Back to Basics Pt. 7: Roadway Design in Civil 3D - Culverts, Cross Sections, & Drive

In this session, we will add culverts along our corridors and create cross-sections as well as cross-section sheets. We will also look at the drive function to view our finished corridors.

- Author Name: Ben Wardell
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Description:
From the existing ground contours, we can see a few areas where we will need to add culverts. We can also utilize our profiles to determine the low points of the existing ground. We will add 3 culverts to our design file.
To do this, We will pick a pipe network from the home menu and will choose to create a pipe network. We select the main alignment and specify the existing ground surface, as well as our view parameters.

IN the pipe dialog box we can specify the size of the pipe we want the layout. When we choose the pipe catalog, we can specify the type of network. In this case, we will use a storm drain. If we don’t see the size of the pipe we need we can expand the sizes available by adding all the pipes from the catalog.

Once we have determined the culvert type and size (in this case we want to add a 48 x 48 concrete box culvert) and the headwall type we pick the invert and outlet locations in our CAD file. The culvert appears with labels. We can adjust the head wall rotation and move the labels so they can read easier. And we will do the same thing for the other culvert locations as well. For these items, we will change the size and material. We will adjust the labels for these as well.

Near the end of the roadway, we will add an inlet since we are in a cut condition and outlet to the other side. Keep in mind that when we place the culvert, the elevation is based on the item we snap to – in this case, the existing ground contour.

Now we will set up the sample lines that will dictate the location of our cross-sections. We choose SAMPLE LINES, then specify the station range in the dialog box. We can adjust the begin and end values or select the locations in the file. We will also place additional sample lines at each culvert crossing that we added. We can adjust these to the exact location, length, and skew angle after we have the lines drawn. To do this we select the line and use the grips to adjust the center location and the endpoints to match our culvert. We can also extend the pattern lines sample lines to widen the display area of these sections.
And once we have our pattern line set up we can create the cross-sections. We do this by selecting section views in the home menu and we will pick CREATE MULTIPLE VIEWS since we have several sections we want to create. We select the size and scale of our sections as well as several other display settings. We’ve selected all the sample lines to include the culvert crossings. This is also where we would set up our display settings to show the slope and offset values based on the code sets in the corridor.

As we view the sections we can look for any areas that may not be modeled correctly. One of the pipe sections doesn’t have enough clearance so we can select the culvert in the section view and edit the size. The section will automatically update in the section view. In this area, we want to change our corridor model by creating a cut ditch on both sides. So we will revise the assembly and rebuild the corridor. We can also adjust some of the information on the inlet structure to make it a drop inlet or an end section. We also need to adjust the invert elevation so that it matches the ditch flowline. Again, once we update the invert elevation our pipe section updates automatically.

The sample lines are dynamic so if we make any adjustments to the lines our cross-sections will update automatically.
We can change the SKU angle of our sample lines and those updates to reflect the changes as well.

Once we have all of our sections in order, we can create cross-section sheets. The sheets will be based on our current set up. C3D will tell us to save the file before we create the sheets. If we discover the sheets are the wrong scale we can select a view port and choose the drop-down arrow in the center and change the scale of the window as well as the size. Everything looks good here.

We’d like to run the DRIVE command to inspect our corridors. Before we can do that we need to create the surface based on our design corridors. We select the corridor and choose the corridor surface. We can select the different elements from our corridor to base the surface upon. Some of these elements are the pavement, cut/ fill limits, and the sidewalks or curb & gutters.