Assumptions: Corridor model has already been established; lot geometry has already been prepared including PAD set-back line. PAD elevations are already known, using TC formula to set minimum PAD elevations. This is purely a model building exercise!
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Starting with Defined Lot Geometry we can use the "Boundary" (Bpoly) command to create pad setbacks using a 20 foot set-back line from R/W. (See Figure 1.)
Figure 1
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Offsetting the original 2D pad polyline per the vertical side slope distance required, you can then use grips to adjust the down side lot to fit the required slope limits. Example: 2' vertical requires a 4' side slope at 2:1.(See Figure 2.)
Figure 2
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Using Grading > Polyline Utilities > Edit Polyline Elevations, set each pad to the required elevations for each lot pad. Working with Polylines instead of Feature Lines initially will keep you from working within the Sites Topology environment which in some cases can cause some drawing stability issues until you are ready to convert them to take full advantage of the editing functionality of Feature Lines. (See Figure 3.)
Figure 3
Elevated Polylines ready to be converted to Feature lines
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Extracting Back of Walk Feature Line from the Corridor will help to define the final PADS surface design. Once extracted, drawing Feature lines using Elevations from Pads and Back of walk draw in required slope transitions.
Figure 5
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Create Surface (P-PADS) Add in Lot Polylines and Transition Feature lines and Back of Walk Feature Lines to the definition. It is recommended that you add each group in individually so that is will be easier to edit or adjust per group. Build Surface. Cleanup any unwanted outside triangle lines to see completed surface. (See Figure below.)
Completed LOT Grading using only feature lines
Special thanks to Application Engineer, John Rodriguez of U.S. CAD for his help with lot grading using feature lines. For further information please contact me at melanie.santer@uscad.com or John Rodriguez at john.rodriguez@uscad.com
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Submitted by Melanie Santer, an application engineer for U.S. CAD, Inc. (formerly L.A. CAD), a large western-region reseller and Autodesk Authorized Training Center (ATC). Melanie has more than five years experience in the civil engineering industry, more than two years of practical field survey experience, and more than two years of land development/design experience on large commercial and industrial sites. Since joining L.A. CAD in 2005, Melanie has taught hundreds of public and custom classes using AutoCAD, Land Development Desktop, and Civil 3D and has been recently hired as an instructor at a local University. She is currently assisting more than 40 firms in California implement Civil 3D into their production environment.
