Workflow for Grading Two Different Pad Elevations to Existing Grade

[dchen56]

Hello everybody! I am a college student working on my senior project. Basically, we have two separate pad elevations on top of an existing grade surface. Our goal is to grade these down to the existing grade surface.

We have already created two separate feature lines for the two pad footprints. Our thought process is to add these feature lines to the same site (called FG Pad), then create a grading group for this site, and create separate grading objects by selecting each feature line one at a time. Is this correct? So far, we have applied this methodology to the theater pad already and you can see the white grading object at the south end of the pad. The issue here is that it is not showing up as a green and red grading object, so we cannot see where the cut and fill regions are. I am imagining this has to do with the layer that the grading object is on, am I correct? 

Attached is our DWG file for reference. 

Thank you!

[Neilw_05]

You are on the right track. A few issues with your file:

1: If you want to see the slope patterns you will need to turn on the Slope Pattern option in the grading style for both cut and fill styles.. Also you will need to turn on Slope Patterns in the Display settings for the styles. 

2. Your grading from the bldg pad at 2% is crossing over itself in the corners. This happens when the grading does not intercept the target surface before it meets the slope coming from an adjacent segment. To address this situation you have a couple of options:

A. Create a gap in the grading at the corners so the projections come together at a common point before they cross. You can do this by choosing "No" when prompted to apply the grading to the full length of the bldg pad. You can then pick the start and end point of the grading to control where they meet. It is best to leave a small gap between the gradings and close it with a featurline, then use an infill in the enclosed open space at the corners to add surface triangles at the corners. Don't let them cross each other as that causes them to corrupt (a known issue with the software).

B. Draw a featureline around the daylight/tie-in points you are getting from the gradings, snapping to the vertices, then delete the gradings and use that as your tie in. Use an Infill to triangulate between the pad and the tie in. The TIN will form properly and not have the overlaps you get from the gradings. This solution is not dynamic to changes in the elevations of the pad, so any changes will require repeating the process.

This is too complex for you to understand in a textual explanation. If you understand what I am saying, see if you can make it happen. Otherwise let me know and I'll see what I can do when I have some time.

PS: If you want to have a surface and contours from the gradings, turn on the Automatic Surface option in the grading group properties. This will result in a surface model that is dynamic to changes in the grading group.

[dchen56]

Neil, thank you so much for your reply. I will take a stab at this and let you know if I have any questions.

[dchen56]

Hi @Neilw_05 ,

I am going to go with Option B. However, I am a little confused as to what boundaries I should put my feature lines around. I started drawing a polyline (which I will later turn into a feature line) around the vertices of the south end of the grading (directly south of the theater pad). The daylight lines of this region of the grading seemed simple enough to trace.

Some of the daylight lines of the theater appear to run underneath and even beyond the parking structure pad (which I have not created grading for yet). Should I still draw feature lines around these daylight lines for the theater grading? They are not connected to the grading region which I already drew feature lines around, so I would have to create separate feature lines, delete the entire grading region, and use the feature lines as tie-ins (not sure how to do the tie-in/infill part of the procedure). How can I ensure that the grading for the theater does not interfere with the grading for the parking structure?

Attached is the most recent version of my DWG. All I have changed is the layer that my grading object is on to C-TOPO-GRAD (which changed some of the region to green, but the rest of it is still white-which should be red if it is cut) and drew a polyline around the south end of the grading object for the theater (as described previously in the first paragraph). 

Thank you again for your time. I am very grateful for your support.

[Neilw_05]

Looking at your file again it is obvious your approach of grading out from the building at 2% until it daylights at the existing ground is not going to work. Site grading is rarely so simple. In this case you are constrained by the roads and parking lot around the N, S and W sides. You will need to match them with your grading. Your seamlines are the back of sidewalks for the roads and the edge of the parking lot. Establish those first to get your tie in elevations. If they are close to the building elevation you may be able to straight grade from the bldg to the seamline. If the slopes get too steep then you will need walls and maybe steps. In any case you will not be using the Grade to Surface grading, except for the east side, depending on whether there is a property line or other constraints.

My approach for this is to use the building outline as a Featureline that represents the dirt elevations at the building. The elevations can vary as needed to work with the adjacent seamlines. For the building slab, offset the perimeter FL a small amount and make that one be the finished floor elevation. Close off any gaps with feature lines and use infills to make the surface model form in the closed areas. When working with gradings, close off gaps and use infills vs. adding featurelines as breaklines whenever possible. That way you get automatic boundaries for the surface model.

As I said earlier, this gets to be too complicated to explain in a forum. It takes years of experience to learn how to address the many issues that come with site grading. That said, this is the best advice I can give for now. See if you can figure it out and if you have a specific challenge I might be able to help.