IntroductionOverviewFeature LinesWhat are Feature Lines?Using Feature Lines to Grade a SubdivisionCreating the Feature LinesSitesRulesProcessCreating a surface from the Feature LinesLabeling the DesignEditing the Feature LinesElevation Editor… Quick Elevation Edit Set Grade/Slope between Points Insert High/Low Elevation Point Insert PI Grading ObjectsWhat are Grading Objects?Using Grading Objects to Create a PondModeling the top of the pondModeling the bottom of the pondGrading the pondFinal pond combinationWatershed AnalysisWhat are watersheds?Using Civil 3D 2008 to delineate watersheds.ConclusionSubdivision Grading Made Easy: Grading Beyond the Roads Brian J. Hailey, PE – CAD-1 CV214-3P Residential subdivision grading can be a tedious task. Learn how to use the tools in AutoCAD Civil 3D 2008 to make this process faster, better, and less prone to errors. You will also learn to grade a detention pond that doesn't have a flat bottom. About the Speaker: Brian is a Product Support & Training Specialist for Cad-1 in Denver, Colorado, where he trains customers in Civil 3D, Land Desktop, Map, and AutoCAD and assists companies in Civil 3D implementation. Prior to working for a reseller, Brian was a soldier in the Army. He then graduated from Colorado State University in 1998, and for the next 8 years worked as a civil engineer, earning his professional engineering license in the state of Colorado.Subdivision Grading Made Easy: Grading Beyond the Roads 2 Introduction This 90 minute course will provide an in-depth look at the grading tools available for a standard residential subdivision design. It will guide attendees through the process of using feature lines, surfaces, and labels to grade the building sites, using the grading tools to design a detention pond, and using the surface analysis tools to perform a watershed analysis. This will allow the design professional to grade a site faster with fewer errors. Overview AutoCAD Civil 3D 2008 has a complete line of tools that can be used in the design of a residential subdivision as well as just about any other site. The style-based approach allows the user to quickly design the site and consequently make changes. During the design process, the labels for the grading are dynamically updated to the new design so the user can see the effect of the changes. Feature Lines What are Feature Lines? Feature lines are Civil 3D objects that are used to model the grading of a site. In essence, feature lines are 3d polylines on steroids. Like 3d polylines, they can have different elevations at each of their vertices; however, there are many advantages to using feature lines instead of 3d polylines. First, feature lines can have curves. 3d polylines can approximate a curve by placing vertices at an interval along the path of the curve; but this is just an approximation. If the elevation of the polyline needed to change, all the vertices would need to be updated or it would have to be recreated. With Feature Lines, since there is only two vertices for the curve, editing the elevations is a simple procedure (See Figure 1).Subdivision Grading Made Easy: Grading Beyond the Roads 3 Figure 1 The difference between a Feature Line and a 3d Polyline Next, feature lines have more robust editing tools than 3d polylines. There is an entire toolbar for editing and creating feature lines (See Figure 2). These tools vary from the Elevation Editor to the tools for placing high/low points and setting the grades. Figure 2 Feature Lines Toolbar Feature lines can have grade break points between the Points of Inflection (PI). When editing the feature line, these points allow a change in elevation; but they cannot be moved horizontally, except along the feature line itself. Finally, feature lines know what is happening in all the other feature lines in the site. If two feature lines cross or share a vertex and they reside in the same site, they cannot have a different elevation. Editing the elevation of one feature line will result in editing any other feature lines that it crosses. In contrast, if two 3d polylines cross, both polylines would need to be edited, introducing the possibility of error.Subdivision Grading Made Easy: Grading Beyond the Roads 4 Using Feature Lines to Grade a Subdivision Creating the Feature Lines Sites Sites within Civil 3D are used to collect things which relate to each other. The most common and well-known use of sites is for parcels. The parcels within a site have a relationship with each other. If one parcel line is moved, all affected parcels are updated. This same concept applies to feature lines as well. Feature lines within the same site are all linked together. If a feature line is added to the site or if a feature line within the site is modified, all the other feature lines conform to those changes. When dealing with parcel segments, these changes affect the horizontal layout of the parcels; however, with feature lines, the vertical geometry is what is important (See Figure 3). Figure 3 Feature Lines that cross in the same site cannot have different elevations at their intersection.Subdivision Grading Made Easy: Grading Beyond the Roads 5 Feature lines should be grouped together by the surface they will reside in. For example, if Block 14 of a site is being graded and a surface that is specific for that block will be created, the feature lines for that surface should go into a site for that surface, such as Site Block 14. Keeping separate sites like this will prevent geometry (feature lines, parcel segments, grading groups, and alignments) not intended for that surface from interacting with those feature lines. Rules When working with feature lines, there are several rules to follow. Probably the most important is to have good, clean geometry. For example, if a feature line ends at another feature line, have it end exactly at the intersection of the two lines. If the feature line extends beyond or ends short of the intersecting feature lines, it may be difficult to edit them (See Figure 4). One of the greatest, underutilized tools that come with Civil 3D is the Map Drawing Cleanup tools. These tools will take geometry that is close to being precise and make it precise. Use this tool on polylines prior to converting them to feature lines because the Map tools only work on native AutoCAD objects and not on Civil 3D objects. Remember, we don’t have to
View Full Document
Unlocking...