Grading Hell(p)

[Anonymous]

Hi everyone,

I've been using Civil 3D for about 4 months now with pretty good success. I normally design underground power transmission lines, so I'm very familiar with Alignments and Profiles. I was recently asked to do a grading design for a new substation. The substation will be on two tiers, which will be separated by a retaining wall of some sort. I've watched some of the webinars and done the tutorials, so I'm somewhat familiar with basic grading.

This is my first grading project, so I'm trying to figure out what sort of deliverables I need to produce and what the drawings need to look like. Does anyone have any useful links to drawings that I could look at, and how the heck do you create a retaining wall??

Thanks in advance,

Ian

[kcobabe]

Well since I use to design substations I think I might be able to help you here.

First off you will need to know the TOCs of the foundations for the equipment going into the substation (Xfmr Pad, Bus supports, Cap Bank Fdns, PCBs Fdns, etc...)

You will then need to know where the control house (If your company uses one, which most do, but there are smaller utilites that use a metalclad SWGR and enclose relaying). You will also need to know where they are going to bend the bus as this is important for getting your grade break locations.

After that you will need to know which side the site will drain towards, driveways, sidewalks, landscaping, etc...

You will need to know the parcel dimensions.

After you have all of that information you can start.

Start by building pads for common TOCs of foundations. There may be a company standard for how far beyond fencing and equipment this will go. usually they want enough room to place a grounding mat which is 4'x4' typically out side of a fence gate. By the way this can be done with featurelines or plines, 3dpolys, which ever you choose, but I prefer feature lines. Also make sure you are doing all of this on the same site.

Build the footprint of the control house and/or major equipment. You will find that because of their size PCBs, XFMRs, SWGR, etc.. may have there own TOC for the foundation. I also do these with feature lines.

Now do the inside face of the wall with a feature line.

Finally the parcel lines with a feature lines

Now do a stepped offset command, you can find this on the feature line tool bar, for the wall.

Depending on the civil engineers taste you may have to tweek the grade, you can do this through the feature line editor in the panorama window.

Once you have everything where you want them you can start a new surface and add the lines as breaklines. You are now done.

Of course this is one of many ways to do it.

[Anonymous]

First, thank you for the response!

The TOC elevations for the equipment have been provided, and I know where the control house will be, so that is a start.

The upper tier will contain the switchyard, and the lower tier will contain the operating and maintenance equipment. So, there won't be any bus in the lower tier. The difference in elevation between the two tiers will be ~15 ft. There also must be a road that goes from the upper tier to the lower tier. The yard will be built into the side of a hill in a rural area, so we'll have to grade outside the yard as well to satisfy erosion requirements.

We've decided on a 1% grade inside the yard, and the runoff will be collected in an on-site oil separation pond.

I've heard of grading with just feature lines. Will this allow me to determine volumes, as the engineer wants me to balance the cut/fill?

Thanks again! Message was edited by: IanG

[Anonymous]

All of your volumes will be determined from your existing and proposed surfaces. Whether you use grading objects or feature lines does not matter. SAVE OFTEN!!

Fred Mitchell
APAI

[Anonymous]

Thank you for the reply. Any and all help is greatly appreciated.

Is it acceptable to use both feature lines and grading objects in the same drawing? I can see how feature lines can be used for on-site grading, but I also need to create a 2:1 slope from the site boundary to the existing surface. Should grading objects be used here?

Thanks!

[kcobabe]

yes,

About the only thing you cannot do with feature lines that you need the grading tools for is daylighting. It really doesn't matter because the featurelines and the grading objects will be placed in the same site and the will relate to one another.

All you have to do is add them to the surface when the surface is made from the daylighting grade. Do not try to make a surface then add the grading and feature lines after. Create the grading with automatic surface creation, unless the size is big then create the surface after, then add the feature lines to that surface.

[Anonymous]

Hello again! Thanks for the help!

I'm making pretty good headway on this now. I finally understand how the feature lines can be used to do most of the grading!

I forced the site to have 1% slopes for oil containment and drainage, and made a daylight slope of 2:1 from the site boundary to the existing ground. The only problem I'm running into is when I add breaklines to the surface that the daylight grade is on. The slopes and elevations change for some reason. I'll keep troubleshooting this...maybe I overlooked something.

Thanks!

[Anonymous]

Thanks again for the help, the grading is coming along pretty well now. The only problem I'm having now is doing the grading for a driveway. One end of the driveway will match existing grade, and the other part of the driveway will be on finished ground. Sooo, do I need to daylight to two different surfaces? What's the best way to approach this?? I attached a PNG so you can see what I'm talking about.

TIA, Ian

[Anonymous]

You could create a 'Finished composite surface'. Make a copy of 'OG' and
paste your design into it. Then your driveway design will only reference one
surface.


wrote in message news:5452201@discussion.autodesk.com...
Thanks again for the help, the grading is coming along pretty well now. The
only problem I'm having now is doing the grading for a driveway. One end of
the driveway will match existing grade, and the other part of the driveway
will be on finished ground. Sooo, do I need to daylight to two different
surfaces? What's the best way to approach this?? I attached a PNG so you
can see what I'm talking about.

TIA, Ian

[Anonymous]

Ahh, good idea. I'm guessing I can simply add my feature lines as break lines in the composite surface?

Thanks!

EDIT: I just found the Edits>Paste Surface button. I assmue that's the proper way of doing this. Message was edited by: IanG