Civil 3D Grading Multiple Baseline Mechanics

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Site Design Grading Corridors can be a practical production adventure in Autodesk Civil 3D. You could say that there are too many approaches for how to get a Site Design Grading Corridor beasty to work in Civil 3D. Sadly, there Civil 3D workflows that work for some grading design scenarios that seem to fail completely in other apparently similar scenarios. What a hassle. Why bother?

Does this mean that…

Autodesk Civil 3D Automation is Not Always Our Friend?

Tearing down a complex site grading problem into lots of individual Feature Lines and/or lots of Gradings does have some valid appeal. We know how to do Civil 3D grading by breaklines. It’s what we do.

This ostensible simplicity comes with a nasty backend. Quality control, change maintenance, and the serious annotative details produce a hefty project man-hour price tag.
Isn’t Civil 3D is supposed to fix that?

Is the brutal Site Corridor design experiential learning curve worth the effort? You betcha.
We can achieve better managed, robust, and more flexible civil engineering grading design solutions.
To be fair.
We are talking about Complex Corridors (multi-Baseline and multi-Region collections) with lots of potential moving parts and lots of distinctions in the Design Control.

The Corridor engine How to’s, When to’s, and Where to’s mechanics all become important.

Manage the Process and Complexity

In the previous posts (with videos) in this Site Design Grading Corridor series we explored the fundamentals of building dynamic, multi-planar sheet structures with the Civil 3D Corridor engine and tools. That’s not so difficult if we pay attention to what the Corridor engine needs and what it wants to eat.

Applied Frequency and Targets Matter

We discovered that our past historic experience with Feature Line grading often leads us to attempt to solve Corridor resolution problems by adding more detail in our attempt to resolve issues. Me too. We all do this. This behavior can be totally inappropriate.

The Honey Pot Lust

We could call this habitual additive lust for more detail the Corridor Honey Pot.

It might help us to remember to ask, “Who’s behind are you watching?”

The visual results out of the Corridor engine can indeed be distracting.
In Civil 3D, we need to remember to watch the data behind.
We need to keep this simple truth in mind…

By design - the Civil 3D Corridor engine creates complexity from simplicity.

Once more - let’s play with Site Design Grading Corridors…


Multi-Baseline Grading Mechanics

Complex curb, walk, and daylight resolutions are what the Corridor engine is designed to do. We either play to the strengths of the software or fight with the Civil 3D Diva tooth and nail. Clearly, we should embrace to Corridor engine tools that exist.
It’s great when most of the time this means less is more.

Autodesk introduced the initial Corridor Bow Tie Settings fix back in Civil 3D 2018+ along with Connected Alignments and that other significant Corridor improvement - Baselines based on Feature Lines. Most of those now improved upon Civil 3D Corridor engine goodies play significant roles in the Site Design Corridor mechanics covered in the video.

Connected or Disconnected Feature Lines

Automatic or connected Feature Lines inherit and maintain the Frequency settings of a parent Baseline Region. Curbs and other similar grading features often require very different Region applied Assembly Frequencies.

Very often simplified Feature Lines are exactly what works better to feed the Corridor engine for a detailed Assembly structure. Therefore, separate (disconnected Feature Lines) are sometimes the better choice for new Baselines in a multi-Baseline Site Design Corridor.

When to Region

Multi-Baseline roadway design Corridors tend to require more Regions and a Set(s) of Assemblies. Site Design Corridors often do not require as many Regions as we initially tend to assume based on previous roadway design Corridor experience.

More Regions always means more maintenance man-hours in the Corridor upkeep. Best to keep that in mind and delay Regionalizing a Site Design Baseline until it becomes the only option.

You can employ turned off Baselines and/or Regions with different Region geometries and or Assembly assignments to manage both design options and/or the current detail resolved in a Site Design Corridor.
In other words, two similar Baselines with similar Regions can be employed to resolve the separate similar Regions differently. Maybe you want to resolve and display driveways or handicap ramps or not.

Automatic Corridor Bow Settings

No one could initially say that the Automatic Corridor Bow Settings and related manual tools are all that intuitive. The software assumes that we understand that an automatic fix based on the Corridor Settings is applied to fixed width Corridor Baselines.

The Civil 3D help file still simply says “fixed width corridors” which is technically incorrect. I personally never met a Corridor Feature (which is a collection) with a width. Say saying.

Any previously manually cleared fixes (see the Clear Corridor Bow Ties tools) are remembered by the specific Baseline until you remove or replace them. As we see in the video this can be good news and bad news.

It is handy to understand and remember that redefining the Baseline geometry resets the Corridor engine automatically. Therefore, different Feature Line and/or Alignment/Profile versions of the Baseline geometries are often good to keep around.

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Grading with Site Corridors Posts

Updates, additions, and fixes to the posts in this series are on-going.