Cul-de-sac design process

[John Fowler]

I am trying to work out how to create a cul-de-sac from start to finish in 12d. I'm familiar with doing this in CivilCad and in that the cul-de-sac editor is buggy and useless, so it was pleasant to see the 12d one gives a decent horizontal geometric layout at least.

In CivilCad my methodology for designing a cul-de-sac is as follows:
- Create centreline and give it vertical geometry
- Create standard road template and apply it up until the start of the cul-de-sac head
- Create alignment which is comprised of the horizontal geometry for the head of the cul-de-sac
- Manually work out levels around the cul-de-sac head to try to ensure sufficient road crossfall and gutter longitudinal fall, then apply a gutter profile and batter template to this second alignment which is the kerb alignment of the cul-de-sac head
- Transfer all the design strings from both alignments back to the survey view, manually trim intersecting parts of the two designs and then create a design dtm from the trimmed strings

Now obviously the above method has problems in that it is both time consuming and takes a while to change and re-update the design if something has to change later.

Now, in 12d, my method I am trying so far (after reading the getting started guide and what help I could find online) is as follows:
- created my centreline and converted it to a super alignment of which I have defined the vertical geometry
- created a template to apply to the road and applied it up until the start of the cul-de-sac head
- I made the mtf file that has my templates selected in it
- created the horizontal geometry of the cul-de-sac head using the 12d cul-de-sac creator, I then made this into a super alignment and got 12d to vertically grade it for me based upon the grades of the connecting strings at either end (4 point method or something I think it was called)

Now here is where I run into trouble. I created a Apply many function and loaded the mtf file into that. I can't work out how to grade my design surface for the head of the cul-de-sac. I tried using the mtf modifier to give a fixed grade to the kerb string of the head although couldn't get it to work.

Any tips or suggestions on how to do it or what is the correct/best way to create a cul-de-sac from start to finish in 12d would be appreciated. I am hoping that 12d has a better process than what CivilCad does - I'm guessing I could probably use a similar method in 12d as I do in CivilCad although am hopeful there is a better way.

The picture below shows what I worked out how to do and where I got up too:


Cheers

[Matthew Monk]

You're almost there. As with most things in 12d, there's usually more than one way to do it, so I'll just explain how I would do it.

Assuming your cul-de-sac alignment has full horizontal and vertical geometry on it, I would create an Apply Many function for just the cul-de-sac string. The Apply Many (AM) function would use an MTF, which, in turn, applied a template around your cul-de-sac string. In this case, the template would be the kerb profile itself and anything behind the kerb (e.g. footpath, verge)- effectively the same as your half-road template, but without the road/lane width part. Just start at the start of your kerb. This would be applied on the left side in your MTF based on your screenshot.

If applied correctly, this would create kerb strings around the cul-de-sac. You could then triangulate these strings with your approach road strings, but you'll probably get a flat bit inside the cul-de-sac bulb. To fix that, I would normally create a crown string that extends from where the approach road templates currently stop until the end of the road alignment. My method for doing that is to simply insert a zero-width, zero-height/xfall link for that distance. You can do this either by creating a basic template, e.g. CLIN ONLY (make sure to set the final cut/fill to no slope), or use a modifier command, Fixed Insert, to achieve the same result. This will mean that you've got the road strings, which includes a single centreline up to the centre of the bulb, and the kerb strings around the cul-de-sac. Triangulate all of that up and you should have everything sorted.

Some may say that you can just triangulate the road and kerb alignments themselves, but I prefer not to do that.

Hope that makes sense. Let me know if there's anything that's not clear.

If you really wanted to get into minimal re-work on layout/grading changes, you could build up the cul-de-sac alignment with computators and run things in chains.

[John Fowler]

You're almost there. As with most things in 12d, there's usually more than one way to do it, so I'll just explain how I would do it.

Thanks for the explanation.

Assuming your cul-de-sac alignment has full horizontal and vertical geometry on it, I would create an Apply Many function for just the cul-de-sac string. The Apply Many (AM) function would use an MTF, which, in turn, applied a template around your cul-de-sac string. In this case, the template would be the kerb profile itself and anything behind the kerb (e.g. footpath, verge)- effectively the same as your half-road template, but without the road/lane width part. Just start at the start of your kerb. This would be applied on the left side in your MTF based on your screenshot.

If applied correctly, this would create kerb strings around the cul-de-sac.

Aha, this is what I was fundamentally missing and didn't realise, even though this is the method I wrote of using in CivilCad! Putting a gutter/footpath/batter template on the kerb string achieved what I wanted too.

You could then triangulate these strings with your approach road strings, but you'll probably get a flat bit inside the cul-de-sac bulb. To fix that, I would normally create a crown string that extends from where the approach road templates currently stop until the end of the road alignment.

When you say a crown string, is that a specific 12d term/string or is it simply a normal string along the crown of the road? What I done in the end was to extend my horizontal alignment up until the end of the cul-de-sac road pavement (CH116) and give that vertical geometry so the cul-de-sac head had better drainage.

My method for doing that is to simply insert a zero-width, zero-height/xfall link for that distance. You can do this either by creating a basic template, e.g. CLIN ONLY (make sure to set the final cut/fill to no slope)

I done this. Thanks for reminding me about removing the default cut/fill slope values as I almost certainly would have forgot to initially do that. I then contoured all the design strings from both alignments (including my zero width template applied in my MTF file on the main CL alignment after the end of my full half road width template).

Completed model


If I update/modify a template that I am referencing in a MTF file, why does the Recalc => Recalc all function not then use the updated MTF file accordingly and update my design to use the changed template? I am finding myself having to edit the MTF file and click Recalc on the MTF panel. Is this normal?

Similarly I made a function that grades the kerb line around the head (kerb return apply) and I found when going Recalc => Recalc all it didn't work/update although if I went Recalc => manually select the function name and run it, it did work and update. Is this normal or is this where I need to use computators/chains as you mentioned?

or use a modifier command, Fixed Insert, to achieve the same result. This will mean that you've got the road strings, which includes a single centreline up to the centre of the bulb, and the kerb strings around the cul-de-sac. Triangulate all of that up and you should have everything sorted.

I had trouble with this at first although got it to work in the end.

If you really wanted to get into minimal re-work on layout/grading changes, you could build up the cul-de-sac alignment with computators and run things in chains.

While I haven't tried this yet, this is my intention. I'm trying to decide whether I want to learn fully the 12d or the Civil 3D packages at the moment and the ability to update the design as easily/quickly as possible after minor design changes is important.

From what I understand, in Civil 3D if I create a road surface and place drainage pits and pipes in the road surface, and then later modify the road grade/surface, the pits/pipes will attempt to automatically adjust themselves accordingly. Does 12d have this same functionality or are the drainage module (which I haven't tried yet) and road module not able to be linked together like this?

Thanks

[Matthew Monk]

Ok, that screenshot looks good and is basically what you're aiming for.

Aha, this is what I was fundamentally missing and didn't realise, even though this is the method I wrote of using in CivilCad! Putting a gutter/footpath/batter template on the kerb string achieved what I wanted too.

Effectively, for building up your 3d model and surfaces (tins), you're just generating 3d strings. 3d strings are triangulated to make up your surface. How you create those 3d strings is up to you. For anything where strings are parallel to another (e.g. kerbs, roads, channels, linear stuff), templates and Apply Many functions are often the easiest way to create those 3d strings. Nothing is technically stopping you from creating each individual kerb string as a Super string (*shudder*) or a Super Alignment, just that it's inefficient.

When you say a crown string, is that a specific 12d term/string or is it simply a normal string along the crown of the road? What I done in the end was to extend my horizontal alignment up until the end of the cul-de-sac road pavement (CH116) and give that vertical geometry so the cul-de-sac head had better drainage.

Yep, not a 12d-specific term, just a string to represent the high point within the cul-de-sac. That, of course, assumes it grades like most- from the centre out. It could just as easily be an invert if the cul-de-sac grades into a central road invert (e.g. laneways).

I don't use Recalc All at all. For an explanation, see here:
http://forums.12dmodel.com/viewtopic.php?t=6091

I would probably use chains these days. Most people would (should?) be doing the same. It really is a much more efficient way of recalcing, particularly for design changes.

I'm trying to decide whether I want to learn fully the 12d or the Civil 3D packages at the moment and the ability to update the design as easily/quickly as possible after minor design changes is important.

I may be slightly biased, but I would consider 12d to be more flexible for accommodating design changes. Stick with 12d, I say

As for the drainage stuff, yes, the pits and pipes can be updated to suit the latest design. You can set pit levels based on a tin or a particular string (e.g. back of kerb) and pipe levels based on min. cover. All of these can be updated in a chain, too.

[John Fowler]

I don't use Recalc All at all. For an explanation, see here:
http://forums.12dmodel.com/viewtopic.php?t=6091

I would probably use chains these days. Most people would (should?) be doing the same. It really is a much more efficient way of recalcing, particularly for design changes.

I can't access that part of the forum. Are you able to copy your explanation to this thread?

I modified my design to use a basic chain instead and it worked (and did what I expected the recalc all function to initially do).

If I want to create a final tin comprised of the design surface and natural surface, how do I do this in a chain so it is done automatically if the design changes? I worked out how to create a supertin to combine the two surfaces, although I couldn't work out how to incorporate this into the chain. Any tips?

As for the drainage stuff, yes, the pits and pipes can be updated to suit the latest design. You can set pit levels based on a tin or a particular string (e.g. back of kerb) and pipe levels based on min. cover. All of these can be updated in a chain, too.

That is good to hear.

[Matthew Monk]

The Auto Recalc Mode for a Function sets a flag for that function that defines whether it can be recalced automatically. The recalc is done from the Recalc All option (Utilities->Recalc->Recalc All). That panel re-runs all functions that have had their auto recalc flag set. There is an additional option on the Recalc All panel to ignore the flag- if ticked, all functions will be recalced regardless of any auto recalc flag.

To be honest, I've never used it that much and these days I'd prefer a chain anyway where I have more control and greater flexibility over which functions are run and in what order.

As for Super Tins, one of the great things about them is that once they're created, they're always up-to-date. You rarely have to do anything else once a Super Tin is created, except maybe a screen redraw. A lot of people, myself included, would usually have as the final command in a chain the Redraw All Views.

[John Fowler]

The Auto Recalc Mode for a Function sets a flag for that function that defines whether it can be recalced automatically. The recalc is done from the Recalc All option (Utilities->Recalc->Recalc All). That panel re-runs all functions that have had their auto recalc flag set. There is an additional option on the Recalc All panel to ignore the flag- if ticked, all functions will be recalced regardless of any auto recalc flag.

To be honest, I've never used it that much and these days I'd prefer a chain anyway where I have more control and greater flexibility over which functions are run and in what order.

Thank you.

As for Super Tins, one of the great things about them is that once they're created, they're always up-to-date. You rarely have to do anything else once a Super Tin is created, except maybe a screen redraw. A lot of people, myself included, would usually have as the final command in a chain the Redraw All Views.

That is handy to know.