Unequal Intersections, Part 2

[deltacoolguy]

I had mentioned this in a previous thread, and got a short answer, and that did helped a great deal, but not completely.  Attached is the drawing showing the corridors and intersections.  They are rough, and the vertical aspects especially aren't complete yet, but for the moment I need to get the horizontal aspect resolved and I have read and researched and watched YouTube videos and tried everything I can imagine, but in the instances where the street widths are different on each side of the intersection will not line up properly with the curb returns.  There's a jog and the curb return itself isn't where it's supposed to be.  I have clouds drawn around the two areas in question.

I had created a corridor for the entire length of the street first, as suggested in another thread, to make sure the primary corridor itself was fine.  I was very pleased with the results of that.  Then, I broke the corridor into regions, and peeled back each region at the intersections.  Good so far.  Created the intersections as individual corridors.  The intersection where each respective side is equal width worked fine.  The other two where one street has unequal width I just cannot get to work.  Close, but not completely.

Any help and/or direction would be most helpful.

P.S.:  The drawing file is too large (2.4 MB), so I have attached a jpg showing one of the areas in question.  Both intersections are similar, so the answer should be the same for both.

[Jeff_M · Accepted solution]

To be able to post large files, check out https://www.dropbox.com/

Create the offset alignments before creating the intersection, add a widening to each of the 2 offsets. Then create the intersection. You can do it the other way around, but you will end up having to adjust the alignment lengths, curb return radii, profiles, etc.

[deltacoolguy]

I did create the offset alignments first, but I did it manually.  Meaning, I drew the offsets, widening and all, with a polyline then used "Create Alignment from Objects" and chose "Offset" as the type of alignment.  I did not use the centerline and "Create Offset Alignment".

This worked great when I drew the initial corridor, as one of the offsets is on the main road itself and the other is on one of the side streets (the image I attached).  Regardless, either way, I had the same issue with both intersections when I went to create them.

Can I presume that the manner in which I created the offset alignment made the difference?  The way I did it the offset alignments are independent entities and not tied to the centerline... or the centerline's profile.

At this point I believe I understand what you are saying and have what I need, but I'd like to finish the "process" so I can understand how and why things interacted... or didn't... the way they did.

Going forward to creating the intersection, the wizard does allow you to choose an offset alignment for each side of each road, but when I did it would never allow me to finish the intersection because I did not have have a profile for the independent offsets.  So, I went back and used the centerline, used default offsets, and so on.  This allowed me to create the intersection, but as you say, I had to then go in and adjust things, and it was just never right.

Am I correct in presuming that if I create the offset alignments using the offset feature, that it will automatically create profiles needed for me to choose the offset alignments in the intersection wizard, and will allow me to finish creating the intersection... thus saving myself a ton of tweaking?

You have been a tremendous help.  Thanks.

ETA: I will check out the drop box option.

[Neilw_05]

I may be mistaken but I beleive you need to use alignments created by the offset alignment tool. The reason being the intersection tool is intended to make the model dynamic to edits to any of the parameters. I suspect that part of your problem is related to the way the alignments were created. I might run some tests to verify. If you can post a subset of your dataset it would be helpful.

P.S. The intersection wizards dynamically manage the profiles as well as the horizontal geometry. Thus for example if you change the cross slope of the roadway, the edge and curb return profiles will update to maintain tangency at the curb returns and adjacent roadways.

[deltacoolguy]

How would I post a subset of the data sets?  Not sure what you mean?  Do you mean styles?  Data shortcuts?

[Neilw_05]

For a subset you could clip the terrain models and eliminate any irrelevant data.

[deltacoolguy]

Using offset alignments created with the "Create Offset Alignment" tool did the trick.

It was still a bit quirky, so I did something that I remembered reading recently on someone's blog.  I did a two-step process and created only the horizontal layout with the intersection wizard.  I ignored the vertical aspects completely.  Then, the horizontal layout popped right into place.

Then, I went back and edited the vertical stuff.  It was a tad more laborious, but in the end worked well.  Shoot, probably actually saved me time in the long run.

I have another issue regarding the vertical parameters and the curb returns.  I will start another thread for that.

Thanks for the help.

[Cadguru42]

Unless you're doing a brand new, perfect three-way or four-way intersection with equal sized lanes from all the angles, I'd stay away from the intersection wizard.  It's just faster for me to create the alignments and profiles for the curb returns manually than rely on the intersection object.

I mostly do intersection improvements, which makes the intersection object almost useless.

 The above image shows an intersection improvement I did about two years ago.  The intersection wizard and object is usless for projects like that. 

[Neilw_05]

I agree. The wizard is best suited for modeling road networks such as subdivisions or for cases where the horizontal and/or vertical is subject to variations and iterations. Each case must be evaluated in that context.

[deltacoolguy]

I like this.  A couple questions...

- Do you use the intersection wizard at all (in cases like this)?  I'm thinking after you get the parameters... alignments, profiles, etc... set-up manually.

- Do you create and/or attach your work to a corridor, or do you do mostly "free-standing" intersection designs?

- Do you have a need for cross sections?

In my case, 4 blocks of street with three intersections, the client wants cross-sections, and volumes calculated from the cross-sections.

[Cadguru42]

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@deltacoolguy wrote:

I like this.  A couple questions...

- Do you use the intersection wizard at all (in cases like this)?  I'm thinking after you get the parameters... alignments, profiles, etc... set-up manually.

- Do you create and/or attach your work to a corridor, or do you do mostly "free-standing" intersection designs?

- Do you have a need for cross sections?

In my case, 4 blocks of street with three intersections, the client wants cross-sections, and volumes calculated from the cross-sections.

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I have yet to have a single intersection project where the intersection wizard and object would work or be feasible.  I've tried it on about three different projects and I ended up just removing the intersection object and doing it manually.

I do "manual" corridor intersections where I draw out the layout as polylines, then convert the EOPs (ETWs) to alignments for curb returns, make profiles for them, and then do the corridor stuff.  

I do use cross sections for most projects, but the one I attached previously didn't really justify them because it was so short.  

Here's another project I'm currently working on.  I have no clue how to make the intersection wizard work for something like this. 

[deltacoolguy]

This makes sense to me.  Do you lose the dynamic ability to grab something... say a profile point... and make quick changes to elevations?  Or, do you have to re-create your profiles and do it all over again?

I guess another question would be, does this still allow for easy cross-sections using the corridor, etc?

[Cadguru42]

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@deltacoolguy wrote:

This makes sense to me.  Do you lose the dynamic ability to grab something... say a profile point... and make quick changes to elevations?  Or, do you have to re-create your profiles and do it all over again?

I guess another question would be, does this still allow for easy cross-sections using the corridor, etc?

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I just edit the profiles just like any other profile.  If I have the automatic rebuild turned on, the corridor immediately shows the changes.  I do not have to recreate profiles or anything.  If I did, then I might as well go back to using LDD.

Cross sections are based on an alignment, so there's no issue really, even through intersections (at least with 2012 and up since it shows other baselines).  

[Neilw_05]

Keep in mind that while you don't have to recreate the profiles, you do have to manually update them if either adjacent road profile changes. Typically with the manual approach you will create overlaps in your alignments so that you can sample the suface of the adjacent roads and match up your profiles to them.

[sboon]

The example pic posted by engrtech above is one where I would normally use the intersection wizard - twice in this case.  I like to have the centerline profiles locked together, so it's worthwhile for me.  I would only establish the offset and curb return alignments from the wizard.  The profiles and corridor I would do manually.

[Cadguru42]

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@sboon wrote:

The example pic posted by engrtech above is one where I would normally use the intersection wizard - twice in this case.  I like to have the centerline profiles locked together, so it's worthwhile for me.  I would only establish the offset and curb return alignments from the wizard.  The profiles and corridor I would do manually.

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The main road going east to west needs to keep it crown.  Because of turn lanes, the edge of pavement for the main road is skewed.  Can the intersection wizard handle that?  Also, there are three centered curves for all four corners.  I know the wizard has 3 point curves, but can it handle doing them at skewed angles?  How would it handle the side roads meeting the main centerline not at the same place?