Grading objects vs Corridors

[deltacoolguy]

Grading objects vs Corridors

I always find grading objects for edge grading to be, well, less than ideal and somewhat touchy to deal with.  They seem ok for simple stuff, but are still quirky.

I have a site in a current project where I had reason to use 5 different grading abjects around the perimeter.  All pretty simple, just grade to daylight at a specific slope.  Then I paste them all with the 'main' surface into a "composite" surface... which I D-ref out.

Then, I needed one to grade to a specific target pline on the existing surface, knowing the slope would vary.  Come to find out you cannot do that with a grading object, so I faked it with feature lines.  Then, we decided we wanted to add a ditch along that same edge.  At this point I decided to do a corridor in that section instead, and now I'm starting to wonder why use grading objects at all.

Is there a downside to using a simple corridor at the edge of a site instead of a grading object?  Seems corridors have more flexibility and are easier to manipulate, plus I can now target a horizontal pline.

What am I missing?

[AllenJessup]

I don't think you're missing anything. You described what I just went through on a site. When I needed to grade to a specific line I "faked" it with featurelines like you described. I don't think there is anything "wrong" with using a corridor. I know people who are very talented at doing that.

I will admit I'm not that familiar with grading objects. This is the first time I can remember using them in real life* since Land Desktop.

*Not in a classroom or tutorial.

[Joe-Bouza]

Note: An infill is a grading object.

[neilyj666]

You are much less likley to crash a dwg if you use corridors but there is more of an overhead in setting them up (alignment/profile etc)

I believe 2017 can use a featureline as a corridor baseline so this could be an interesting development.

[Neilw_05]

My experience in using corridors for grading exposed several problems that make them difficult to work with in grading scenarios.

As you noted in your grading scenario, we often need to transition slopes. Grading objects can do that with transitions but corridors have no equivalent. You have to manually edit the cross sections.

Varying cross slopes along linear features such as sidewalks and drive lanes requires using the superelevation tools which are rather cumbersome for such simple scenarios.

Adjusting grades requires using profiles when using corridors. You can't simply apply a relative elevation or slope between two points in plan view as we can with feature lines.

Corridors depend on alignments for the horizontal geometry. Alignments can be difficult to work with in site scenarios where you have lots of branching in the geometry. Too corridors don't handle sharp bends in the alignment very well.

Then you get into all the assemblies and regions, targeting, etc. to manage the corridors. It ends up being a lot more work and headache versus the grading tools. Unfortunatley the grading tools are problematic so there are no good solutions.

[Joe-Bouza]

Hey @Neilw_05 have tou seen this?

http://help.autodesk.com/view/CIV3D/2017/ENU/?guid=GUID-C21A3B2A-BF60-4509-A3F4-DE70312653B5

looks pretty good. something a about aut corner cleanup too but I didn;t see it in action

[Neilw_05]

This looks very promising. It addresses several of the issues I have had with the grading tools. Maybe at last we'll be able to use the product in production!

[Joe-Bouza]

That would be nice, wouldn't it?

[deltacoolguy]

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@Anonymous wrote:

My experience in using corridors for grading exposed several problems that make them difficult to work with in grading scenarios.

As you noted in your grading scenario, we often need to transition slopes. Grading objects can do that with transitions but corridors have no equivalent. You have to manually edit the cross sections.

Varying cross slopes along linear features such as sidewalks and drive lanes requires using the superelevation tools which are rather cumbersome for such simple scenarios.

Adjusting grades requires using profiles when using corridors. You can't simply apply a relative elevation or slope between two points in plan view as we can with feature lines.

Corridors depend on alignments for the horizontal geometry. Alignments can be difficult to work with in site scenarios where you have lots of branching in the geometry. Too corridors don't handle sharp bends in the alignment very well.

Then you get into all the assemblies and regions, targeting, etc. to manage the corridors. It ends up being a lot more work and headache versus the grading tools. Unfortunatley the grading tools are problematic so there are no good solutions.

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You make a lot of good points.

I have come to realize that in some aspects grading groups are better than corridors.  For example, I can adjust the elevation of a main site feature line and the grading group automatically adjusts with it.  That is very handy.

Anyway, I'm thinking I'm going to have to do a mix-and-match depending on the individual scenario.