NOTES Module 12 Site Grading and Quantities In this module, you learn how to grade a residential subdivision site and calculate cut and fill earthwork volumes in AutoCAD Civil 3D. Objectives After completing this module, you will be able to: Create and edit feature lines. Create an interim grading surface. Create feature lines from a surface and modify a design surface. Create a final grading surface and calculate earthwork volumes. Create reactive spot elevation and grade labels for the proposed surface. Generate data required for construction.AutoCAD Civil 3D 2009 Education Curriculum NOTES 12-2 Notes Data for this module resides in the \AutoCAD Civil 3D 2009 Education Curriculum\Module 12 – Site Grading and Quantities\ folder. Student Exercises The following exercises are provided in step-by-step format. Open the AutoCAD Civil 3D program prior to beginning the lesson by double-clicking the Civil 3D icon on your desktop. Those working in the Imperial system should use the drawing files beginning with the letter I, while those working in the metric system should use the drawing files beginning with the letter M. You are provided with a drawing for each exercise in the lesson. You are required to open the drawing provided with each lesson. The exercises in this module are as follows: 1. Create and Edit Feature Lines 2. Create Interim Grading Surface 3. Create Feature Lines from the Surface and Update Surface 4. Create Final Grading Surface and Calculate Volumes 5. Create Spot Elevation and Grade Labels 6. Generate Data Required for ConstructionModule 12 - Site Grading and Quantities NOTES 12-3 Site Grading and Quantities Site grading for a subdivision design is often an iterative and lengthy process. The most important design considerations for subdivision site grading are to ensure that rainwater drains off the site, and that the final earthwork volumes are balanced. Many times the designers purposely design the grading to generate excess fill material that can be used in another area of the site. The roads and the profiles for the subdivision usually dictate the overall grading and drainage characteristics for the site. For this reason, the roads are designed first. The next step is to grade the subdivision parcels. In this module, you design the grading for the subdivision parcels. The 3D elevations at the subdivision road right-of-way locations are used as a starting point to design the grading for the subdivision. The objects that represent the design elevations at the right-of-way locations are called feature lines. Feature lines are Civil 3D objects that are very similar to AutoCAD 3D polylines, except that they are far more powerful. The horizontal and vertical locations of feature lines are created, edited, and modified using the Civil 3D feature line tools. These are a powerful set of utilities that allow you to manipulate feature lines in ways similar to the AutoCAD polyline edit commands. You create property setback feature lines by offsetting the right-of-way feature lines horizontally and vertically. Using an interim grading surface, you also determine the feature line elevations at the edge of the site. This boundary feature line is then used to create Civil 3D grading objects, which project the design match slope to the existing ground surface model.AutoCAD Civil 3D 2009 Education Curriculum NOTES 12-4 The design feature lines and grading objects are then used to create the final design surface. The design surface can then be used to generate data for construction, such as staking points and plans that show the overall drainage characteristics of the site. Finally, to help you with this module, the following illustration shows referenced street names and directions.Module 12 - Site Grading and Quantities NOTES 12-5 Birch Lane is the west cul-de-sac and Cedar Cove is the east cul-de-sac. Key Terms Feature Line A feature line is a special line type that grading commands recognize and use as a footprint and surfaces can use as a breakline. You can draw feature lines, create them by converting existing objects, or export feature lines from corridors. Feature lines are similar to AutoCAD 3D polylines and store both horizontal and elevation location data. Feature lines can be labeled with grades and elevations. Feature Line Style The feature line style controls the appearance of a feature line. Grading Feature Line from Corridor You can create feature lines from corridors. Oftentimes, a designer creates a grading feature line at the corridor right-of-way locations. These feature lines are used to begin the grading for the subdivision parcels. Grading feature lines created from a corridor can either be dynamic, and automatically react with changes to the corridor, or they can be static, and therefore editable. Elevation Editor The Elevation Editor is displayed in the Panorama window and is used to modify the elevations of feature lines. You can modify individual elevation points or raise and lower the feature line by a specified distance. When you click an elevation point in the Elevation Editor, Civil 3D displays a graphic marker in the drawing area to show the location of the selected elevation point. Interim Grading An interim grading surface is created to model the overall drainage characteristics for the site. Feature lines can then be created at any locationAutoCAD Civil 3D 2009 Education Curriculum NOTES 12-6 Surface on the site and assigned elevations from the interim grading surface. Daylighting Daylighting refers to the action of projecting a slope from a feature line to a surface. The location where the projected slope intersects the surface is called the daylight line. Stepped Offset Stepped Offset is a feature line tool that offsets a feature line by a horizontal and vertical distance. You can also specify the offset parameters with a horizontal distance and a grade. Corridor Datum Surface The corridor datum surface represents the subgrade level of a corridor. It is included as data in the design site grading surface for earthwork volume calculations. Elevation Point An elevation point is a location on a feature line with an assigned elevation. Grading Object A grading object is a Civil 3D object that represents a projected slope to either a surface, elevation, or an offset. Grading objects are most often used to daylight to an existing surface. Grading objects
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