Multiple Slope Site Corridors in Civil 3D

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Are Civil 3D Corridors employed to produce Site Design grading solutions worth the small extra efforts we need to make in our design control details? If we want more adaptive and flexible options available in our Autodesk Civil 3D site design projects, the answer is pretty obvious.

Design Beyond the Breaklines

We all know that the classic Feature Lines site design approach in Civil 3D works effectively. That solid, but individualized Feature Line approach, fundamentally lacks the easily managed collections of Feature Lines that Civil 3D Corridor Features can produce.

In the previous Civil 3D Corridor Site Design Considerations post and video, we explored the vital perpendicular particulars and nuances of a Corridor’s applied Assembly Frequency and the significance of our optional choice(s) of Target control. We learned how to quickly produce a typical planar parking lot surface and a collection of managed Feature Lines. We only scratched the surface. Eheh.

We Need Non-Linear Results

We need to couple our historic Civil 3D Feature Line create and edit skills with a newer set of complimentary Corridor skills to improve our site design project throughput and productivity in Civil 3D.

We must learn to manage our design processes, the Civil 3D workflows, and the structures of our Civil 3D project towards those more effective and productive results.

Do we recognize that the Civil 3D Corridor engine is optimized to employ Data Referenced (DREF) design control? Say what?
If we think about it, that makes sense.

Managed multiple sloped surface results and managed collections of Feature Lines are not that hard to accomplish with the Civil 3D corridor engine. We just need to know the rules of the road. There are many of them. There are important How Tos, Whens, and Wheres at play.

Let’s play…


Multiple Slope Site Design Corridors

With a single pass edit any of the many available nuances of a Corridor’s design control we can produce multiple simultaneous edits to both the multiple potential produced surface(s) results and also manage the multiple Feature Line output at the same time.

Corridor Frequencies (where the Assemblies are applied in a Region along a Baseline) are a lot more important than the typical public training demos for Civil 3D talk about.

More Assemblies in any Baseline are definitely not necessarily better. We tend to overcomplicate things too quickly – at least I do.
We all tend decrease the Frequency interval (increase their number) usually to make the Surfaces “smoother”.
Delay doing the typical Surface smoothing thing as long as possible.
We want the Corridor to resolve the way we want FIRST.

Civil 3D will resolve any Corridor better from a limited number of applied Assemblies much better and faster. We want to identify the critical geometry design points and try to only apply Assemblies at those points as much as possible.

Usually a few carefully Added Stations will help the built-in C3D Corridor corner fix it code to resolve problems better. Added Stations just before and after critical design points can also help.

Sometimes splitting Regions helps…but maybe not.

The Design Control Manager in Civil 3D

Unquestionably, Autodesk has put lots of serious and inexpensive programming effort into the Alignment Feature and it’s many related Children. Much of that code work now produces Corridors that are easier to manage with more adaptive, robust, and flexible design options.
That’s the good news.

The bad news - the resultant design control nuance is somewhat maddening and frustrating. Many CAD people just want to draw stuff and quickly connect those on-screen, visible parts together. The Civil 3D Create from Objects (Civil 3D Features from ACAD primitives) approach might work. But…

Well-constructed Civil 3D Alignment and Profile detail produces richer and more malleable forms of the Civil 3D data behind.

Civil 3D is a Diva

She does exactly what we tell her to do. She doesn’t care about your current bad camera angle, crappy set design, bad script, or your perspective on how Civil 3D things should work or behave for that matter.
She can only dutifully make you look good or downright awful.

The Civil 3D Corridor engine and tools are much more focused on the detailed and shared Civil 3D data behind. The Civil 3D Data Shortcut Manager (DSM) tools should be our familiar friend.

We must pay careful attention to the repetitive and structured processes of building up the best and most adaptive design control possible in our site design projects. We are far less likely to mess things up when the horizontal and vertical design  control is NOT in our Corridor creation drawing.

Nope. Don’t be a dope.
Civil 3D doesn’t require a project. Civil 3D is the project.

Baselines, Regions, and the Complexity Trap

How many Corridor Regions did we really need in the example single Baseline Corridor to produce the not-so-simple multi-slope surface(s) and the potential output Feature Lines?
Clearly, not as many Regions as we employ in the video.

Sometimes multiple Baselines or splitting Regions helps…but maybe not.

What is the lesson? In Civil 3D…

Always Simplify and Rename Before You Use It

The question above points to the important Corridor engine consideration that many Corridor newbie folks struggle with inside of Civil 3D.
It is way too easy to inappropriately overcomplicate a design Corridor in Civil 3D. When we focus only on a pretty of published Surface result, we often tend to fall into this trap. Just saying. Less can be more.

We usually want to focus our initial Corridor design control efforts on the mission critical and/or critical path design points and Feature Line structures we will need later in the design process.
KISS speaks volumes.

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Grading with Site Corridors Posts

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