Various depths of topsoil removal

[MattCichon]

Hi,

just like in the topic. Often is so that the topsoil thickness changes along the road. Is there an option to change it in ranges relative to eg surface. Or do I have to do it like this:

1. Paste the eg in a new surface

2. Lower it on a depth that I want

3. Make different sample lines for different topsoil removal areas

4. Add various surfaces to proper sample lines.

Thank you,

Matt

[Mike.M.Carlson]

Hello,

I don't see a problem with your approach, but it could be a little labor-intensive.  I recently used a simple custom subassembly (Created in Subassembly Composer) that would attach to the existing edge of travel way and target a ROW offset.  Then the subassembly samples the EG surface and offsets down based on a user-defined input parameter set up to represent topsoil excavation depth.  A corridor surface was then built to represent post-topsoil removal.  For different topsoil removal depths, I broke up my corridor into different regions for 6", 8", 12" 18", and 24" removals. 

You could also set it up to find the average depth relative to the EG or create a smooth grade from the ETW to the ROW that is no shallower than the topsoil removal thickness you specify.

I hope this helps.

[cwr-pae]

You seem to have some data on the thickness/depththe top soil. Can you convert those 'depths' to cogo points and create a surface that can be targeted by a subassemblies in a corridor?

[MattCichon]

Hallo Mike,

thanks for response. Can You share this assembly? I'm a C3d beginner, I most use the standard subassemblies. In SAC I can do just simple assemeblies...

Greetings,

Matt

[MattCichon]

Hi cwr,

yes this is a way. My EG surface consist of COGO points. I can then divide them into ranges. put them into different  surfaces and then lower this surfaces. But I find this method very artificially...Is this what You meant?

Greetings,

Matt

[cwr-pae]

How do you know the depths/thickness of the topsoil in the different areas? Is it surveyed points with an elevation or elevation difference?

[Mike.M.Carlson]

Hello,

Here is the .pkt file for that custom subassembly I mentioned.  Simply rename the extension from .zip to .pkt.  To import the .pkt file, you will have to import it to a Tool Palette as described at ~2m30s in the video below:

https://www.youtube.com/watch?v=Ya903B0R_v0   

You will need an edge of travel way (ETW) or edge of pavement (EOP) or shoulder as a corridor baseline.  Set the subassembly top soil removal depth in the subassembly properties (You may need several versions of this first assembly specifying different topsoil removal depths).  Then you simply build a simple corridor and target an offset (i.e., ROW alignment or pline or feature line) and set the EG surface.  Then you would break the corridor up into regions based on the different top soil removal depths and set the appropriate assembly with the proper subassembly with the topsoil removal depth specified.

I hope this helps.   

[MattCichon]

Thank You very much Mike,

I'm going to test this assembly and give a feedback. Thank You for a very precise description of how it works too.

I hope it's in 2018 format because yesterday i had some issues with a *.pkt from 2020.

Have a nice day,

Matt

[MattCichon]

Hi Mike,

could You please upload the file once more? Because it doesn't open in SAC or in C3D. An error occurs - "an *.atc file is missing"...

Thank You,

Matt

[Mike.M.Carlson]

Hi Matt,

You downloaded the .zip and renamed it from .zip to .pkt?  

[neilyj666]

I use a dynamic differential TIN to create a base of topsoil surface and use this as a target.

[Mike.M.Carlson]

Good point @neilyj666 .  @MattCichon  here is an AU handout that describes the process @neilyj666  mentioned. 

I'm torn which way would work best for your case though.     

[Mike.M.Carlson]

Here is the same custom subassembly, but I saved in SAC v18.

[Anonymous]

I always use the differential tin method as it's easy to incorporate changes or new information. For topsoil depths, if no ags file is available to model the GI properly, I usually just create points with elevations at the relevant depths, create a TIN surface from these, then a volume TIN between that and my existing ground, then paste the volume surface into another TIN for further use. If the points available for the depths do not cover the area required then I will usually copy the points locally to ensure the peat depth surface fully covers the area required for analysis.

Regards,

Peter

[MattCichon]

Hi Mike,

I still get this error. I did just like you said - changed the format of the zip to *.pkt

I wanted to open it first in SAC, mine is 2018... In C3D I get similar error.

Thanks for the *.pdf file. I've never heard of this dynamic TIN surface. I'm gonna read it and try to understand. Thank You GUYS for so much interest in this topic.

Greetings from Poland,

Matt

[neilyj666]

@MattCichon post back if you have any queries with the dynamic TIN - I use a variant of this method when supplied with a proposed ground model and I need to derive the earthworks outline.

@Anonymous - this is the method I use and if the ags file is supplied it's very easy to use the method although some manual adjustments may be required if for example a existing road runs through the middle of the project

[MattCichon]

Thank You Neil,

I'm sure I'm gonna post back:) One more question - what is a "ags" file? Is it a point cloud from e.g. Lidar? What kind of information do you get in projects in the US? Only *.pdf files or maybe *.dwg? How do you model the existing ground? Do you have to do it manually by clicking every point on the map and give it a height? I know it's off the topic, but I'm just curious.

Regards,

Matt

[neilyj666]

@MattCichon  an ags file is the electronic version of the ground investigation report and can be used with the Geotechnical module to display borehole data and extract surfaces. (I use Holebase which is essentially the paid for version of the Geotech module).

I'm not in the US but we always ask for (and mostly get) dwg files but typically dumbed down vanilla CAD versions rather than native Civil versions. LandXML files area useful if we can'f get dwg although we also get pdf files but these are next to useless without a lot of work (PDFIMPORT has helped with this).

If you only have a pdf of the orginal survey then you'd have to use pdfimport and scale the resulting block and then click each point and assign a level and code. You also need to create breaklines (use Line command and snap to points then use Join) to ensure the contours are formed correctly. This can be extremely tedious so it's always worth pushing to get an electronic version of the DTM (even the triangles are better than nothing as these can be used to create a civil surface)

[MattCichon]

Hi Neil,

thank You for an answer. I've read the *.pdf file about the DDTS and... I don't get it... But I've seen there's a video tutorial on the Autodesk site - I'm gonna watch it in the evening. Hope this helps. Otherwise I'm gonna ask You Guys:)

Greetings,

Matt

[neilyj666]

The DDTS method is a little mind bending initially but is so obvious one you understand it so I'd suggest you have a practice with the concept....:) It is basically comparing a surface of topsoil (or whatever) DEPTHS to the existing ground surface LEVELS.

1. Create a new drawing and shortcut in your EGL
   
   
2. Create a simple 2d rectangle polyline and give it a level of 0.3 ensuring it goes beyond the extent of the EGL, draw another polyline somewhere in the middle and give this a level of 0.6 (the topsoil depth must be +ve rather than -ve as you'd expect - if the depths are -ve you can create landforms above the EGL but i digress)
   
   
3.  Make a surface from these two poly lines (TS DEPTH) which assumes there is a general thickening of the topsoil towards the centre of the site i.e. from 0.3 at the edge to 0.6 in the middle
   
   
4. Create a Volume Surface (VS Inferred Base) using the TS DEPTH as base and EGL as compare
5. Paste this volume surface into a new regular surface (INFERRED TS BASE) and it is available for normal use.
   
   
6. compare levels using the tooltips and you will find that the difference between the INFERRED TS BASE and EGL surfaces correlates with the depths shown on the TS DEPTH model e.g. at the boundary of your EGL it will be slightly larger than 0.3 (depends on how far the TS DEPTH model extends beyond the EGL extent)
   
   
7. You can add another polyline - (or any number of points) with any depths you want to prove the concept - to TS DEPTH and refresh the surfaces and the comparison in 6 will still hold true. 

I could do a screencast if you are still unsure of the procedure - let me know