Better Connected Alignments in Civil 3D

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Autodesk made significant improvements in the initial release of Civil 3D 2022 to enhance Connected Alignments to better handle the complex geometries of ramps and interchanges. New horizontal Alignment Curve Group combinations were added to support combinations of spirals, curves, and reverse spirals. We can now create Connected Alignments with curves greater than 180 degrees and these geometries may also be created at relative offsets. Hoorah.

If you do this sort of roadway interchange design work, life got better in Civil 3D Land.
We must ask,
“Does the new and improved Connected Alignment help the rest of us?”

The Civil 3D Diva finds ways to make our daily production work a bit more interesting.

The Civil 3D Connected Alignments

In our recent series of posts and videos about Civil 3D Turn Lane and Median Corridors, we sort of whizzed by the detail and nuance of the Connected Alignments and Profiles that we employed in the intersection. A video review of the complicated geometries we intentionally chose to work with in this not-so-simple intersection is in order.


Median and Turn Lane Corridors in Civil 3D

Frankly, without the new Civil 3D 2022 Connected Alignment capabilities the proper resolution of all the Curb Returns would be a much more significant and time-consuming design challenge. Put another way – intersections of multiple Profile Vertical Curves do make this design solution interesting. Intersections with complex curve and spiral geometries coupled with superelevation would share a similar fate.

The new Connected Alignment capabilities provide us with new choices and approaches.

A Brief History of Connected Alignments

Connected Alignments have been around since Civil 3D 2018.1. They are technically a Curb Return Alignment type. If we perform roadway or site design with Corridors, the odds are we employ them.

The now familiar workflow scenario is to employ Connected Alignments to join separate Offset Alignments and Offset Profiles to create the familiar resolved quadrants in our Corridor intersection designs. There are similar design scenarios in site grading design.

All this Alignment and Profile based design control is Data Shortcut shareable in the Civil 3D project context. Revise the DREF design control and our Corridor design responds.

We’ll come back to the nuances of this in a second.

There must be a hundred basic How To videos of basic Connected Alignment intersection returns in Civil 3D out there. Visit our Civil Training on the Web video section for some good ones.

Feature Line Baselines

In more recent releases of Civil 3D, we can even employ Features Lines as the Corridor Baseline design control geometry sources. See Shawn Herring’s Feature Line Based Corridor Curb Returns video in Civil 3D 2019 as an example.

In Civil 3D 2022.1, all the targeting in the video becomes a lot easier and faster than that.

The Feature Line Baseline solution works. The build and edit Feature Line process is familiar to many Civil 3D folks. The Feature Line design method is relatively static. That form of design control is not currently sharable via DREFs in our project. We have fewer options, but this simple design control approach can be quicker.

Shared Design Control from Feature Lines

Yes. We can convert Corridor Feature Line based design control to Alignment and Profile shared design control. See the Site Grading with Corridors video and post series for how to do that and why.

For one the quadrants of the intersection shown in the video above, the Connected Alignment and Connected Profile design control is not connecting the Offset Alignments and their Offset Profiles.
Say What?

Let’s call this Civil 3D beasty…

The Offset Connected Alignment

We can employ the new offset capabilities of the Connected Alignment to directly connect the design control of the three main Alignments and their respective Profiles. At times this choice to employ the core geometry may be the only easily accomplished geometric resolution available to us.

In our Turn Lane Corridor example, we employ Vertical Curve geometries to demonstrate how to meet a complex Corridor design challenge. We could involve Superelevation interactions instead.

A more direct connection to the original sources may be our best bet to discover a functional solution.

In the example we employ an offset Circular Fillet of the primary horizontal design control itself and resolve the dynamic Connected Profile design.

As with all Civil 3D Alignments and their Children, the direction of the Connected Alignment is significant.

Offset Connected Alignments and Profiles from the Mains

For hopefully obvious reasons, Connected Alignment direction affects how the Assembly Subassemblies configurations to resolve in Corridor Baseline Regions. Odds are our Corridor Baseline and Region Plans in Civil 3D may require both left and right versions of the Curb Return Assemblies.

The resolution of the Connected Profile’s automatically built design control is a somewhat more nuanced. The latest version of the Connected Profile allows us improved cross slope and/or change in elevation control. The capabilities make Connected Profiles easier to build and maintain. Read the Connected Profile Tab help more than once.

DREF Offset Connected Alignment and Profile

We are able to Data Shortcut and share static or dynamic versions of the Connected Profile design control.

By default, Civil 3D 2022.1+ appears to initially make the Connect Alignment DREF Profile’s vertical design control static.
That default makes some sense.
In the project context, a static DREF makes the shared design control more stable and simpler.
Many folks may choose to edit the Connected Profile between the overlaps in any case.

Fully functional dynamic Connected Profile DREF versions appear to require that the actual Profile objects exist in Profile Views in the DREF source drawing.

We may also manually edit the Connected Profiles to make them dynamic after they are shared as Data Shortcuts. The nuance can be easy to miss.

A Word of Caution

The current build of Civil 3D 2022.1 may have issues in the Alignment Property box reporting the correct Connected Alignment details for DREF Connected Alignments if you employ the Data Shortcut Manager to replace the Connected Alignment design control in Corridor production drawings.

Know Thy Connected Design Control

None the less, Civil 3D certainly can produce stable Corridor models based on the correct Offset Connected Alignment DREF design control.

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Complex Corridor Posts