Defining basic features in Civil3d

Points
Points are the basic building blocks in AutoCAD Civil 3D. In civil engineering projects, points are used to identify the existing ground locations and design elements. In Civil 3D, each point has a unique number and each numbered point has properties that include information such as northing, easting, level, and description. These points can also have additional properties to control their appearance, such as point style, point label style, and layer.

Surfaces
Surfaces are key objects in AutoCAD Civil 3D and these are a three-dimensional geometric representation of the surface of an area of land. In Civil 3D, surfaces can be composite or volumetric that represents the difference between two surface areas, as in case of volume surfaces.

The surfaces are created using points, point files, DEM data, existing AutoCAD objects, contours, breaklines, and boundaries. You can also import the information regarding the surfaces from LandXML, TIN (Triangulated Irregular Network), and DEM (Digital Elevation Model) files.

In AutoCAD Civil 3D, you can perform various surface analyses to show different height ranges, slopes, and watershed areas. This is done to ensure that there is no unwanted points in the design.

Alignments
In a civil engineering project, an alignment object represents centerlines, carriageways, verges, highway boundaries, or construction baselines. To create and define the horizontal alignment is the first step in highway, railway, or site design process.

In AutoCAD Civil 3D, an alignment object can be drawn from a polyline or it can be created using the Alignment Layout Tools toolbar. The alignment objects can also be edited using the grips or commands in the Alignment Layout Tools toolbar.

Gradings
In AutoCAD Civil 3D, the grading tools and commands enable the engineers to grade a surface by applying different criteria, such as applying slope to a surface or grade to a distance. You can then analyze the gradings and balance the cut and fill as well as volumes of a surface.

Profiles
In AutoCAD Civil 3D, profiles (or long sections) are used to show surface levels along a horizontal alignment and selected surfaces. After you create a profile you can design the vertical alignment directly on it by using standard alignment tools, grips, or editors.

Sections
In AutoCAD Civil 3D, sections or cross-sections, provide a view of the terrain that is cut at an angle across a linear feature, such as a proposed road. The sections are cut across the horizontal alignments in specified station intervals. These sections can be plotted individually for a specified station or as a group for a specified range of stations, depending on the purpose of a plot. You can generate the section volumes from a design, for both earthworks and materials, using the Quantity Take Off tools.

Assemblies and Subassemblies
An assembly and subassembly constitutes the primary structure of an AutoCAD Civil 3D corridor model. The assembly objects contain and manage a collection of subassemblies that are used to form the primary structure of a corridor model. The subassemblies can be carriageways, kerbs, and slopes that can be added to the assembly baseline to create an assembly.

Corridors
In AutoCAD Civil 3D, a corridor model is applicable for any linear ground-based feature that brings together various objects and data including subassemblies, assemblies, alignments, surfaces, and profiles.

The corridor objects are created along one or more baselines (alignments). These are then created by placing a 2D section (assembly) at incremental locations along the baselines and by creating matching slopes that reach a surface model at each incremental location. The corridor models can be edited on the basis of sections.

Pipe Networks

You can use pipe networks to draw 2D and 3D models of utility systems such as storm sewers, wastewater sewers, and more. The pipe networks are created from design catalogs, and can be edited in plan views. You can also display the pipe network parts in profile and section views. Therefore, if there is a change made to the pipe networks in plan view, the profile and section views are dynamically updated.