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The Cascaded Civil 3D Intersection

Tags intersection, corridor, alignment, horizontal control, vertical control, cross section control, video

Before Autodesk University I posted about how to Stop the Intersection Wizard to create multiple interconnected Intersections in Civil 3D. Did you miss it? Our goal there was a Complex Corridor – a related and interconnected corridor model built and managed in part by Intersections.

I like to call the Intersection the Design Control Supervisor of Civil 3D Design Control Manager – aka the Alignment. To use the Intersections Tools like this, it pays to know a few tasty bits in advance from the AutoCAD Civil 3D Book of Alignments. Register.

Get More Competent

I received a couple of interesting follow up questions to the Stop the Intersection Wizard training video.

“Doesn’t the Intersection Wizard require Profiles?”

No and yes. The recent versions of the Intersection Wizard do NOT require you to have Profiles with matching PVI points defined when you choose the initial intersection point. I demonstrated in the video that is certainly possible to move that initial intersection point around with the connected horizontal control.

What? You can do that?”

People. See the end of the recording. It’s safe. It is not a political ad. It contains no secular humanist religious propaganda either. It will not cause your iOT connected microwave or doorbell to attack the Autodesk Cloud services or Facebook’s global accounts.

Frankly, I think the Intersection needs to work from a location first and then match the Alignments PIs and match the Profile PVIs after you are done building the control. Makes sense to me.

“Won’t I need to edit the Profile geometries if I move the PIs?”

You betcha! I say that in the Stop the Intersection Wizard video.
If you do move the Intersection point, you should carefully build and/or edit the Profile geometries before you do anything vertical from the Intersection Ribbon Tools. You may need to delete any previously automatically Slope generated Profiles for Offset Alignments and/or Curb Return Alignments. Please whine and complain, but get used to that.

Intersection Properties

It is also very easy to forget you replaced a Profile but didn’t reconnect it specifically in the Intersection Properties box. (see below). This can make other related downstream choices impossible and for no apparent reason. Wizardry is often non-intuitive in Civil 3D.
You also can, and should, change the name template rules. The slope control Profile name template is found only in the Intersection command Settings. Arrrgh. Remember to clean up after yourself.

Sadly, you cannot change the Type of Intersection solution. Destroy the Intersection and build another. Yes. That means you may have Offset and Curb Return geometries to Delete. Do it first.

You can assign and/or even reassign Profiles from the Properties of an Intersection Feature.
This can sometimes come in handy to produce varied options (carefully employ the name templates and the Slope control Intersection command Settings) and/or to revise geometries after design changes.
The resultant corridor and that design control is separate from the wizard.
You can make frogs into princes.
Again I must warn you… Remember to clean up after yourself.
I know. Now I do sound like Mom.
I’ve come to hate extraneous piles of trial Offset and Curb Return geometries while I seek for solutions.
Everyone wants a delete all the Intersection connected stuff button.

Dooh. The primary and secondary slope controlled Profiles must be formally related to the Primary and Secondary Alignments employed in the Intersection. The Profile data must be present in the drawing. The Primary and Secondary Profiles need not be visible in Profile Views.

More Competent Wizardry

Someone emailed me and asked if it was possible to cascade the horizontal and vertical control of Intersections. The video clearly demonstrates exactly that. We can take things a step farther which is what he was actually after. This short video dissects such a wizardry beast.

A Cascaded Intersection

How about an Intersection driven from other parts of the horizontal control and vertical control?
What if you need an intersection driven by the Widening of another Intersection’s Curb Returns?
Say for example - a shopping center entrance.
Tell me that never happened in a shopping center project?

The not-so-basic example in the video is a drive intersection built off the flowline of a street built from another intersection. This same thing can be done from a Curb Return Baseline. Yes. There are sneaky Offsets and a thoughtful bit of Profile replacement going on. The complete corridor will produce region(s) I may or may not need.

“Wouldn’t a regular Intersection also do the same thing?”

Not exactly. Maybe I want to produce Regions only on my side of the street. Maybe I want to convert some of the regions to Overlay and Mill the “existing” street in front of my new drive.
Like that never happens.
These days in AutoCAD Civil 3D 2017 the control can even be Feature Lines from Figures or not.

You do turn on and off Baselines and/or Regions in emergent corridors all the time?

I like Intersections because I can delete Baselines and Regions and get them back on demand or move them into other corridors with Recreate Corridor Regions.

This quicky and quirky intersection sets up everything except the Assembly reassignments and target switches et al.

Master the Nasty Wizardry

The most important thing about getting this done is you have to work around the sometimes stupid user simplification methods built into the current Intersection Tools. The wizard and the Ribbon tools are built to oversimplify the selection process for a beginner or Civil 3D neophyte who walks in lock step through the wizard. If you are more skilled at intersection and corridor properties manipulations, this is really frustrating. Sorry folks. This is a skill that takes time to develop.

All the Profiles from other alignment geometries must actually be selectable from Profile Views in the drawing. Dumb. Autodesk could fix this with an All Profiles option checkbox in the Profile selection dialog boxes. They don’t listen to me. Maybe the will listen to you. Don’t hold your breath.

In certain circumstances Civil 3D will always destroy design Profiles because of bugs in the Intersection Ribbon tools. These sadly remain merely subsets of the wizard not actual separate tools. Arrgh. There are ways around this which I’ll cover in a follow up video.

Autodesk action, or lack of it, can’t stop your more competent Civil 3D skills from accomplishing wonders by innovative uses of the Civil 3D tools.

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That's innovative and definitely not dumb.

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