AutoCAD Civil 3D 2012 Preview: Alignment Enhancements

AutoCAD Civil 3D 2012 Preview: Alignment Enhancements

With a focus on transportation, there are quite a few enhancements for alignments in the new release of Civil 3D. This particular post is going to cover a lot of very high-level overview type information regarding alignments, and will be broken out into individual posts that will dig more deeply into the subjects over the coming month. To see what some of the new features are, follow the link!

Superelevation Enhancements

Of course superelevation enhancements are the big news here. One of the main highlights is the new axis of rotation options in superelevation. In the 2011 release of the software, the axis of rotation (or Pivot Point) was always assumed to be positioned at the centerline. However, the 2012 release expands on this and allows the following pivot cases:

• Always pivot on the road edge that is on the inside of a curve
• Always pivot on the road edge that is on the outside of a curve
• Always pivot on the left road edge
• Always pivot on the right road edge.

We have also introduce shoulder rollover control, which is specified when computing shoulder superelevation. Here, you can specify the control for shoulder superelevation on the high side and the low side of the roadway separately and specify different methods for breakover removal.

Enhanced LandXML Import of Alignment Geometry

In the past, alignments created in Civil 3D from a LandXML import have been really difficult to edit because all alignment entities were treated as fixed elements. This has caused many users to recreate the alignment after import, which was a very inefficient workflow.

New import options have been added to the LandXML Import Settings to allow alignments to maintain Fixed, Free, and Floating tangency constraints, as shown below:

The new options are as follows:

• Fixed only – this replicates the current functionality where all alignment elements are fixed.
• Floating off first element – this option assigns a fixed constraint to the first element and all subsequent elements are assigned a float constraint.
• Free and floating curve groups – this option attempts to identify supported free curve groups and floating curve groups and then assigns constraints accordingly.

Alignment Constraint Swapping

Again, in past release of Civil 3D, once horizontal alignment entities were created, there was very limited flexibility given to the user to modify the entities. Oftentimes, the user had to delete an entity and then create a new one in its place. This often led to problems, as deleting an entity largely depends on how the entity was originally created.

The goal of this functionality is to give the user more control and allow them to unlock or lock parameter constraints as well as modify the parameter constraint type of each alignment entity and relationships between horizontal alignment entities.

New Alignment Design Checks

A new criteria-based design option has been added that enables the user to specify whether tangencies between elements should be checked. This setting is enabled by default. When it is enabled, if any line, curve, or spiral element is not tangent AND connected to its previous or next element, a warning symbol will be displayed in the drawing and in the geometry editor. Obviously, a tangency check is not performed at the intersection of two line elements.

PI Index Numbering

PI (point of intersection) enhancements in Civil 3D 2012 provide a more consistent approach to the way transportation designers have traditionally defined and reported on horizontal alignment PI’s.

The concept of an implied PI is introduced with the 2012 release. This PI is solved for, but not truly defined by fixed tangents. In prior releases, only explicit PI’s could be labeled or reported on. In the transportation industry, however, there is usually no distinction between an implied and explicit PI when staking out roadway geometry in the field – both types are typically needed in plan sets.

New Alignment Labels

A new PI label style has been added to support the new explicit and implicit PI definitions. The new label style will provide the ability to label PI properties such as included angle, X-Y location, and PI index number at both explicit and implicit PI locations. This new style is meant to replace the existing Tangent Intersection label style. In legacy (pre-2012) drawings, the existing Tangent Intersection label styles are not migrated to the new PI label style.

Horizontal Geometry Band Enhancements to Profile Views

Enhancements to the profile geometry will mainly pertain to the Chinese transportation users. These enhancements include the following:

• A new component for PI which is intended to label PI properties. This component can be used to label properties of the PI independent of the curve and spiral components.
• The label properties of the curve component and the spiral component of the horizontal geometry band style have been modified to support the new PI definition of alignment.