Superelevations in the Alignment Editor

User Q & A (Post Here)
1

Hola

The TBC Alignment editor has a couple of annoying limitations in the superelevation tab for which I have not managed to find practical workarounds.

  1. Superelevations must have the same ‘normal crown’ percentage throughout the entire corridor. I have had projects with paved sections at 2% crown and unpaved sections with 3% crown - this makes the whole superelevation tab unusable for 1 or the other sections. Duplicating the corridor and splitting/combining surfaces and linework is not only time consuming, you lose the dynamic updates for one or the other corridor.

  2. Between 2 curves the superelevation transition must either revert to normal crown or evenly rotate about the CL so the shoulders at the ‘end max super’ station of curve X rotate at the same rate to the ‘begin max super’ of curve Y. Some curves in projects I have encountered only go down to level crown or reverse crown, and TBC has no answer. I have had to either model all the supers for the whole corridor manually in a spreadsheet, or make a separate corridor for these special circumstances in only their station ranges.

I did learn that the i-Construction tools available for TBC users in Japan have some additional options, but I cannot seem to get my hands on them…

Images: https://photos.app.goo.gl/ZZzo844Lb3otXJTh7

My dream is that this could be address in the macro Edit Alignment as Spreadsheet: Edit Alignment as Spreadsheet

If anyone has encountered either of these and has a simpler way to manage it, I will greatly appreciate it!

2

Hey Nelson,

I can’t say that I’ve encountered that situation myself. I would say that you are correct in your initial assessment of the superelevation tools. Typically I consider the slope tables or sharable slope tables as a reliable fall back point for situations where the superelevation tool falls on it’s face. It may take more effort but it give the user total control of the cross-slopes within the corridor model.

That being said, I think I may have a workaround for your 2/3% scenario. I would model the corridor normally configuring my supers for the more frequent cross slope either the 2% or 3%, knowing that the others are currently wrong.

Next I would use RPS Copy and RPS Paste to duplicate the Alignment and Corridor. One I would call 2% the other 3% (You could use whatever naming scheme you prefer)

After Duplication I would modify that alignment to accommodate the other cross-slope

Then I would go through both corridors and null out the areas where the alternate cross-slopes exist.

If you would like to retain it all within one corridor then you will need to rely on the slope or sharable slope tables as you described.

Hope that helps

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I dont have my laptop available to check but i think the normal crown apploes to each curve not the entire road - i will check that next week when i am back in the office.

On the subject of supers that dont return back to normal crown are they not just supers that roll into another super before they get down to normal crown - in which case the combining super or reverse super options should be used.

In the advanced options i would have to look at your specific use case to see what is possible

You should also be able to draw a polyline in the superelevation view for the alignment and add that as a super to the alignment - there you can define whatever cross slopes at whatever stations you want and then convert to a super for the alignment

I will connect with you next week when I am back to see what is possible that you may have possibly missed and whether you can do what I think you can do - without having it in front of me it is hard to try out to solve any of your points here.

Alan

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Additional thought on this is that if you did the duplicate corridor trick you could create a third composite corridor where you just reference the other two corridor surfaces into it with the surface instructions so that you had a single corridor with both in it. You may get some wonky triangulation but without running a test I’m inclined to say it would be fine because they are both alignment based surfaces with the same alignment.

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That is how it appears but when you enter a ‘normal crown’ on any given curve it updates every other curve. They are not independent.

Now that is interesting. Never knew that was possible - thanks!

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That is what I ended up doing, and it worked fine. Plus grabbing the dynamic linework from each corridor by layer (and at the time exporting and importing them back since WM wouldn’t allow those lines as a design map.)