyline into an alignment - first we must turn it into a 2D polyline. Turn on your drop down menus at the top of your screen (type MENUBAR at the command line and set the value to 1). On the grading menu select Polyline Utilities and then Convert 3D to 2D Polylines.

Next use the Create Alignment from Objects command to turn the 2D polyline into a Civil 3D alignment (we need this in order to create our profile). Now use the Create Profile from File command.

Select the alignment just created and the point file and click ok.

Select the alignment and choose Profile View from the ribbon to complete.

When creating the water network in plan it is useful to know where the high and low points on the road are for placing the air and scour valves. you can add labels to the horizontal alignment that indicate where these points on profile are. First you will need to create a best fit profile from the profile just created. (the best fit profile will have proper geometry - curves and straights - as opposed to just a series of straights joining the surveyed points).

Next select your horizontal alignment in plan, right click and select Edit Alignment Labels. Add in Profile Geometry Labels and select to label the high and low points as below:

This labels the profile high and low points in plan...

Using Civil 3D to Convert Drawing Coordinates

Thanks to Mark Green of Amicus Technology for the following post....

The example used here converts a drawing from Irish National grid (IG75) to the newer ITM grid.

Setting the coordinate system of the Irish Grid drawing

1. Open the drawing you wish to convert from IG75 grid to ITM grid

2. At the command prompt type ADESETCRDSYS and Enter

3. In the Assign Global Coordinate System dialog box click Select Coordinate System

4. In the Select Global Coordinate System dialog box select Eire-Ireland from the Category drop-down list

5. Under the Coordinate Systems in Category list, select Ireland1965.ING Irish National Grid referenced to Ireland 1965 (note that this is IG75 grid)

6. Click OK and OK again

7. Save and close the drawing

Setting the coordinate system for the ITM drawing

8. Start a new drawing using the Acadiso.dwt template

9. At the command prompt type ADESETCRDSYS and Enter

10. In the Assign Global Coordinate System dialog box click Select Coordinate System

11. In the Select Global Coordinate System dialog box select Eire-Ireland from the Category drop-down list

12. Under the Coordinate Systems in Category list, select ITM Irish Transverse Mercator 1995 with ETRS89 Datum:Ireland

13. Click OK and OK again

14. Save the drawing with a new name e.g. project123-ITM.dwg

Converting the IG75 drawing to ITM grid

15. At the command prompt type MAPWSPACE and Enter twice. This opens the Map TaskPane

16. In the Taskpane palette select the Map Explorer tab.

17. Under Current drawing, right-click on Drawings and select Attach

18. In the select Drawings to Attach dialog box, click in Look in to navigate to the folder with the

IG75 drawing

19. Select the drawing, click Add and click OK

20. Under Query library, right-click on Current Query and select Define

21. In the Define Query of Attached drawings dialog box, under Query Type, click on Location

22. In the Location Condition dialog box, under Boundary Type, select All and click OK

23. Under Query Mode ensure Draw is selected and click Execute Query

24. The drawing objects from the IG75 drawing should now appear but with ITM coordinates (check Grid Inquest program to verify)

25. Save the drawing.

Footnote: There is a common misconception that the Irish national grid system in common use is based on the 1965 adjustment. In fact this was only used for a short time and the readjusted 1975 network, referred to as IG75, is the basis for the pre ITM grid system. This misnaming appears in Autodesk MAP 3D and Civil 3D and MapInfo software among others. The difference between the 1965 and 1975 grids is up to approx 13 metres.

In MAP 3D and Civil 3D it is essential to select the coordinate system named

Ireland1965.ING as this is the correct 1975 grid while the coordinate systems named TM1965Irishgrid and TM1965Irishnationalgrid are the 1965 grid.

Grading Between Corridors

In the same project described in my last post there were two access roads that were close to each other but at very different levels. The embankments between the roads will grade from the back of the verge of one to the back of the verge of the other and vary in slope. See below:

This project is in its early stages and the design is bound to change. We need to 'tie' the two corridors together dynamically so that a change to either road will be reflected in the grading between them without having to manually make these changes each time.


The first step is to create the corridors for both roads. Then extract a dynamic featureline from one of the corridors for the relevant tie in point. In my case I am extracting the back of the verge for the higher road. See below:

Make sure to tick the 'Create Dynamic Link to the Corridor' box and then select the featureline you want from the corridor. This creates a featureline representing the back of the verge which we can now use as a target for our lower corridor earthworks.


Modify the lower corridor assembly to include a LinkwidthandSlope subassembly (find it on the generic tab of the toolpalettes - CTRL+3).

No in our lower corridor we can use this subassembly to target the extracted featureline from the higher corridor.

This creates dynamic grading between the two corridors.

If the design changes for either access road the grading between the two will update automatically.

Creating Profiles using Transparent Commands

I have been giving some customised Civil 3D training recently for site development works - mainly on creating access roads and grading for car parks on an extension to an existing factory.

The project data consisted of a topo survey from which we generated our existing ground surface. The  proposed access road layout drawing is in AutoCAD format with some proposed levels entered as plain AutoCAD text, see below:

The proposed access road centrelines were in polyline format which we could quickly turn in to C3D alignments using the 'Create Alignment from Object' command. We then created a profile along this alignment and sampled the existing ground.

We then needed to draw the proposed road profiles using the levels from plan. This is where the transparent commands came into play. Transparent commands are commands that you use while in another command to easily provide the first command with the information it needs. For example when we are drawing our profile we will be picking IP points on profile that will have chainage and elevation values. In our situation the level values are noted in plan alongside our alignment. We can use the 'Profile Station from Plan' transparent command to allow us to pick these points from plan and enter the elevation when we are drawing our profile. 


Start to draw the profile as normal using the profile creation tools. When prompted to pick your start point select the transparent command from the toolbar on the right of your screen as shown below:

The command prompts you to select a chainage from plan....

Then it allows the user to enter an elevation manually which we have in text format and is corrected here to provide a crossfall...

Continuing with this procedure along the entire road allows us to very quickly create our proposed profile.

There are many more useful transparent commands on this toolbar which I use regularly, definitely worth checking out.