Topo cut/fill reporting with pads?

[patricks]

I'm wondering about the cut/fill numbers my toposurface graded region is reporting.

I'm working on an addition to an existing building. The new and existing building finished floor is a couple feet above the grade around the building, so I have a pad set up to bring the grade underneath the building pad up to the underside of my building slab.

So in an existing view, I created a pad for the existing building, on the existing topo.

Then in a new view, I clicked on Graded Region and selected to copy internal points of the existing topo. When I did this, the pad under the existing building was also copied along with the toposurface. So now I have a pad created in New Construction underneath my existing building, with another toposurface extending up under that pad. I also have another pad under my new building, with a toposurface extending up under that pad, as well.

So, on my New Construction phase, I have a total of 3 toposurfaces. The overall site, and the surface underneath each pad.

When I check the Net Cut/Fill for the overall site, it's showing a net fill of 9570 CF. If I delete one of those pads (and its toposurface), the net cut/fill for the overall site toposurface INCREASES! Is this correct behavior? How do I know if the cut/fill number for the site toposurface is taking into account the fill required underneath my new slab, and NOT counting any fill under the existing building, since we're not touching that one?

[patricks]

Okay, it appears that the net cut/fill of the overall site toposurface does NOT include pads. The cut/fill increased when I deleted the pad, because the site topo filled in the area where the pad was before, and added that to the cut/fill total.

So to get an accurate cut/fill amount, you have to add your site topo cut/fill amount to the pad cut/fill amount for your NEW buildings only.

[iandidesign]

Can you clarify this a little for me please. Are you saying that when a pad is placed the pad area is then removed from the cut/fill altogether, essentially ignored? How then did you add the additional c/f from your pad areas into your calculation?

Thanks.

[patricks]

Can you clarify this a little for me please. Are you saying that when a pad is placed the pad area is then removed from the cut/fill altogether, essentially ignored? How then did you add the additional c/f from your pad areas into your calculation?

Thanks.

Just add your topo cut fill together with the cut/fill reported for the new pads.

[mthurnauer]

I have a project where I have three phases: Existing, Post Demo, and New Construction. The reason is that we have a grading plan for after an existing building is demolished. I want my topography schedule to indicate the amount of cut/fill based on comparing the grade at between the post-demo and new. I made the new grading by using the demo phase grading and creating a graded region and keeping internal points. What do I want my phase filter set to for the topography schedule? Just new? New and previous?

[twaldock]

Just add your topo cut fill together with the cut/fill reported for the new pads.

It seems that the cut and fill for the pad is not shown in the properties dialog box, so you have to create a topography schedule (even though Pads are "Site" category). In the schedule, it does not give you information about which item is the pad - so you have to be quite careful figuring out which is which.

This problem can be quite dangerous - a trap for new users (and very experienced users too!). We were caught out in a much simpler scenario with a new buiding:


Create a toposurface;
make it existing phase;
create a graded region, and it makes a new surface for you to modify;
check the cut and fill in properties for the new toposurface - all looks good;
Add a new construction pad; pad shows no cut'n'fill properties;
so we assumed that the amended cut and fill properties of the toposurface were correct for the whole site.
Wrong! It was only showing cut and fill for the area around the pad.


This is the sort of thing that can lead to litigation - you have been warned. Check and double-check.

[patricks]

The pad does not report cut and fill. The piece of topography immediately below the pad does. :)

A pad cuts a hole completely through your graded region, and places a separate piece of topography in that hole. That's the piece that reports the cut/fill for the area below the pad.

[twaldock]

Thanks for sorting that out. It makes more sense now, but is still a trap if you don't realise that the pad is chopping up the toposurface - so a schedule is the safer way to check the cut and fill, but you'd still need to double-check it to make sure which pieces of toposurface are included.
I can imagine that a site with dozens of different pads would be a nightmare to keep track of the cut and fill on. It would be useful if the parent toposurface kept a running total for all the little pieces chopped out of it by pads.

[bregnier]

I always make it standard practice to name every piece of topo, and include that in the schedule to sort out exactly what is going on. Revit is nice enough to provide an instance parameter for this very purpose :). FWIW the numbers that come out are really only appropriate for internal review - Revit has a very literal view of cut and fill, and the amounts it reports usually exceed those reported by a civil engineer for the same work.