topic Re: Create an intersection for a looped alignment in Civil 3D Forum

Create an intersection for a looped alignment

JimJonesPELS — Thu, 11 Nov 2021 22:59:14 GMT

See attached

Re: Create an intersection for a looped alignment

Neilw_05 — Fri, 12 Nov 2021 03:39:22 GMT

You can't create an intersection if both alignments are the same alignment as in your drawing. You are left with creating it manually unless you want to break your alignment into 2 pieces. I would go with a manual approach. It is a lot of work but you only have one intersection so not a big deal. Just know it won't be dynamic to changes to the profile so set it up in a way you can manage any changes manually (i.e. create profile views of the centerlines and curb returns so you can update them).

Re: Create an intersection for a looped alignment

JimJonesPELS — Fri, 12 Nov 2021 05:36:11 GMT

Neil,

Thank you for the prompt and detailed response. I had a hunch this was the case.

The problem is that I'm just learning C3D and my drafting skills aren't great. I could lay out the intersection with my HP 41 in a few minutes but don't really know where to begin with all this line work.

I'm not clear on how exactly to "create profile views of the centerlines and curb returns" and then update. How do you approach?

Do you just layout out lines on the 0 layer to connect in model view and then fillet around the quadrants? How does that translate to the profile? The lines created must be what - feature lines or poly lines - something like that? Any tips?

Thanks again,

Jim

Re: Create an intersection for a looped alignment

Neilw_05 — Fri, 12 Nov 2021 15:35:41 GMT

You will need to learn about alignments, profiles and intersections if you want to build a corridor. There are tutorials for all of those workflows in the help system. I suggest you spend some time there before you take on a real project. There are also YouTube videos about how to build an intersection manually. The wizard uses the same method, it just automates the process and also keeps everything synchronized when the design changes.

PS, you don't have to build a corridor. You can just use the alignments and profiles for staking if that is your objective. You can even use 2d lines and COGO points or featurelines for that.

Re: Create an intersection for a looped alignment

JimJonesPELS — Fri, 12 Nov 2021 18:05:51 GMT

Neil,

Thank you for the response.

As you can see in the drawing I have created alignments, profiles and intersection and have two corridors with an intersection. This is a "real project."

The problem is that one of the corridors closes on itself so the intersection routine won't work.

I thought I needed to build this intersection manually but don't know how to go about that. I haven't come across a wizard for manual completion of a corridor - would appreciate it if you could point it out.

If I understand your post correctly I can complete the corridor with 2D, object layer lines.

I will try that and see how it works. It seemed to me that all the lines in the corridor should have "intelligence" to determine quantities, etc.

Thanks,

Jim

Re: Create an intersection for a looped alignment

Neilw_05 — Fri, 12 Nov 2021 19:04:39 GMT

I don't know what your objective is. You mentioned being able to key the info into your calculator so I took that to imply you are only needing to stake the geometry. If you are needing to build a 3D model then you can use featurelines and gradings or a corridor. A corridor will give you a more detailed model with pavement layers, cross sections, materials quantities and more. I can't teach you how to do these things in the forum. You will need to get training or go through the tutorials and search online content. There is no easy button, sorry.

Re: Create an intersection for a looped alignment

JimJonesPELS — Fri, 12 Nov 2021 19:11:25 GMT

Neil.

I can't make the objective any clearer. See the email title.

I have gone through tutorials and am currently searching for online content.

The search continues.

Jim

Re: Create an intersection for a looped alignment

Neilw_05 — Fri, 12 Nov 2021 19:12:44 GMT

I can't make it any clearer. You will have to build the intersection manually. The wizard is of no use.

Re: Create an intersection for a looped alignment

JimJonesPELS — Fri, 12 Nov 2021 19:16:25 GMT

Right. I just need to figure out how build the intersection manually from the corridor.

That's where we started.

Re: Create an intersection for a looped alignment

Neilw_05 — Fri, 12 Nov 2021 19:17:06 GMT

Try doing this web search: civil 3d manually create intersection

Re: Create an intersection for a looped alignment

JimJonesPELS — Fri, 12 Nov 2021 19:28:14 GMT

I did. Here's what I got:

AutoCAD Create Intersection

Click the Home tab Create Design panel Intersections drop-down Create Intersection. You are prompted to pick an intersection point in the ...

The problem is that when an alignment closes on itself, there is no intersection

Re: Create an intersection for a looped alignment

JimJonesPELS — Fri, 12 Nov 2021 19:30:31 GMT

Here's another from LinkedIn:

Before you can create any intersection, first you need to have two alignments that intersect each other.

Re: Create an intersection for a looped alignment

Neilw_05 — Fri, 12 Nov 2021 19:58:07 GMT

Take a look at this. It does not use the wizard or an intersection object.

https://www.linkedin.com/pulse/how-model-intersection-manually-civil-3d-damir-pervan/

Re: Create an intersection for a looped alignment

JimJonesPELS — Fri, 12 Nov 2021 20:05:04 GMT

I did look at that earlier. I copied a sentence in my previous post from that page. You need an intersection.

I'm currently reworking by leaving the SE curve out of the interior loop to create two alignments intersecting in the NE. Once that's done I'll try to connect the two corridors through the curve.

Re: Create an intersection for a looped alignment

Neilw_05 — Fri, 12 Nov 2021 20:22:56 GMT

You don't need an intersection. All the intersection does is lock the profiles in the manual workflow. Since you can't create an intersection object your profiles will not be locked. That is why I said you will need to mange them manually. The LinkedIn tutorial explains the process you will need to follow.

Re: Create an intersection for a looped alignment

JimJonesPELS — Wed, 17 Nov 2021 20:50:18 GMT

I have determined that while an alignment can be looped - a looped corridor isn't possible. That means for a looped alignment the corridor must end short of closure at the intersection. The intersection routine is not available so the must be built manually.

Re: Create an intersection for a looped alignment

Neilw_05 — Wed, 17 Nov 2021 21:29:15 GMT

Glad you finally got it.