C values - Impervious Surfaces

[Anonymous]

Does anyone know of an Automated way of generating C values or Impervious Surface areas easily using Civil 3d? We've been generation polylines around the areas then converting them to parcels to keep track, but that's a pain on a large site.

[Anonymous]

If each were it's own unique surface, then the surface information would give you your areas.

[annw2]

I haven't tried this in 3d yet, but in LDD, I start with the watersheds from the tin model. This generates easily 20 x the fnal data, but is useful for finding high points in flat areas.

Once I have the drainage areas drawn and erased all the extra junk from the watersheds, I use the parcel command to label the drainage areas.

(I tried this in 3d once & had it subtract out the area of the label. Haven't had a chance to try again with answer I got here.)

I then isolate layers for soil types & coverage & use the BPOLY command for the coverage subareas. I use the AREA of Last to get the area & transfer to a spreadsheet that automatically looks up the CN & AI and calcs the weighted unit average.

[Anonymous]

Look in to using Topologies through the Map tools. Works great, but to
involved to explain over a post...

--
mspatz, P.E.

[Anonymous]

do tell... i guess I gotta look into this know. thanks for the tip

paul

[tweaverGYRN7]

Give this a try... https://www.youtube.com/watch?v=xRo0eSXWsKE