Understanding Assemblies

Assembly objects contain and manage a collection of subassemblies that are used to form the basic structure of a 3D corridor model.

Adding one or more subassembly objects, such as travel lanes, curbs, and side slopes, to an assembly baseline creates an assembly object. This forms the design for a corridor section. The subassemblies are provided in a set of catalogs.

The following illustration shows a simple assembly object that represents one side (lane) of a two-lane road. Subassembly objects named BasicLane and BasicCurbAndGutter have been added to a baseline alignment, forming a single travel lane with a curb and gutter.

Each subassembly has a defined cross-section, and some subassemblies automatically adapt to their location. For example, the slope of a road lane changes as superelevation is applied, and a side slope automatically creates either a cut or fill slope, depending on the relative elevation of the existing surface.

The dimensions of a subassembly, such as the width of a lane or the height of a curb are stored as properties.

You can also create custom subassemblies from AutoCAD polylines. In this case, you must also specify the subassembly behavior within an assembly and in the process of corridor creation. You can define custom subassemblies and their behavior using .NET scripts, then use the AutoCAD Civil 3D COM application programming interface (API) to link these to the main application.

It is also possible to create more advanced assemblies referred to as conditional assemblies. A conditional assembly contains one or more conditional subassemblies, which apply subsequent subassemblies when specified conditions at a given station are met. For more information, see Creating Conditional Assemblies.

After creating assembly objects, you can proceed with other corridor modeling tasks, such as creating corridor objects, feature lines, and section views. For more information, see Corridors.

Review the assemblies and corridors tutorials for step-by-step instructions on how to create a variety of assemblies for corridor model.

Tutorial Exercise: Creating an Assembly

Tutorial Exercise: Creating an Assembly with a Transition Lane

Tutorial Exercise: Creating a Divided Highway Assembly

Tutorial: Creating an Assembly with Conditions

Topics in this section

• The Assembly Object

  Use an assembly object to create the structure for a corridor section.

• Assembly Settings

  Use assembly settings to control the behavior of assembly-related commands.

• Assembly Properties

  Specify administrative, and codes structural information using assembly properties.

• Assemblies Collection (Prospector Tab)

  Use the Assemblies collection in the Prospector tree to access the assemblies in a drawing. As assemblies are created, they are displayed in the Assemblies collection.

• Assembly Collection (Settings Tab)

  Use the Assembly collection in the Settings tree to manage assembly settings, styles, and command settings.