Parcel Creation – Lots & Blocks

I initially wrote this post in March of 2006, but I’m still finding it one of the more popular articles. The images may have changed, but the workflow is essentially the same.

Parcel creation in Civil 3D is tricky if your subdivisions require Lots and Blocks (Texas, for example). This assumes duplicate lot numbers inside a subdivision, and Civil 3D isn’t geared to handle duplicates. This condition also wreaks havoc on display order if you need to show a ROW as a different linetype/color. Stick with me, you won’t find this in a book, they won’t teach you this in class, and there aren’t any webcasts to cover this tricky situation – but it’s how many of us are required to work.

This is how I subdivide an area when lots and blocks are required:

1. Draw yourself a rectangle in C3D – make it 250′ deep by 300′ long. Explode the polyline. Offset the “north line 100′ south, then 50′ to define a ROW. This should yield the following:

2. Now using the BPOLY command, BPOLY the inside of the city block on the north.

3. Create a Site called “50″ representing “City Block 50″ within the subdivision. You can dig into the labels later. You’ll need to have defined object layers to match all of your conditions. These are the base layers – because the parcel objects physically reside on the base layers, you can control their visibility by changing the layer state. For example, if you turn off the base layer for surfaces, all surfaces are turned off in the drawing. I use the following layer names:

DC-BNDRY
DC-BNDRY-OUTBOUNDARY
DC-BNDRY-OUTBOUNDARY-SEGMENT
DC-BNDRY-CBLOCK
DC-BNDRY-CBLOCK-SEGMENT
DC-BNDRY-ROW
DC-BNDRY-ROW-SEGMENT
DC-BNDRY-LOT
DC-BNDRY-LOT-SEGMENT

The key to this process, and this a biggie: The layers in your City Block Style (found in the City Block Style on the “Display” Tab) must be set to “0″ for labels to have independent On/Off controls. In step 10 below, any labels will disappear unless you’ve done this.

Layer 0 has a special meaning in the Component Display settings . When the layer is set to 0, the object base layer is used for that component. For example, if the Parcel Segment base layer is DC-BNDRY-LOT-SEGMENT, and the “Parcel Segments” component layer (again – in the Parcel Style Dialog) is set to 0, then the parcel lines behave as if they are located on layer DC-BNDRY-LOT-SEGMENT (not layer 0).

4. Using the “Create from Objects” routine, create “City Block 50″ as shown:

Again – if you open DC DFW CITY BLOCK Parcel Style, you’ll find the component layers are set to 0 (zero).

5. Subdivide the City block into parcels using any method you choose to yield the following:

6. Notice you’ll have one parcel that needs a Style change, and the Site Parcel label (Site Parcels) will appear (once you’ve subdivided the entire City Block). By now you know you can change the styles with a right click, so do so. And by the way, the Site Parcel label will have a tendency to jump around once you close and re-open the drawing; I would recommend pinning it in place (Right Click on the label, select Label Properties, and change “Label is Pinned” to “TRUE”).

7. Now do the same for the City Block to the South to yield the following (after renumbering the parcels):

8. Turn your original subdivision outboundary lines into a subdivision “Parcel” (for lack of a better term).

9. This is sweet – select the city block label (by now you know it’s the Site Parcel label), right click, select Parcel Properties, move the City Block up in the display order.

10. Turn OFF the layer DC-BNDRY-CBLOCK-SEGMENT, don’t freeze it, turn it off. You can turn it on if you need to add labels, turn it off when you’re done – the labels will remain (assuming you’re lables exist on an independent layer, I use DC-BNDRY-CBLOCK-DIM).

11. Remember the original “ROW” lines you created with the offsets in step #1? Put them on layer DC-BNDRY-ROW-SEGMENT and set the linetype/color to reflect your standard and yield the following:

Need to add an alignment? Define it in its own Site as well:

With a little ingenuity, Civil 3D is rock solid; dig in.

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