Using Multiple Baselines

Up to this point, every corridor you've built has had a single baseline. When you worked with corridor surfaces, you were working with a complex corridor with multiple baselines. A cul-de-sac by itself can be modeled in two baselines, as shown in Figure 10.5. The procedures that follow will work for most cul-de-sacs, including symmetrical, asymmetrical, and hammerhead styles. You will need a centerline alignment and design profile for the road leading into the cul-de-sac as well as an edge of pavement (EOP) alignment and design profile defining the cul-de-sac bulb.

In the example shown in Figure 10.5, the centerline of the road, Baseline 1, will require a typical crowned assembly, which will terminate when it reaches the point in the cul-de-sac geometry where the bulb defining curvature begins. From that point, the baseline is swapped out for an alignment and profile that define the edge of the cul-de-sac.

As you've seen, when assemblies are applied to a baseline, the geometry of the subassemblies project perpendicularly from the baseline. In the example of Figure 10.5, the curb and gutter subassembly as well as the rest of the subassemblies it carries (sidewalk, daylighting) need to be projected from the edge of the cul-de-sac bulb because that's the way their real-life counterparts are built. The assembly used on this baseline will have the curb and gutter subassembly on one side and the lane subassembly on the opposite side (Figure 10.6). The lane subassembly will stretch to meet the centerline alignment and profile as its targets.

It helps to think of the assembly as radiating away from the baseline, from the assembly base outward, toward a target (Figure 10.7). Because the assemblies are applied to the baseline in a perpendicular manner, using the edge of pavement for a baseline in curved areas (such as cul-de-sac bulbs or curb returns) will result in a smooth, properly graded pavement surface.

Establishing EOP Design Profiles

One of the most challenging parts of complex corridor (i.e., cul-de-sac, intersection, or roundabout) is establishing design profiles for non-centerline alignments. You must have design profiles for both the centerline and edge of pavement alignments, but it does not have to be a painful process to obtain them.

Using a simple, preliminary corridor and the profile-creation tools you learned about in Chapter 7, “Profiles and Profile Views,” you'll find that establishing an edge of pavement profile can go quickly.

In the exercise that follows, you will work through the steps of creating an EOP profile:

1. Open the 1002_EOPProfile.dwg (1002_EOPProfile_METRIC.dwg) file, which you can download from this book's web page, www.sybex.com/go/masteringcivil3d2015.

   This drawing contains the corridor you worked on in the last exercise, plus an additional baseline and region built for ROAD E. You may also notice that there is an alignment tracing around what would be the edge of pavement in the cul-de-sac for ROAD E.

2. Click the corridor, and open Corridor Properties from the contextual ribbon.
3. On the Surfaces tab of Corridor Properties, do the following:
4. 1. Click the Create A Corridor Surface button.
   2. Rename the surface to North River Crossing - Top.
   3. Change the surface style to Border Only.
   4. Under Add Data, verify that the Data Type setting is set to Links and the Specify Code setting is set to Top.
   5. Click the Add Surface Item button.

   You will not be adding a boundary at this time.

5. Click OK to close the Corridor Properties dialog and rebuild the corridor when prompted.

   You should now see a green surface boundary in your drawing.

6. Press Esc to clear the selection. Select the red edge of pavement alignment for the cul-de-sac, and in the Alignment contextual tab Launch Pad panel, click Surface Profile.
7. In the Create Profile From Surface dialog, highlight North River Crossing - Top and click Add.
8. Click the Draw In Profile View button.
9. Leave all the defaults in the Create Profile View dialog and click Create Profile View.
10. Click in the graphic to the right of the surface to place the profile view.

    The profile you are seeing has a large gap in the middle. The two short segments at the beginning and end of this profile show what the proposed grade would be according to the corridor surface, which terminates at the PC and PT of the cul-de-sac bulb. The cul-de-sac alignment actually overlaps the corridor surface so you were able to show the proposed grades in profile view leading into and exiting the cul-de-sac.

    Next, you will fill in the large gap with your own profile by snapping to the red profile segments to ensure that you are matching grade at the edge of pavement of your cul-de-sac.

11. Select the profile view. (Hint: Click a grid line rather than the profile itself.) From the Profile View contextual tab Launch Pad panel, click Profile Creation Tools.
    1. For Name, prefix the alignment name with FG instead of XG.
    2. For Profile Style, select Design Profile.
12. Click OK to accept the defaults in the Create Profile dialog.
13. Snap to the end of the first red segment where the preliminary surface ends (station 0+00, elevation 9.149 or 0+000, elevation 2.784 for metric).
14. Next, snap to the beginning of the last red segment where the preliminary surface begins (station 3+69.17, elevation 9.149 or 0+113.26, elevation 2.784 for metric). Press Esc to deselect.

    You'll now add a high point along the corridor edge of pavement.

15. Click the Insert PVIs – Tabular button on the Profile Layout Tools toolbar.
16. Enter station 1+62.04 and elevation 11.58 (or station 0+049.54, elevation 3.528 for metric).
17. Close the Profile Layout Tools toolbar.

    Your profile should look like Figure 10.8.

    

You now have a proposed profile that is acceptable to use in the cul-de-sac baseline. Check your work against 1002_EOPProfile_FINISHED.dwg or 1002_EOPProfile_METRIC_FINISHED.dwg to see how your stations and elevations compare. You do not need to save the drawing file.

Putting the Pieces Together

You have all the pieces in place to perform the first iterations of this cul-de-sac design.

The following exercise will walk you through the steps to put the cul-de-sac together. You will complete several steps and let the corridor build to observe what is happening at each stage. This exercise will also encourage you to get comfortable using the Corridor Properties dialog to make design modifications.

1. Open the 1003_Cul-de-SacDesign.dwg (1003_Cul-de-SacDesign_METRIC.dwg) file, which you can download from this book's web page.
2. This drawing contains the cul-de-sac centerline alignment and profile, the EOP alignment and profile, and the assemblies needed to complete the process.
3. Click the corridor.
4. From the contextual tab Modify Corridor panel, click Add Baseline.
5. In the Create Corridor Baseline dialog, select ROAD E CUL-DE-SAC from the drop-down list. Click OK to continue.
6. In the Select a Profile dialog, select FG-ROAD E CUL-DE-SAC from the drop-down list. Click OK to continue.
7. From the contextual tab Modify Region panel, select Add Regions.
8. At the Select a baseline: prompt, click over the cul-de-sac alignment in the drawing.
9. At the Specify the region start station: prompt, type 0 ↵ Alternatively, you could snap to the end of the corridor at this location.
10. At the Specify the region end station: prompt, type 369.17 (113.26 for metric) ↵. Alternatively, you could snap to the edge of the corridor at this location.
11. In the Create Corridor Region dialog, under Assembly, select Curb Returns from the drop-down list. Click OK to continue.
12. In the Target Mapping dialog, in the Object Name column, click <None> next to Target Surface and select Existing Surface from the drop-down list in the Pick A Surface dialog. Click OK to dismiss the Pick A Surface dialog, and click OK again to dismiss the Target Mapping dialog.
13. Press the Esc button on your keyboard to end the command.

    The curb return assembly has been wrapped around the cul-de-sac, as shown in Figure 10.9. However, the curve frequency needs to be increased to mimic the curvature of the cul-de-sac bulb. Also, an offset and elevation target will have to be set so that the pavement of the assembly stretches to connect horizontally and vertically to the centerline design of ROAD E.

    

14. On the contextual tab, Modify Region panel, select Edit Frequency.
15. At the Select a region to edit: prompt, click anywhere inside the cul-de-sac portion of the corridor. Be careful not to select inside the “donut hole” in the center of the cul-de-sac.
16. In the Frequency To Apply Assemblies dialog, change the Curve Increment value to 5 (1.5 for metric). Click OK to dismiss the dialog.
17. Press the Esc key to end the command.
18. To stretch the pavement to meet the horizontal and vertical centerline of ROAD E, on the contextual tab Modify Region panel, select Edit Targets.
19. At the Select a region to edit: prompt, click anywhere inside the cul-de-sac portion of the corridor. Be careful not to select inside the “donut hole” in the center of the cul-de-sac.
20. In the Target Mapping dialog in the Width or Offset Targets section, click in the Object Name column next to Width Alignment. Note the name of the subassembly in the Subassembly column.
21. In the Set Width Or Offset Target dialog, under Select Alignments, click ROAD E.
22. Click the Add button to place it on the list below.
23. Click OK to continue.
24. Back in the Target Mapping dialog in the Slope or Elevation Targets section, click in the Object Name column next to Outside Elevation Profile. Note the name of the subassembly in the Subassembly column.
25. In the Set Slope Or Elevation Target dialog, select ROAD E as the alignment.
26. Under Select Profiles, choose FG-ROAD E and click the Add button to place it on the list below. You may need to change the width of the Name column to see the full profile name.
27. Click OK to dismiss the dialog.
28. Click OK again to close the Target Mapping dialog.
29. The corridor is completely modeled (see Figure 10.10).

    

30. With the corridor still selected, open Corridor Properties from the contextual tab.
31. On the Parameters tab, inspect the baselines and regions that are accumulating in your corridor, as shown in Figure 10.11.

    

The files 1003_Cul-de-SacDesign_FINISHED.dwg and 1003_Cul-de-SacDesign_METRIC_FINISHED.dwg are available for you to check your work.

Troubleshooting Your Cul-de-Sac

People make several common mistakes when modeling their first few cul-de-sacs:

1. Your cul-de-sac appears with a large gap in the center. If your curb line seems to be modeling correctly but your lanes are leaving a large empty area in the middle (see Figure 10.12), chances are pretty good that you forgot to assign targets or perhaps assigned the incorrect targets.

   

   You can fix this problem by opening the Target Mapping dialog for your region and checking to make sure you assigned the road centerline alignment and FG profile for your targets. Also, check to see if you assigned these targets to the wrong subassembly.

   To pinpoint the location of errors, use the Edit Targets tool from the Modify Region panel of the Corridor contextual ribbon. Edit targets one region at a time to avoid confusion.

2. Your cul-de-sac appears to be backward. Occasionally, you may find that your lanes wind up on the wrong side of the EOP alignment, as shown in Figure 10.13. The direction of your alignment will dictate whether the lane should be on the left or right side. In the example from the previous exercise, the alignment was running counterclockwise around the cul-de-sac bulb; therefore, the lane was on the left side of the assembly.

   

   You can fix this problem by changing the assembly applied to the region to one that was created for the correct side or reversing the alignment.

3. Your cul-de-sac drops down to 0. A common problem when you first begin modeling cul-de-sacs, intersections, and other corridor components is that one end of your baseline drops down to 0. You probably won't notice the problem in plan view, but once you build your surface or rotate your corridor in 3D (see Figure 10.14), you'll see it. This problem will always occur if your region station range extends beyond the proposed profile.

   

4. To fix this problem, make sure your region station range corresponds with the design profile length. You may need to extend the design profile in some cases, but usually restricting the station range of the region will do the trick.
5. Your cul-de-sac seems flat. When you're first learning the concept of targets, it's easy to mix up baseline alignments and target alignments. In the beginning, you may accidentally choose your EOP alignment as a target instead of the road centerline. If this happens, your cul-de-sac will look similar to Figure 10.15.

   

6. You can fix this problem by opening the Target Mapping dialog for this region and making sure the target alignment is set to the road centerline and the target profile is set to the road centerline FG profile.

Using the Intersection Wizard

All the work of setting baselines, creating regions, setting targets, and applying the correct frequencies can be done manually for an intersection. However, Autodesk® AutoCAD® Civil 3D® software contains an automated Intersection tool that can handle many types of intersections.

On the basis of the schematic you drew of your intersection, your main road will need several assemblies to reflect the different road cross sections. Figure 10.19 shows the full range of potential assemblies you may need in an intersection and the design situations in which they may arise.

This exercise will take you through building a typical intersection with a couple of right-turn lanes using the Create Intersection Wizard:

1. Open the 1004_Intersection.dwg (1004_Intersection_METRIC.dwg) file, which you can download from this book's web page.

   You'll start by building a four-way intersection for ROAD A and ROAD D.

2. From the Home tab Create Design panel, choose the Intersections Create Intersection tool.
3. At the Select intersection point: prompt, choose the intersection of the two existing alignments. (Hint: The Intersection Osnap will automatically turn on and be active.)
4. At the Select main road alignment <or press enter key to select from list>: prompt, click the ROAD A alignment that runs from west to east.

   The Create Intersection – General dialog will appear (Figure 10.20).

   

5. Set Intersection Corridor Type to All Crowns Maintained and click Next.
6. In the Geometry Details page (Figure 10.21), verify that ROAD A is the primary road by looking at the Priority list. If ROAD A is not at the top of the list, use the arrow buttons on the right side to reorder the roads.

   

7. Click the Offset Parameters button, and do the following in the Intersection Offset Parameters dialog:
   1. Set the offset values for both the left and right sides to 14′ (4.5 m) for both ROAD A and ROAD D.
   2. Fill in the check box for Create New Offsets From Start To End Of Centerlines. This will ensure that the turn lanes you're about to create will have targets to meet.

      At this step, the screen should resemble Figure 10.22.

      

   3. Click OK to close the Intersection Offset Parameters dialog.
8. On the Geometry Details page, click the Curb Return Parameters button to enter the Intersection Curb Return Parameters dialog.
   1. For the NE and SW quadrants, place a check mark next to Widen Turn Lane For Incoming Road.

      You will be creating right-turn lanes for ROAD A. Notice how the dialog changes when the check box is filled to show widening parameters.

   2. Click the Next button at the top of the dialog to move from quadrant to quadrant.

      You will see a schematic name of the quadrant listed at the top of the dialog that corresponds to the glyph. As shown in Figure 10.23, the temporary glyph will help you determine which quadrant you are currently modifying.

      

      When you reach the last quadrant, you will see that the Next button is grayed out. This means that you have successfully worked through all four curb returns.

   3. Click OK to return to the wizard's Geometry Details page.

      Some locales require that lane slopes flatten out to a 1 percent cross-slope in an intersection. If this is the case for you, you can change the lane slope parameters in the Intersection Lane Slope Parameters dialog (Figure 10.24). In this exercise you will leave this setting at -2%.

      

      Civil 3D performs the task of generating the curb return profile. The profile will be at least as long as the rounded curb plus the turn lanes that are added in this exercise. If you wish to have Civil 3D generate even more than the length needed, you can specify that in the Intersection Curb Return Profile Parameters dialog (Figure 10.25). This dialog is actually a series of dialogs based on quadrant, as was the Curb Return Parameters dialog. According to Figure 10.25, the alignment and profile for the SE - Quadrant curb return will be extended 25′ beyond its PCs and PTs. And how is this useful? You'll find out in the upcoming section called “Manual Intersections.”

      

      You will be keeping all default settings in both the Lane Slope Parameters area (Figure 10.24) and the Curb Return Profile Parameters area (Figure 10.25).

9. Click Next to continue to the Corridor Regions page of the Create Intersection Wizard (Figure 10.26).

   

   The Corridor Regions page is where you control which assemblies are used for the different design locations around the intersection. Clicking each entry in the Corridor Region Section Type list will give you a preview of what each assembly type should look like and where in the intersection it's applied (as shown at the bottom of Figure 10.26). If your assemblies have the same names as the default assemblies, they will be pulled from the current drawing. Alternatively, you can click the ellipsis to select any assembly from the drawing, which is what you will be doing in this example.

   If you didn't have all the necessary assemblies created in your drawing at this point, you could still create your intersection with the default assemblies. You could always modify the default assemblies with your own criteria and subassemblies after they are brought in.

10. On the Corridor Regions page, do the following:
    1. Click Add To An Existing Corridor to place the intersection in the North River Crossing corridor.
    2. Verify that Select Surface To Daylight is set to Existing Surface.
    3. In the Corridor Region Section Type list, set the following:

       Corridor Region Section Type	Assembly To Apply
       Curb Return Fillets	Curb Returns
       Primary Road Full Section	Full Section
       Primary Road Half Section - Daylight Left	Left Half
       Primary Road Half Section - Daylight Right	Right Half
       Secondary Road Full Section	Full Section
       Secondary Road Half Section - Daylight Left	Left Half
       Secondary Road Half Section - Daylight Right	Right Half

    4. Giving each assembly a friendly, meaningful name will keep things less confusing.
11. Click Create Intersection.

    After a few moments of processing, you will see a corridor appear at the intersection of the roads. Use the REGEN command if you do not see the frequency lines. Your corridor should now resemble Figure 10.27.

    

12. Select the corridor, and from the Corridor contextual tab Modify Corridor panel, select Corridor Properties.
    1. Switch to the Parameters tab of the Corridor Properties dialog and highlight one of the regions toward the bottom in the list, as shown in Figure 10.28.

       

       Notice how the region highlighted in the Parameters tab is outlined in the graphic. This will help you determine which region to edit.

       To move from region to region without searching through the overwhelming list of baselines and regions, use the Select Region From Drawing button.

    2. Click Cancel to close Corridor Properties and press Esc to deselect.

       Next you will create a three-way intersection.

13. In your drawing, pan northward to the intersection of ROAD C and ROAD D.
14. From the Home tab Create Design panel, choose the Intersections Create Intersection tool.
15. At the Select intersection point: prompt, choose the intersection of the two existing alignments.

    You will not be prompted to pick a main/primary road alignment for three-way intersections. The Intersection tool automatically configures the through road as the primary road.

16. On the General page of the Intersection wizard, set the Intersection Corridor Type to All Crowns Maintained and click Next.
17. On the Geometry Details page, accept the defaults and click Next.
18. On the Corridor Regions page, do the following:
    1. Click Add To An Existing Corridor to place the intersection in the North River Crossing corridor.
    2. Verify that Select Surface To Daylight is set to Existing Surface.
    3. In the Corridor Region Section Type list, set the following:

       Corridor Region Section Type	Assembly to Apply
       Curb Return Fillets	Curb Returns
       Primary Road Full Section	Full Section
       Primary Road Half Section - Daylight Left	Left Half
       Primary Road Half Section - Daylight Right	Right Half
       Secondary Road Full Section	Full Section
       Secondary Road Half Section - Daylight Left	Left Half
       Secondary Road Half Section - Daylight Right	Right Half

    4. Before creating this intersection, click the Save As A Set button so this configuration of assemblies can be reused on the other two three-way intersections.
    5. Name your file NorthRiver and click Save to continue.
19. Click the Create Intersection button to add this intersection to the North River Crossing corridor.
20. Repeat steps 15–19 for the intersection of ROAD C and ROAD B with the following exceptions:
    1. On the Intersection Offset Parameters dialog, turn off Create New Offsets From Start To End Of Centerlines.
    2. On the Corridor Regions page, click Browse to choose the assembly set you just created.
    3. In the Select Assembly Set File dialog, select the NorthRiver.xml file and click Open to import.

       This may take a few seconds, so wait for it.

    4. Do not forget to add the intersection to the North River Crossing corridor.
    5. Create the intersection.
21. Repeat steps 15–19 for the intersection of ROAD A and ROAD E with the following exceptions:
    1. You will not need to browse for the assembly set. The wizard will remember the last assembly set used.
    2. Do not forget to add the intersection to the North River Crossing corridor.
    3. Create the intersection.

       You should have four intersections in addition to your cul-de-sac modeled in your drawing, as shown in Figure 10.29.

       

22. Save and close the drawing when you have completed the exercise.

    The files 1004_Intersection_FINISHED.dwg and 1004_Intersection_METRIC_FINISHED.dwg are available for your review.

Creating Intersections Manually

You will begin this section by visiting an intersection with unusual circumstances that must be built manually. Then we will discuss other issues you can experience with intersections.

1. Open the 1004_Intersection_FINISHED.dwg (1004_Intersection_METRIC_FINISHED.dwg) file, which you can download from this book's web page.
2. Zoom into the intersections of the ROAD A and ROAD B alignments.
3. From the Home tab, on the Create Design panel Intersections tool, select Create Intersection and pick the intersection of ROAD A and ROAD B.
4. At the Select main road alignment <or press enter key to select from list>: prompt, click the ROAD A alignment that runs from west to east.
5. On the General page of the Create Intersection Wizard, for Intersection Corridor Type select All Crowns Maintained. Then click Next.
6. On the Geometry Details page, you'll be using the defaults for all parameters, so click Next.
7. On the Corridor Regions page, do the following:
   1. Turn on Add To Existing Corridor.
   2. Set the assemblies to the following:

      Corridor Region Section Type	Assembly to Apply
      Curb Return Fillets	Curb Returns
      Primary Road Full Section	Full Section
      Primary Road Half Section - Daylight Left	Left Half
      Primary Road Half Section - Daylight Right	Right Half
      Secondary Road Full Section	Full Section
      Secondary Road Half Section - Daylight Left	Left Half
      Secondary Road Half Section - Daylight Right	Right Half

   3. Click Create Intersection.

   The intersection will be created. Event Viewer will open displaying a number of errors, as shown in Figure 10.30.

   

   Upon looking through the errors in Event Viewer, you'll discover that they are all the same error occurring at different stations. Each mentions a target object not being found. The subassembly involved is LaneSuperelevationAOR and the Target name is Outside Elevation. Since the Intersection tool uses profiles for elevation targets, there must be a problem with one of the profiles that the tool created. A quick way to figure out which one(s) would be to examine the intersection in 3D.

8. On the ribbon, make the View tab current and do the following:
   1. On the Model Viewports panel Viewport Configuration tool, select Two: Vertical to split your drawing window into two viewports.
   2. Click in the right viewport to make it current.
   3. On the Views panel Named View list, make the 3D named view current.

   Your viewport configuration should be similar to Figure 10.31.

   

   For some reason, you have two quadrants in this intersection that decided to set down at elevation zero. You could spend a lot of time trying to seek out the reasons for this, but if you're like most of us, you're in a time crunch and would like to finish up this roadway model. Before we delve into creating manual intersections, it's important that you look at a couple of things before moving on.

   If you look at the profile properties for both the NE and SE quadrants on the Prospector under Alignments Curb Returns, you'll see that the profile is empty of station and elevation data (Figure 10.32), so this is one area where the Intersection tool failed. However, according to the errors, the targeting problems are occurring along the ROAD B baseline, so what is happening there?

   

   If you open up Corridor Properties, scroll all the way down to the bottom of the list on the Parameters tab, select one of the regions, click the Target ellipsis, and open the Set Slope Or Elevation Target dialog for the left lane, you'll see that the “bad” profiles show up for targeting there as well.

   Even if you made manual overrides to cause your corridor to use relevant data, you will still receive errors in Event Viewer because the Intersection tool does not want to let go of the profiles and settings it created. The upside to this behavior is that autogenerated intersections will always update. The downside to this behavior is when you are in situations like this where the tool failed in an area and you need to make manual adjustments. The best thing to do here is to “turn the intersection off.” The Intersection tool did do a lot of the heavy lifting for you, so all is not lost.

9. Press the Esc key a few times to make sure nothing is currently selected. This is always a good thing to do when you are about to press the Delete key.
10. In the left viewport, click the intersection marker (X with a circle imposed at the center). When you do so, the Intersection contextual ribbon will appear.

    Examine the contextual ribbon. Notice the tools for editing offset, curb return, lane slopes, and curb return parameters. If any of the parameters set in the Intersection wizard need to change, these tools can be used to reconfigure the intersection.

11. Press the Delete key.

    The contextual ribbon closes, the intersection marker and label disappear, and the entry for this intersection on Prospector will no longer be found.

    The next step is to re-create the two curb return profiles with relevant station and elevation data.

12. In Prospector, in Alignments Curb Return Alignments, right-click ROAD A-ROAD B - NE Quadrant and choose Select.
13. Select Surface Profile from the Launch Pad panel on the contextual ribbon.
14. In the Create Profile From Surface dialog, do the following:
    1. Under Select Surfaces, select North River Crossing Surface - Top.
    2. Click the Add button to add it to the profile list.
    3. Click Draw In Profile View.
15. In the Create Profile View dialog, click Create Profile View and place the profile in an open area in your drawing.

    If you take a look at the profile, the surface that is being displayed in profile is doing exactly what your corridor is doing: taking a dive down to elevation 0 where the quadrant begins and ends. Here is where you get to fill in the gap again.

16. On the Home tab Create Design Panel, select Profile and open the Profile Creation Tools.
17. At the Select profile view to create profile: prompt, select the profile view for the curb return.
18. In the Create Profile dialog, change the text in the Name field to FG-<[Alignment Name]>. Click OK to continue.
19. On the Profile Layout Tools toolbar, select Draw Tangents, and using your Endpoint Osnap, bridge the gap as shown in Figure 10.33.

    

20. Press ↵ to end the command. Close the Profile Layout Tools toolbar.

    You have created an actual profile that can be used in the NE quadrant of this intersection. Next, you'll address the SE quadrant.

21. Repeat steps 12–20 for the curb return alignment called ROAD A-ROAD B - SE Quadrant.
22. Using the left viewport, pan back over to the troubled intersection.
23. Select the corridor to reveal the contextual ribbon.
24. On the contextual ribbon, select Corridor Properties and do the following:
25. 1. On the Parameters tab, locate BL - ROAD A-ROAD B - NE - Quadrant (the name of the baseline may have a counter behind it depending how many times the Intersection command was executed). It may be helpful to simplify the list using the Collapse All Categories button in the top left of the dialog. You may use the Select Region From Drawing button as an alternative to searching the list.
    2. In the Profile column, click the profile name for that baseline to change the selection.
    3. In the Select A Profile dialog, change the selection to FG-ROAD A-ROAD B - NE - Quadrant. Click OK to continue.
    4. Next, locate BL - ROAD A-ROAD B - SE - Quadrant.
    5. In the Profile column, click the profile name for that baseline to change the selection.
    6. In the Select A Profile dialog, change the selection to FG-ROAD A-ROAD B - SE - Quadrant. Click OK to continue.
    7. Click OK in the Corridor Properties and rebuild the corridor if prompted.

    Event Viewer will pop up.

26. In Event Viewer, clear all the events being reported using the Action button.

    Although the right viewport is now showing a good-looking intersection, you'll want to take the following steps to ensure that Event Viewer isn't picking up any more problems with the corridor.

27. On the contextual ribbon, on the Modify Regions tab, select Edit Targets.
28. At the Select a region to edit: prompt, select the RG - Full Section region along ROAD B north of the intersection, as indicated by Figure 10.34.

    

29. In the Target Mapping dialog, under Slope Or Elevation Targets Outside Elevation Profile for the Left assembly group, click in the Object Name column.
30. In the Set Slope Or Elevation Target dialog, do the following:
    1. In the Selected Entities To Target section, select both profiles on the list.
    2. Click the Delete Selected Item button to remove both profile targets from the list.

       Neither of these targets are needed since you are not widening the road in this area.

    3. Click OK to close.
31. Click OK to close the Target Mapping dialog.

    The Select a region to edit: prompt should still be active.

32. Select the RG - Left Half region in the north part of the intersection along ROAD B, as indicated by Figure 10.35.

    

33. Repeat steps 28–30. Just be aware that sometimes the Intersection tool will throw in the alignment as an elevation target instead of the bad profile. If you find that to be the case, remove the alignment from the list.

    The Select a region to edit: prompt should still be active.

34. Select the RG - Full Section region in the south part of the intersection along ROAD B, as indicated by Figure 10.36.

    

35. Repeat steps 28–30.
36. Press ↵ to end the command.

    Now if you were to clear the events out of Event Viewer and rebuild the corridor, you would receive no errors. It's better to reserve the error list for those items that you need to address.

The files 1005_ManualIntersection_FINISHED.dwg and 1005_ManualIntersection_METRIC_FINISHED.dwg are available for your review.

Troubleshooting Your Intersection

The best way to learn how to build advanced corridor components is to go ahead and build them, make mistakes, and try again. This section provides some guidelines on how to “read” your intersection to identify what steps you may have missed.

1. Your lanes appear to be backward. Occasionally, you may find that your lanes wind up on the wrong side of the EOP alignment, as in Figure 10.37. The most common cause is that your assembly is backward from what is needed based on your alignment direction.

   

   Fix this problem by editing your subassembly to swap the lane to the other side of the assembly. If the assembly is used in another region that is correct, just make a new assembly that is the mirror image of the other assembly and apply the new one to the alignment.

   Since so many design elements rely on the alignment as their base, it is better to add a new assembly rather than reversing the direction of the alignment.

2. Your intersection drops down to zero A common problem when modeling corridors is the cliff effect, where a portion of your corridor drops down to zero. You probably won't notice in plan view, but if you rotate your corridor in 3D using Object Viewer (see Figure 10.38), you'll see the problem. The most common cause for this phenomenon is incorrect region stationing.

   

   Fix this problem by making sure your baseline profile exists where you need it, and make note of the station range. Set your station range in the corridor to be within the correct range.

3. Your lanes extend too far in some directions. There are several variations on this problem, but they all appear similar to Figure 10.39. All or some of your lanes extend too far down a target alignment, or they may cross one another, and so on.

   

4. This occurs when a target alignment and profile have been omitted for one or more regions. In the case of Figure 10.39, the EOP Left baseline region was set to only one alignment. In an intersection, you need two targets in a corner region to model the road correctly. You would see a similar issue appear if the Selection Choice If Multiple Targets Are Found option were set to Target Farthest From Offset.
5. Your lanes don't extend far enough. If your intersection or portions of your intersection look like Figure 10.40, you neglected to set the correct target alignment and profile.

   

6. You can fix this problem by opening the Target Mapping dialog for the appropriate regions and double-checking that you assigned targets to the right subassembly. It's also common to accidentally set the target for the wrong subassembly if you use Map All Targets or if you have poor naming conventions for your subassemblies.

Finishing Off Your Corridor

Now it's time for you to fill in another kind of gap in the corridor. You will be filling in the corridor between the intersections you created.

1. Open the 1005_ManualIntersection_FINISHED.dwg (1005_ManualIntersection_METRIC_FINISHED.dwg) file, which you can download from this book's web page.
2. On Prospector, expand the Intersections branch.
3. Zoom into the ROAD A-ROAD E intersection and select it to reveal its grips.
4. Grab the leftmost diamond shape region grip, which coincides with ROAD A alignment, and drag it over to the adjacent diamond shape region grip in the ROAD A-ROAD E intersection, as shown in Figure 10.41.

   

5. Notice how your intersections become out of date according to the yellow alert shield that appears next to each.
6. Right-click ROAD A-ROAD E and select Update Regions And Rebuild Corridor.
7. When the Intersections - Update Corridor Regions dialog opens, select Continue With Update.
8. Notice how the stretched region returns to its original position.
9. This could be a problem if you are relying on the dynamic dependencies of your intersections to keep your corridor updated. Next, you'll try an alternative method of filling in the gaps.
10. Select the corridor, and on the contextual ribbon select Add Baseline from the Modify Corridor panel and do the following:
    1. In the Create Corridor Baseline dialog, choose ROAD A as the Horizontal Alignment. Alternatively, you can use the green select object button in the dialog. Click OK to continue.
    2. In the Select A Profile dialog, select FG-ROAD A. Click OK to continue.
11. On the contextual ribbon, select Add Regions from the Modify Regions panel, and do the following:
    1. At the Select a baseline: prompt, place your cursor over the ROAD A alignment and left-click.

       The Select A Baseline dialog opens. The command ascertains that there are four baselines associated with ROAD A. The first three on the list belong to the three intersections on ROAD A.

    2. Select the last baseline on the list and click OK.
    3. At the Specify region start station prompt, snap to the diamond grip, as shown in Figure 10.42.

       

       When selecting the region start station, it must be an earlier station than the region end station that you will select next.

    4. At the Specify region end station prompt, snap to the diamond grip, as shown in Figure 10.43.

       

    5. In the Create Corridor Region dialog, select the Full Section assembly and click OK to apply.
    6. In the Target Mapping dialog, in the Object Name column next to Surfaces, click <Click Here To Set All> and then select Existing Surface.
    7. Click OK to continue.
    8. Click OK to close the Target Mapping dialog.

       Your new baseline-region should resemble Figure 10.44.

       

       The Add Region command is still active.

    9. Repeat steps 9c–9h for the rest of the empty regions along ROAD A.
    10. When the regions along ROAD A are complete, press ↵ to end the Add Regions command.

Optionally, you may repeat steps 8–9 to fill in the gaps in this corridor along the remaining areas of ROADs B, C, and D.

The files 1006_FillingCorridorGaps_FINISHED.dwg and 1006_FillingCorrodorGaps_METRIC_FINISHED.dwg are available for your review.

Using Corridor Utilities in Practice

There are many uses for the utilities outlined in this section. Once you get the hang of using some of the corridor utilities, you should find that they are straightforward. In the exercise that follows, you will dabble in the corridor utilities:

1. Open the file 1008_CorrUtils.dwg (1008_CorrUtils_METRIC.dwg).
2. Select the corridor by clicking one of the frequency lines (these are the magenta lines that are perpendicular to the alignment).
3. From the Corridor contextual tab Launch Pad panel, click Feature Lines From Corridor.
4. At the Select a Corridor Feature Line: prompt, click the south daylight line (this will be the line that is not a constant offset from the centerline alignment).

   The Select A Feature Line dialog will appear if you click the daylight line in a cut or fill region. This is because Civil 3D makes two distinct feature lines in these areas. Recall from Chapter 9 that feature lines are formed as a result of marker points with the same name in the assembly connecting together at frequency stations. In other words, why do you have two feature lines here? Because the daylight subassembly creates two marker points at the catch point.

   You want the Daylight feature line because it is continuous through the length of the corridor. Daylight_Cut appears only in the cut areas (red) and Daylight_Fill appears only in the fill areas (green). Where the corridor transitions from cut to fill (or fill to cut), you will see a yellow line. Only the Daylight feature line will appear in the transition regions.

5. If needed, highlight Daylight and click OK.
6. In the Create Feature Line From Corridor dialog (Figure 10.55), clear the check box labeled Create Dynamic Link To The Corridor.

   

7. Leave all other options at their defaults and click OK.
8. You should still be in the Create Feature Line From Corridor command and the command line should return to the Select a Corridor Feature Line: prompt. If you accidentally exited the Feature Lines From Corridor command, start it again from the Launch Pad panel. Click the daylight line on the north side of the road.
9. Repeat steps 5–7 to create a second feature line out of the north daylight feature line.
10. Press Esc to end the command.
11. Select the corridor again if it is not already selected.
12. From the Corridor contextual tab Launch Pad panel flyout, click Points From Corridor.
13. In the Create COGO Points dialog, do the following:
    1. Toggle on the option For Entire Corridor Range.
    2. Name the new point group Corridor Stakeout.
    3. In the Select column, clear all the check boxes except Daylight and ETW, as shown in Figure 10.56. (Hint: Press the Shift key as you click to unselect multiple items at once.)

       

    4. Click OK.
14. Save and close the drawing.

Completed versions of this exercise are available with the rest of the dataset.

Drainage First

Based on your existing ground surface, determine the general direction that you want water to flow away from the center of the roundabout. Use grading tools and a feature line to create the general drainage direction of the roundabout.

Chapter 14 will go into much more depth on creating grading. You will certainly want to have an understanding of grading basics before you tackle a roundabout.

Create a feature line that represents the highest elevations. In the example shown in Figure 10.59, the feature line slopes downward and acts as a ridge to separate water flow. The grading tools are then used to create grading objects and a corresponding surface model called Roundabout Grading.

The Roundabout Grading surface will be the basis for your profile elevations through the rest of the design process.

Roundabout Alignments

Roundabouts need alignments to guide the design for the same reasons that an intersection needs them. Alignments will be baselines and targets for the approaches and rotary. Create alignments manually with the tools you learned to use earlier in this chapter, or start with the handy roundabout layout tool.

The roundabout layout tool creates horizontal data based on the location of the center of the roundabout and the approach alignments.

In the exercise that follows, you will create the Civil 3D alignments needed to create a roundabout:

1. Open the 1011_RoundaboutLayout.dwg (1011_RoundaboutLayout_METRIC.dwg) file, which you can download from this book's web page.
2. From the Home tab Create Design panel, select Intersections Create Roundabout, as shown in Figure 10.60.

   

3. At the Specify roundabout center point: prompt, use your Intersection Osnap to select the point where the alignments intersect.

   The alignments leading into the roundabout are often referred to as approaches.

4. At the Select approach road: prompt, select all four alignments leading into the roundabout, and press ↵ when you have finished.

   You now see the Create Roundabout – Circulatory Road page of the wizard, shown in Figure 10.61.

   

5. Verify that you are using the correct standards for your units. Click the ellipsis next to the Roundabout Design Standard File field, and verify that you are using the correct XML standards file. Imperial users should be using Autodesk Civil 3D Imperial Roundabouts Presets.xml. Metric users should be using Autodesk Civil 3D Metric Roundabouts Presets.xml.
   1. If Roundabout Design Standard File is set correctly, click Cancel and continue to step 6.
   2. If it is not set correctly, browse to the C:ProgramDataAutodeskC3D 2015enuDataCorridor Design Standards folder. Browse to either the Imperial or Metric units folder and select the correct roundabout presets XML file. Click Open to return to the Create Roundabout dialog.
6. From the Predefined Parameters To Import drop-down, choose R = 75 (Rg = 25m).

   This will be the radius from the center of the roundabout to the outermost circular edge of pavement. This will also adjust other settings in the dialog.

7. Set Alignment Layer to C-ROAD and Alignment Label Set to Major And Minor Only. Click Next.

   Now, you'll design the approach road exit and entry geometry. The options in the Create Roundabout – Approach Roads page of the wizard (see Figure 10.62) can be set independently for each approach, or you can click Apply To All, which will set the geometry for all four approaches.

   

8. On the Create Roundabout – Approach Road page, do the following:
   1. Set Predefined Parameters To Import to R = 75 (Rg = 25m).
   2. Change the alignment layer to C-ROAD. Hint: You can type in the layer name or pick it from the drop-down.
   3. For Alignment Label Set, choose Major And Minor Only.
   4. Leave all other settings at their defaults.
   5. Click the Apply To All button, and click Next.
9. In the Create Roundabout – Islands screen (see Figure 10.63), again set Predefined Parameters To Import to R = 75 (Rg = 25m).

   

10. Click Apply To All, and then click Next.

    The final screen of the Create Roundabout Wizard deals with pavement markings and signage. Notice that you can specify your own blocks for the signs that will be placed in this process.

    Everything created in this last step is an AutoCAD polyline or block. The polylines have a global width set to indicate pavement marking thicknesses. These thicknesses are set in the Markings And Signs page (Figure 10.64).

    

11. Leave all defaults in the Create Roundabout – Markings And Signs page (Figure 10.64), and click Finish.

    Your roundabout should resemble Figure 10.65. Since standards vary by region, the metric drawing will have slightly different default pavement markings.

    

    Finally, you will add a turn lane in the NW quadrant of the roundabout. When you're creating slip turn lanes, remember that the turn radius must be large enough to fillet the exit and entry roads without overlapping the other alignments.

    When selecting the approach entry and exit alignments, you need to click the shorter approach alignments created by Civil 3D rather than the original approach road. For this reason, the exercise has you select inside the islands, just to be sure.

12. From the Home tab Create Design panel, select Intersections Add Turn Slip Lane.
13. When prompted to select the entry approach, select the north approach alignment inside the curb island.
14. When prompted for the exit approach, select the west approach alignment inside the curb island, as shown in Figure 10.66.

    

15. In the Draw Slip Lane dialog shown in Figure 10.67, set the lane width to 14′ (4 m) and the radius to 150′ (45 m).

    

16. For Alignment Layer, choose C-ROAD, and for Alignment Label Set, choose Major And Minor Only. Click OK.

    Your roundabout will now look like Figure 10.68.

    

17. Save and close the drawing.

The completed files, 1011_RoundaboutLayout_FINISHED.dwg and 1011_RoundaboutLayout_METRIC_FINISHED.dwg, are available for your review if desired.

You now have all the alignments you need to start your roundabout design. At this point, you can add geometry to the alignments and modify what Civil 3D has created for you.

The horizontal layout is complete, but the roundabout design is far from done. No vertical data has been created; that is up to you.

This is as far as we will take you in this book in regard to building a roundabout step by tedious step. Rest assured, however, that if you have truly mastered corridors, the technique for completing a roundabout is similar to that used for any intersection.

The remainder of this chapter gives you an overview of how to accomplish the rest on your own.

Center Design

All profiles need to meet at the elevations inside the traveled way in the circular pavement area of the roundabout. Therefore, the main circle design comes first.

To see an example of a completed roundabout corridor, open the drawing 1011_RoundaboutExample_FINISHED.dwg or 1011_RoundaboutExample_METRIC_FINISHED.dwg. Use these examples as a guide to “reverse engineer” your own roundabouts when you've mastered other forms of intersections.

You can use any of the circular alignments created by Civil 3D as the basis for this step, as long as your assembly works with the design. Remember to make note of which direction the alignment goes, to ensure that the assembly you create is not backward.

Extract profiles for the main circle design from the Existing Intersection and Roundabout Grading surfaces, as shown in Figure 10.69.

The assembly you create for this preliminary design will also be used in the main design. Decide which alignment will be used as the circular design basis, and create an assembly based on your alignment location and desired geometry, as shown in Figure 10.70.

This assembly can be used in several steps of the process. First, it is used in a preliminary corridor called RAB MAIN. It can also be recycled to be the centerpiece of your main corridor. In the example, the main circle alignment created by Civil 3D, Roundabout_OUTER_EDGE, was used as the baseline for this initial corridor. There are no targets or frequencies set in this corridor. Like the cul-de-sac example earlier in this chapter, this is a preliminary corridor, used to ensure that profiles from the approach roads tie in at the correct elevations.

In the example drawings, a Top link surface was created from the RAB MAIN corridor. At this point, the roundabout will resemble Figure 10.71.

Profiles for All

You have all the preliminary surfaces in place, and you have all the alignments you need, so it is time to extract profiles from your various surfaces.

In the 1011_RoundaboutExample_FINISHED.dwg and 1011_RoundaboutExample_METRIC_FINISHED.dwg files, the surface profiles for all the approach alignments were created by sampling the existing ground, drainage surface, and preliminary RAB MAIN corridor surface. These profiles will look something like Figure 10.72.

When you create your design, you will see all your design considerations in the profile views. No matter how you decide to tie into existing ground and slope upward toward the surface, your design must tie into the preliminary center surface, as shown in Figure 10.73.

Use techniques you learned earlier in this chapter to assist you. Labels are an especially valuable tool for roundabouts. Keep your profile views organized because you will have at least three for each approach. If you have a slip turn lane, you will have a profile for that as well.

Tie It All Together

Stretch your legs and go for more coffee. It is time to put this thing together into a completed corridor. When you model the corridor initially, ignore curb islands—you will add them as individual corridors in a later step.

A simple roundabout can be completed using as few as three assemblies. In our example, however, the slip turn lane necessitates a total of four assemblies. In addition to the RAB Main assembly you saw in Figure 10.70, you will need three more assemblies, as shown in Figure 10.74.

These assemblies will be tied to the EOP alignments and profiles as baselines, similar to a traditional intersection. Each quadrant of the roundabout will target at least two alignments and profiles, as shown in Figure 10.75.

Keep in mind the direction of your alignments. If you build the corridor in stages, check the corridor periodically to make sure it is building correctly.

Create a corridor surface from your completed roundabout lanes. You will likely have to use the Add Interactively tool to add the boundary correctly.

Finishing Touches

The median islands are the last parts to go on the corridor. You can create them using simple grading objects, but since this is a book about mastering skills, and this is a chapter about corridors, you should examine the dynamic way.

Create a simple assembly containing the curb and gutter for the curb islands. This will be the assembly that you use with the median corridors (Figure 10.76).

Each median island will need its own alignment. Take note of the direction of the alignments to make sure they are compatible with the curb island assembly. If necessary, change the direction of the alignments using the Reverse Direction tool in the Modify panel of the contextual ribbon tab. Figure 10.77 shows the bypass island and north island with directions.

The good news is that the elevation data for the medians is already complete. Your main corridor's surface will act as the profile for each individual median. This also means that once the curb return corridors are created, they will be dynamic to the main corridor. After these little corridors are created and surface model information has been obtained, you can set them to Rebuild – Automatic and forget all about them.

Extract a profile for all the curb return alignments from the Top link surface model from the main roundabout corridor, as shown in Figure 10.78. You do not need to see this profile in a view, so you can click OK to extract.

When the design roundabout corridors are complete and surfaces are made, the next step is to merge the surfaces. Create a final surface model and paste the main roundabout design in first. After the main corridor is pasted in, paste the smaller median corridor surfaces, as shown in Figure 10.79. The center median is already taken care of by the first baseline.

Your next step is to use the corridor fine-tuning techniques you learned earlier in this chapter to ensure that your grades are correct and the design is correct. To see an example of a completed corridor using these steps, take a look at 1011_RoundaboutExample_FINISHED.dwg (1011_RoundaboutExample_FINISHED_METRIC.dwg), which you can download from this book's web page.