Convert existing linework into feature lines. Many site features are drawn initially as simple linework for the 2D plan. By converting this linework to feature line information, you avoid a large amount of rework. Additionally, the conversion process offers the ability to drape feature lines along a surface, making further grading use easier.
Master It Open the MasteringGrading.dwg file from the data location. Convert the magenta polyline describing a proposed temporary drain into a feature line and drape it across the EG surface to set elevations.
Solution
1. From the Home tab’s Create Design panel, select Feature Lines Create Feature Lines From Objects.
2. Pick the polyline.
3. Toggle the Assign Elevations check box on.
4. Select the EG surface in the Assign Elevations dialog.
5. Click OK twice to close the dialogs and return to your model.
Model a simple linear grading with a feature line. Feature lines define linear slope connections. This can be the flow of a drainage channel, the outline of a building pad, or the back of a street curb. These linear relationships can help define grading in a model, or simply allow for better understanding of design intent.
Master It Add 100′ (30.48 m) radius fillets on the feature line you just created. Set the grade from the start of the feature line to the circled point to 5 percent and the remainder to a constant slope to be determined in the drawing. Draw a temporary profile view to verify the channel is below grade for most of its length.
Solution
1. Display the Feature Line toolbar’s Edit Geometry panel, and select the Fillet tool.
2. Pick the feature line.
3. Enter R↵ to change the radius.
4. Enter 100↵ (30.48 m) for the radius.
5. Enter A↵ to fillet all the points.
6. Toggle on the Edit Elevations panel and select Insert Elevation Point.
7. Use the Center osnap to pick the center of the circle. Press ↵ to accept the elevation.
8. From the Edit Elevations panel, select the Set Grade Between Points tool.
9. Pick the feature line. Pick the PI near the start of the feature line.
10. Press ↵ to accept the elevation. Pick the elevation point at the circle’s center.
11. Enter -5↵ to set the grade.
12. Pick the feature line again.
13. Pick the elevation point created near the circle. Press ↵ to accept the elevation.
14. Pick the PI at the downstream end of the channel. Press ↵ to accept the elevation.
15. Press ↵ to exit the command.
16. Pick the feature line. Right-click and select Quick Profile.
17. Select only the EG surface and Layout from the drop-down list in the 3D Entity Profile Style selection box.
18. Click OK and pick a point on the screen to draw a profile view.
Model planar site features with grading groups. Once a feature line defines a linear feature, gradings collected in grading groups model the lateral projections from that line to other points in space. These projections combine to model a site much like a TIN surface, resulting in a dynamic design tool that works in the Civil 3D environment.
Master It Use the two grading criteria just used to define the pilot channel, with grading on both sides of the sketched centerline. Calculate the difference in volume between using 6:1 side slopes and 4:1 side slopes.
Solution
1. From the Home tab’s Create Design panel, select Grading Create Grading to activate the Grading Creation Tools toolbar. Set Surface to EG.
2. Click the Set The Grading Group tool.
3. Check the Automatic Surface Creation option.
4. Check the Volume Base Surface option, select the EG surface, and click OK.
5. Click OK to accept the surface creation options.
6. Change Grading Criteria to Grade To Distance.
7. Click the Create Grading tool and pick the feature line.
8. Pick the left or right side. Press ↵ to model the full length.
9. Type 5′ (1.52 m) for the distance.
10. Press ↵ to accept 2 percent grade.
11. Pick the main feature line again and grade the other side.
12. Change Grade to Surface Criteria and grade both left and right sides, accepting the default values.
13. Right-click to complete the gradings.
14. Pick one of the diamonds in the grading. Right-click and select Grading Group Properties.
15. Switch to the Properties tab and note the volume (approximately 424 Cu. Yd. (12 Cu. M.) Net Fill). Click OK.
16. Right-click the diamond representing the Grade To Surface grading.
17. Click the Grading Editor tool.
18. Change Slopes to 4:1. Click OK.
19. Repeat for the other side of the channel.
20. Pick the diamond again and select Grading Group Properties. The new net volume is approximately 293 Cu. Yd. (8.29 Cu. M.) The difference is approximately 131 Cu. Yd. (3.71 Cu. M.).