Topic: [C3D] Modeling a cul-de-sac with islands

[mjfarrell]

I have your geometry file as of now.
I've been deep into a MAP/GIS course all week, and today is the final wrap.
So at some point today, or through the week end I will slap it around and give you an outline of the process.
Because I've reconsidered my approach upon consideration of the geometry.


Please Stand By................

[mjfarrell]

OK, I took my first pass at this thing this morning. 
Firstly, I needed to draw all of the alignment geometry because MATT W, posted what looks like survey figure data for me to use.
Never daunted, I did use that TOPO information to build a surface just for practice.

Then I drew a Construction centerline as shown in the attached image.

I also drew left and rt Edge of pavement alignments that went around to meet the Construction CL, to create the left and right alignments and profiles needed for full control of the design for both horizontal and vertical refinement if required later.
I also created alignments around the center island, the pedestrian islands, and a left and rt drive circle centerline. These alignments follow the direction indicated by the arrows.

Then Down the Construction CL I pushed a generic template with Link Offset and Slope to both sides, with a 2.25% cross slope just for concept. I could also have create alignments and profiles for those Links to follow. The purpose of this assembly is to create my Design Reference Surface, all of my other Target Profiles will come directly from this first pass up the road, so the initial offset value was 75' to encompass the entire design envelope.  By doing this, one need later ONLY adjust this first corridor target alignments and profiles, to update the entire final design in minutes.

After pushing the first Design Planes assembly down the corridor, I then create the TOP surface. This Design Plane corridor surface is then included in the sampled surfaces for ALL other profiles, as all assemblies, and or offsets will follow this initial design surface.

Then I created the Actual Corridor Model, using tree additional Assemblies, one that is only curb to model the pedestrian islands, One that has Basic lane transition sub assemblies, on both the left and right of the baseline, and then a left and right offset with the curb attached to the offset. And one that has Curb to the left, Basic Lane Transitions left and right, and no curb on the right.

The final corridor has Three main Baselines, the Construction Cl as shown, and The Left and Right Circle centerlines.
First Baseline One Region with the Typical assembly (with offsets), this region stops near the pedestrian crossing.

Second baseline, Drive Circle RT CL, first region(assembly with no curbs right side) models the drive circle , and the north side of the north pedestrian island all the way to where the construction cl is.

Second Baseline is, Drive Circle CL, second region, uses the Typical assembly with transitions

Third Baseline, Drive Circle Left, First Region, (typical assembly with offsets) completes left half of the drive circle.

Then additional baselines and regions are used to add the curb only elements to the corridor.

All of the above regions use the alignments listed, and ALL target profiles are from the Design Plane Corridor Surface first built.

Should the design need to be modified, the horizontal and vertical can easily be modified. As the Final design then targets profiles that come from this first crude corridor, simply RT-Clicking to Rebuild is all that is required to update the model. Or that initial corridor surface can be used a reference with additional changes made to a Final PGL that is geometry  created by Tracing over the reference surface grades with additional manual edits to fine tune it.

I may revise the process slightly as part of it is bugging me a little because I think it might be a little easier, prettier, doing a couple of items just a little differently just to see.

Also, the LAST step in this process will need be to extract only the feature lines I want to use from my corridor, do to the surface boundary challenges 3d has. So the Final TOP surface will not come directly from within the corridor dialog. (Full disclosure)

I will post some screen shots later, however not the drawing, because it did not have in it what I needed to start with. So I won't be giving you back more than you gave me to work with. (I think this is fair) Now if you had posted some good geometry to work with, I just might have given you the whole enchilada.   



 

[Alan Cullen]

I know I'm going to be shot down in flames here, but still, I'll say what I want to say....nothing at all to do with C3D. Just maybe there is a correlation between how I would do it and how C3D does it. Please bare with me everyone......

In 12D I would have the outside kerb and channel lip line graded, then I would project that lip line into the centre at an appropriate distance for a cross fall of, say, 3.0%. That would form a new string. Then I would triangulate everything to a tin called "test". Then I would DRAPE the internal KNC lip line onto the tin called "test". Then I would convert the internal lip lip line into an alignment string, then I would very carefully regrade it to suit. Or most often I would just accept the result, pick relevant points on it for setting out points, and accept that the contractors grader operator knows what he is doing, and can grade correctly between the points I have given him.

That way, at the end of the day, the crossfall between the outside and inside lip lines doesn't vary too much between +2.5% and +3.5%. And let's be honest....the naked eye has a problem picking up anything up to a 1% change in grade.

I really hope that all makes some sense.

[mjfarrell]

Allen,

What you have described, makes sense to me.
I could use a similar process in C3D to use parts of the design, to lift other alignments, profiles, and or feature lines, to then use to extend the design without need to manually calculate levels or chainage along those items.

I am thinking that I need to reorder some of my baselines in regards the pedestrian islands, and how the feature lines are connecting to make the Corridor Top surfaces for this thing.

I am also considering a different set of regions and assemblies. Just because, I think there might be a more elegant solution lurking in there.

[Guest]

Michael:
The DWG I posted was basically created by a landscape architect.  I can post some of the surrounding existing grades if you'd like.  What else would you need/want/like?

[mjfarrell]

Matt,

I would have anticipated that you has drawn your geometry as polylines with line, arc segments, instead of needing to 'fake' it in the way that I did. Polyline, endpoint to endpoint, and then guessing pretty much for the curves.  However <my vetching aside> I've already drawn all of it as near enough to prove the concept so it's too late to put the cat back in the bag.


The attached is from the first procedure as described from Saturday's post.

I am rethinking my assumptions, and may post an alternate solution a little later.

[mjfarrell]

Good News and Bad news sports fans there, is a more elegant way to do this.

That's the good news!

The bad news is the 'method' that I just tried is so different from anything, I'm not even sure how to explain it.
I've possibly just created the worlds strangest set of baseline alignments, and corridor regions known to man, or woman.
Now to find a way to replicate this concept, easily.

[mjfarrell]

OK,

Final word on this, I think the optimal method is a combination of he corridor model as described above and a couple of feature lines for the pedestrian islands. Yes they can be done within the corridor, and when and where you add them has interesting impacts on the design.
There are probably about 5-6 different approaches on can take, and understanding the assembly targets, and managing multiple regions and assemblies a must. Further IF one is not very careful in ones naming conventions, and keeping the data straight, this exercise will be no fun.

And do it like a one legged Round A Bout, with only one in and out. Works pretty spiffy.