The Civil 3D Create Intersection Wizard can be used to quickly produce the complex corridor models, which comprise intersections, with automatically generated curb return geometry. However, this curb return geometry does not always meet design requirements. It is often necessary to use a more complex curb return profile than the single, straight grade provided by the Wizard. This is particularly true when curb returns need to accommodate drainage structures or ADA ramps, which require precise elevations at specific locations along these profiles. These requirements do not necessitate a return to manual intersection creation methods, however. Instead, the Create Intersection Wizard can be used to create the initial Intersection object, as shown in the image below.
Note: The corridor’s Code Set Style does not display the corridor section links or several feature lines. Some additional geometry and topographic elements, such as off-set alignments, have also been turned off. This is intended to reduce clutter in the images included within this article.
To prevent the Create Intersection Wizard from attempting to overwrite the modifications that will be made, we will need to delete the intersection object from the drawing. Selecting and deleting the intersection marker removes the intersection marker from the drawing area and its folder from the Prospector tab of Toolspace, as demonstrated in the images below. Note that the intersection label is also removed.
Although the intersect has been removed, the corridor regions automatically created by the Wizard remain (see image below).
A special label set with closely spaced station labels can be created and used on the curb return alignment to facilitate the location and layout of curb ramps, drainage facilities, and other design elements along the curb. The image, below, includes station labels set to a 10-foot interval for major stations and a 2-foot interval for minor stations. However, these intervals can be adjusted in the label set, as needed.
Station/offset labels can also be placed to determine precise locations of points along the curb return requiring specific elevations to be set (see image below).
Once locations are determined, a profile view can be created for the curb return profile. The automatically generated profile can be analyzed at critical points using station/elevation labels and the entire profile design can be viewed and analyzed using the Profile Geometry Editor (see image below).
It is a good idea to create a copy of the curb return profile, rather than edit the existing profile. This preserves the original design; in case it is needed for reference. Additionally, existing associations of the automatically generated profile to the intersection elements can make editing difficult, even though the intersection was deleted. The Copy Profile command is available on Profile Layout Tools (see image below).
Once the copy is created, its name and style can be edited appropriately to differentiate it from the original, as shown in the image below.
Labels can be added to facilitate design and analysis (see image below).
When you are satisfied with the design, you can reset the vertical baseline in the corridor to the new profile.
The first image, below, shows contours and spot elevations for the original curb return.
The following image shows the modified design. Note the key elevations established on the curb return and the changes evident in the contours.
This workflow can be used to modify the design of any automatically generated curb return profile, while maintaining the rest of the model developed by the Create Intersection Wizard.
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