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Author: Kate Ming AutoCAD Civil 3D, AutoCAD

Ideate is dedicated to updating you on the new and improved features of Autodesk’s latest software release. In this post, I am going to discuss the new profile locking capabilities in Civil 3D.

Profile Locking Tab in Profile Properties Dialog Box

As a designer, you know that the vertical profile entities and horizontal entities are linked. Civil 3D 2015 has added functionality that allows you to determine how the vertical profile entities are linked to the horizontal entities. Specifically, you can either lock the vertical entities to specific alignment geometry points or you can lock the vertical profile entities to the alignment start. The options appear on the Profile Locking tab of the Profile Dialog box, which is shown in the image below.  


Profile Properties Box Profile Locking Tab.


Design Scenario for Comparison

To understand the two options, I am going to compare how a profile behaves for each of these options when the horizontal alignment changes. The following images set up the design scenario.


Horizontal Alignment Position before extending and moving the first tangent.


Horizontal alignment position after extending and moving the first tangent.


The original profile prior to extending and moving the horizontal tangent.

As seen in the preceding vertical profile, there is 1 PVI between the two horizontal geometry points. There is 1 PVI just after the last PI shown.  

Option 1: Anchor Profile Geometry Points to Alignment Geometry Points

In this option, the PVIs for the profile are linked to their preceding horizontal geometry point, such as the beginning of a tangent or a curve. The elevation values and distance to the preceding horizontal geometry point are the same.  This can be seen in the following image.  


Modify affected entities option. New profile after moving the horizontal tangent.

The profile begins where the horizontal alignment begins because the PVI had the same station as the beginning of the horizontal tangent. The elevation value, however, is now lower then the existing surface elevation. This is because this option holds the original PVI elevation values. The grade coming out of the first PVI is the same as it was before the change because the second PVI was along the horizontal tangent. Since the distance to the preceding horizontal PI did not change, the slope did not change either. The second horizontal tangent, however, lengthened because the third PVI is after the second horizontal curve begins. Since the distance between the first and second Horizontal PIs increased, so does the second tangent on the profile. The grade along the second profile tangent is less because the elevation values of the PVIs remain the same, but the length of the tangent increased.

That got a bit confusing, so I’ll simplify this. The PVI elevations and distance to the preceding horizontal geometry point remains the same. That is the essence of how this works.

The yellow information symbols show up along the affected profile entities. You can turn those off on the profile contextual tab, as shown below.


Profile contextual tab showing where to dismiss information symbols.

You can also choose to delete affected entities, as opposed to modifying them. This option shows up in the profile properties. This can be seen in the image below. The entities that previously were adjusted and had an information symbol on them are now deleted.


Deleted affected entities option. New profile after moving the horizontal tangent.


Option 2: Anchor Profile Geometry Points to Alignment Geometry Start

This option locks the profile to the beginning. If the beginning of the alignment changes, as it does in this example, the start of the original horizontal alignment is projected onto the updated horizontal alignment. In this case, the profile geometry – specifically the grades, curve lengths, and elevations – will remain the same after you edit the horizontal alignment while the PVI stationing will change. In the example we’ve been examining, the first horizontal tangent is being extended and moved. Unlike what the option implies, the profile does not stay tied to the alignment start, it stays tied to the projected original start of the alignment to the edited new alignment. The elevations, grades, and curve lengths remain the same, however its stationing has moved. Check out the images below.


Projected beginning of original horizontal alignment onto the new horizontal alignment.


Lock profile to horizontal alignment option after horizontal tangent has been moved.


Let me review, there are 2 options to lock a profile to an alignment.

  1. Lock the profile elevations at PVIs to horizontal PIs with the option to:
    1. Update the affected entities by locking the elevation and distance of PVIs to their preceding horizontal PIs, and,
    2. Erase the affected entities.
  2. Anchor to alignment start, which means anchor to horizontal geometry start.

Check out the video: Civil 3D 2015: Profile Locking

Thank you for reading. For more information on the software solutions, training and consulting Ideate provides, please visit the Ideate, Inc. homepage.

         Kate Ming
Kate Ming
AEC Application Specialist
Kate is a California licensed civil engineer with a BS in Civil and Environmental Engineering from UC Berkeley. Prior to Ideate, she worked at a multinational company for four years doing general civil design on large infrastructure projects. She is versed in roadway, rail, utility design and site development. She also has experience with utility demand analysis and Low Impact Development plans. As a Civil 3D Autodesk Certified Professional Kate provides training and support for Civil 3D, AutoCAD, and InfraWorks.