The optional codes associated with a subassembly point, link, or shape components determine some of the behavior you will see in corridor modeling.
Codes allow you to apply simple or complex rules governing the offset and elevation behavior of subassemblies. You can choose to add codes to certain subassembly components to implement presentation or annotation features to a corridor design.
A typical subassembly is comprised of the following components, which can have codes associated with them:
For a set of point, link or shape components, you can define a set of display characteristics and assign them to a code set style. You can then assign a code set style to a subassembly, assembly, corridor, or section view.
You can assign appropriate label styles to various code sets in the code set styles.
When designing custom subassemblies, you must consider not only the geometric shape of the corridor model that will ultimately be created by the subassemblies, but also how the model is used for post-modeling design operations. These operations include:
Nearly all of these operations depend on the codes assigned to points, links, and shapes in the corridor model. To create models that integrate into all of the operations listed above, the coding scheme must be carefully designed before creating the first subassembly. The best practice is to diagram all of the different roadway types and situations that can be anticipated for the users you are supporting. Next, devise and annotate codes for all critical points, links, and shapes. Use this diagram when documenting the codes for each subassembly. Note that it is difficult to design a single set of codes that meet needs of every operation. For this reason, AutoCAD Civil 3D lets you assign any number of codes to each point, link, and shape. How these codes are utilized is described in the following sections.
You can create new point, link, and shape codes using a .NET language.
For more information about creating point, link, and shape codes using .NET languages, see AutoCAD Civil 3D Developer’s Guide.
Point codes are the feature codes assigned to the endpoints of the links that make up the subassembly component
| Operation | Description |
|---|---|
| Corridor Modeling | The corridor model is represented graphically by roadway cross sections at predetermined stations, with longitudinal strings connecting points between adjacent stations. Points with the same code and in the same region of the section are automatically connected with longitudinal lines. |
| Plans Production | Many organizations require that critical points be annotated on cross section drawings. For example, a given state’s Department of Transportation may require the following: 1.) Elevations at ditch bottoms, 2.) Slopes (x:1) of ditch sides, clear zones, and cut/fill daylight links, 3.) % Slopes of lanes and shoulders, 4.) Offsets of the cut/fill daylight points. To create custom cross-section sheet utilities that meet these requirements, these points must be identifiable within the model. Another plans production operation is depicting the limits-of-construction in plan view, with different symbology and line types used for cut lines and fill lines. |
| Design Surface Modeling and Staged Design | Point codes make it possible to extract finish grade profiles at critical points on the corridor model surfaces. For example, a profile connecting the left edge-of-pavement points of a roadway can be used in drainage analysis and design, tying links from an adjacent road’s model, and to combine corridor models with grading models. |
| Right-of-Way Analysis | The limits-of-construction of the corridor model can be determined by extracting alignments or figures that connect the cut/fill daylight points on each side of the model. These are used to determine what property has to be acquired. |
| Slopestake reporting and construction stakeout | Identifying critical points on the different layers of the corridor model is essential to creating construction staking reports, or when exporting data to survey data recorders for construction stakeout. Since grading is nearly always done to the subbase line, not to the finish grade, it may be necessary to define distinct codes on both the finish grade and subbase surface links. For example, the edge-of-traveled-way may use code ETW on finish grade, and ETW_Sub on the subbase layer. |
The cut/fill daylight points are a good example of where two codes may be needed for the same point. If the daylight points for both cut and fill links have the code “Daylight”, then it is easy to depict and extract a single figure defining the limit of construction on each side. If the same points have the code “Daylight_Cut” or “Daylight_Fill,” depending on circumstances, it is also easy to annotate cut and fill daylight lines differently.
Link codes are the feature codes assigned to each of the links that make up the roadway component. A link is defined as a single straight-line segment between endpoints.
| Operation | Description |
|---|---|
| Design surface modeling | Design surfaces can be built by extracting all links with a particular code. Link codes should be designed so that it is easy to extract the types of surfaces needed for surface modeling. Typically these are used for earthwork calculations, additional grading, visualization, and drainage analysis. Depending on the application, you may need to extract paved surfaces, all finish grade surfaces, or subbase surfaces. |
| Earthwork and material volume analysis | Different layers of the corridor model can be separated and used for volume calculations using tables that define materials in terms of which link codes are above, below, left, and right of the material layers. Simple cut and fill quantities are usually determined by comparing the existing ground to a combination of unpaved finish grade links and subbase links. Pavement layers, such as wearing course, asphalt base, and granular subbase, are determined based on the surface links defining those as closed areas. |
| Visualization and rendering | For realistic renderings of design surfaces, it is useful to distinguish between different surface materials such as pavement, gravel, grass, and concrete. |
To meet the requirements of these operations, it is usually necessary to assign multiple codes to links on certain portions of the roadway. A typical scheme:
| Link Code | Description |
|---|---|
| Top | Assigned to all links on the finished grade, whether paved or unpaved |
| Pave | A second code assigned to all paved links on the finished grade |
| Datum | Assigned to all unpaved finished grade links, and all links on the bottoms and sides of the subbase layers |
| Subbase | Assigned to all links on the bottoms and sides of the subbase layers |
Thus, the Top links can be used to build a surface model of the entire finished grade surface, which is used for visualization and drainage analysis. The Pave links can be used to render the paved portions of the finished grade surface with a particular color or texture. The Datum links can be used to model the surface that is graded with earth moving equipment, and is also used for simple cut and fill volume analysis. The Subbase links are used to define the bottom of the granular base material areas for material volume analysis.
Shapes are closed cross-sectional areas created by a single subassembly. The primary use for shape codes; defining hatch patterns for different materials, and to extract areas for material volume tabulation. The codes should reflect how you want the materials identified in the earthwork reports.