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Inside Autodesk Civil 3D there are intimate, hierarchical relationships between an Alignment, its child Profiles, child Offset Alignments, their slope-controlled Profiles, Curb Return Alignments and their Connected Alignment and Profile cousins, and Intersections. Sooner or later, we discover that the many design control Civil 3D Features all at work together and in concert within the context of the Civil 3D Corridor model.

The many Alignment-based Civil 3D Features are at the heart of the practical world of our managed design relationships in our production Civil 3D project structures.

Yeah. We know. Surfaces and Gradings are mission critical to civil engineered projects too. We already talked about that in the Civil 3D Alignment post. In short – How we manage the design control in Civil 3D often matters a great deal in the time frame and workflows of a production project.

The Civil 3D Alignment is a Design Control Manager

The Baseline for Design Development in Civil 3D

“Did you say Intersections?”
Maybe you were taught that a Corridor is a single Baseline (one Alignment and Profile pair) in a single Region (a single Assembly)? The singleton Corridor with this form of minimalist design control is a training and demo exception and not the rule of thumb for most of our common design problems in Civil 3D Land.
We explored some of that design optionality in the recent Cook with Civil 3D Corridors post.

If we pay attention to the development of Civil 3D software tools, one critical path remains. We should…

Follow the Money

What tools has Autodesk invested in and delivered? We may not appreciate that Autodesk focused on software feature and benefits we do not initially consider to be the most important things to our civil engineering design practice.

Focus on What Matters

The Autodesk Alignment and Corridor model focus is not centered around our historic CAD workflows either.

We can lose sight of the fact that while better models can produce better pictures and publications that does not mean that pretty pictures will produce better models.

Does Civil 3D provide us a new and different ways to solve classic civil design problems? You bet.

The Many Alignment Design Control Manager Roles

In the earlier An Alignment in Civil 3D post, we proposed a mental rename of Alignment to the Design Control Manager. We reviewed the ever-growing, big list of the many Alignment Design Control Managers.

  • Horizontal Control Manager
  • Vertical Control Manager
  • Offset Control Manager
  • Site Parcel Manager
  • Superelevation Control Manager
  • The Corridor Engine Manager
  • The Feature Line Manager
  • Pipe and Pressure Pipes Manager
  • Plan Production Tool Manager
  • The Civil 3D Annotation Manager

The Feature Line Manager emerged, or at least became more operational, when shared DREF Corridors arrived in Civil 3D. Feature Line management is what Sets of managed Codes in Corridor Code Set Styles and the related managed Feature Lines are all about. If that reference to Codes is a mystery to you, it worth serious consideration and study.

It seems obvious that managed collections of project-based, shared Feature Lines are a more productive design approach than individual Feature Lines siloed in individual design drawings.

The tricky bit is to learn when, where, and how to accomplish that fact.

Alignment Design Control Manager Futures

We might toss in a potential new Alignment role as a Grading Optimization (GO) Manager too. That role in the AEC Collection GO product might take a bit to get our heads around. This perspective may seem counter intuitive given that GO Zone definitions are polygon primitive based.

We must ask, where and how do we develop, store, and manage our project-based, shared Zones and other significant linear GO definitions? In any case, GO implementation in our projects will require new structures in our Civil 3D Project Templates.

That makes eleven (11) Design Control Manager roles plus one as the Civil 3D Baselines Manager.

It’s all about the Baselines, Baby.

The Dirty Dozen?

Whoa. You must be kidding?

How is an Alignment like a 60’s movie about bunch of action hero actors cast as real bad dudes and sent on an impossible mission?

What we tend to believe is disposable, often seems to decide to argue the point.

A Fundamental Civil 3D Baseline

What is easiest to share in the Civil 3D project context can often be more significant than what Civil 3D Features and AutoCAD primitives are easiest create or to convert in Civil 3D.

The circular and iterative workflows that engineering design in Civil 3D favors and requires often suggest that we may want to favor the shared data behind over the CAD lust of quicker creation and conversion tools.

The When and Where can be more efficient for our work than the What and How.

Larger Perspectives

The not-so-small change of What can become a Baseline perspective allows us to improve our production skills and use of the Civil 3D Alignment-based tools.
In an infamous Cook with Civil 3D Corridors post I state the Corridor engine is the Design Manager in Civil 3D. How we think about what a Corridor can do makes all the difference.

Primary Design Relationships

The Alignment lets us set up the Design Control via its many Design Control Manager roles.
We must ask and identify:
How many of those roles can manage a Baseline?

The Corridor Feature allows us to manage the resultant design(s) constructed from all those managed details.
See the classic videos about Linear and Non-linear Corridors on the Framework Previews page.
The Site Grading with Corridors page videos covers these topics in deeper detail.

The thoughtful use of the Intersection Wizard, Offset Alignments and their children, Connected Alignments, and Civil 3D Data References (DREFs) helps us reduce the repetitive setup and management of all that interrelated work.

Aren’t our Parcels, easements, and other resolved areas also related to the right of way?
These issues are not confined to roadway or other linear design problems but to site design as well.

The project-based, shared context, the storage structures, and workflow patterns matter in Civil 3D.

Those multiple relationships get complex with more to manage.

Alignments Become Baselines?

Is an Alignment a Corridor Baseline? No.
God knows, we are almost tempted to answer, yes.

Must the Corridor Baseline control be an Alignment? No. Yes. Errr. Wait a minute.
A Baseline definition is an Alignment and Profile pair isn’t it? Oh yeah.

A Feature Line employed as a Baseline behaves almost the same as an Alignment and Profile pair.
The difference between the two is a vital and sometimes critical path Separations of Powers issue.
Let’s hope that point is not lost on the unwary.

We’re not mincing words or semantics here.
Corridor Baselines are not Alignments or they could be called that.
Feature Lines are not Baselines or they could be called that.

Better Managed Design

What is Corridor Baseline there for?

A Baseline is the primary Station-based design management control device inside a Corridor Feature.
It is way too easy to miss the more important point that a Baseline collects the key geometry points and the managed segments relationships.

What is Corridor Region there for?

There is a quick and dirty answer. We need to scratch our heads and seriously mull over the obvious cross section control answer.

Sometimes basic Civil 3D How to instructions, tutorials, and videos disguise, and/or even confuse, the ever-evolving design with Corridors realities.

Kinds of Civil 3D Baselines?

Note that the Civil 3D help files specifically state distinctions between Corridor Baselines, Horizontal Baselines, and Vertical Baselines. Seriously? Kinds of Civil 3D Baselines?

These are context sensitive definitions of the word Baseline.
The Corridor engine does us allows us to include separate and distinct horizontal and vertical control definitions for Targets from many Civil 3D Features and, kindly, even AutoCAD primitives as well.

The State of the Managed Civil 3D Dynamic Model

Alignment and Profile pair Baselines remain the primary method we can employ and manage to build and share design control across many project drawings in Civil 3D.

The Civil 3D Baseline distinctions and the inherent Horizontal and Vertical Control duality is important to the functionality and performance of the Civil 3D Corridor engine.

These days most end-product Corridors are multi-Baseline and/or multiple Region constructions.
Perhaps a separate rough subgrade Surface solution and a separate finished top grading Surface solution clarify the minimum of what exactly we mean by that?

Can the same Alignment provide Horizontal Control for two separate Baselines in the same Corridor?
Of course, but that fact is not all that intuitive until we see Corridors for what they are –
Collectors and resolvers of our better-managed design control.

Corridor Design Optionality and Quality Control

Please tell me that you routinely turn on and off Baselines and/or Regions in your Corridors?
Aside from the obvious performance benefits there are important reasons to employ all those Baseline and Region on and off checkboxes in the Parameters tab of the Corridor Properties dialog box.

The State of Our Civil 3D Design

The Baseline - We must learn to employ all the many Civil 3D tools to manage the State of our Civil 3D Design.

How else do we learn to manage our Corridor design Optionality, improve our heuristics, and simultaneously manage the design quality control?

How Many Baselines Do We Need?

The simple answer is “One.” 

The more competent chuckle and say, “As many as we need.”

The Baseline to Make Civil 3D Work
Get the Framework for Civil 3D Release 8


Book of Alignments Posts

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