Cul-de-sac Design (advanced training)

The workflow below describes the situation where the cul-de-sac is modelled as part of the road corridor. The same approach can be used in the case where the cul-de-sac must be modelled as a separate corridor.

1. Create a corridor for the road where you want to create a cul-de-sac (the circle in the image below, indicates the position of the cul-de-sac):

2. Create an assembly for a dummy corridor which will be used to get the profile around the cul-de-sac. The assembly can consist of LinkWidthAndSlope subassemblies on each side. These subassemblies should use the road superelevation, each subassembly should be wider than the cul-de-sac radius (the dummy corridor must be wider than cul-de-sac):

3. Create a dummy corridor which follows the horizontal and vertical alignment of the road, use the dummy corridor for the assembly. The corridor does not need be created for the entire alignment it just needs to cover the area where the cul-de-sac is:

Dummy corridor:

Created top surface for the dummy corridor:

1. Create an alignment for the cul-de-sac (it is practical to use the Curb Return style):

2. Create this alignment as a combination of fixed and free entities:

Fixed lines:

Fixed curve:

Free curve fillets:

1. Create a profile from the dummy corridor top surface along the cul-de-sac alignment:

2. Shorten the road corridor to the point where cul-de-sac alignment connects to the road edges:

3. Create an assembly for the cul-de-sac paved area (exclude kerbs, sidewalk and cut/fill):

4. Go to the road's Corridor Properties, Parameters tab and insert a new region before/after the existing region:

5. For the Assembly select the assembly created for the cul-de-sac paved area:

6. Set the targets for the new region:

7. Use the cul-de-sac alignment as a width target for the lane subassemblies:

Corridor at the cul-de-sac:

1. Increase the Frequency for the cul-de-sac region:

The paved corridor area at the cul-de-sac:

1. Create an assembly with a kerb and cut/fill which will run along the cul-de-sac alignment (the image below shows an example with a sidewalk):

2. Go to the road's Corridor Properties and add a new baseline:

3. For a horizontal alignment use the cul-de-sac alignment:

4. For the profile select the dummy corridor top surface profile:

5. Right-click on the new baseline and add a new region:

6. For the Assembly select the assembly with the kerb and cut/fill:

7. Set the region start and end stations (the region should start and end at the points where the cul-de-sac alignment connects to the road edges):

Start Station:

End Station:

1. Increase the Frequency along the curves:

2. Set the Targets for the new region:

3. Use the NGL for target surface:

The created cul-de-sac:

Cul-de-sac contours:

1. If the contours display some discrepancies:

Shorten the corridor region for the cul-de-sac paved section slightly:

1. If it does not help, add kerb feature lines to the corridor surface definition:

The Curb 1 and Curb 2 codes are codes at the kerb edges:

Final contours:

3D view 5 times exaggerated:

1. Move the dummy corridor to the C3D-Corridor-Auxiliary layer and freeze the layer (do not delete the dummy corridor as it is used for the profile along the cul-de-sac alignment):