Topic: Designing Roads to Back of Curb Rather than Centerline

[Dinosaur]

I brought this question up once but never got it resolved.  Now I am cleaning up my template and since 2009 allows saving and sharing assemblies, I would like to finally get my assemblies to really match what is going to be staked and built.

The standard practice in this area for street design is to design under the assumption that the back of curb elevations will be equal to the design centerline regardless of pavement width, turn lanes or any other factor.  Using that assumption, the back of curbs are staked accordingly and the actual centerline crown elevation is established by wherever the 2% slopes meet coming up from either side.  Please believe me, NOTHING is going to alter this methodology.  To this point, I have just ignored the problem and accepted the fact of not having true elevations at my back of curb and resort to trying to hover over the centerline at the correct station when I need a true elevation.

Is there an OOTB subassembly or method of assembly creation that will allow me to design to centerline and have the back of curb always match those elevations?  I used to draw streets in Colorado that were designed at the flowline which is pretty much what I think I need to do, but I don't Civil 3D is built to allow this and even if it were, I would expect extreme resistance at all levels.

[mjfarrell]

Sure there is.

If you think about it, you already know how.

This template uses the Left BC alignment and Profile , and Can follow A centerline Alignment and profile, use default slope. I included an ofset for the sidewalk in case it wants to meander.

[Dinosaur]

I have never tried to use anything other than the centerline design profile for the corridor.  How are the profiles for the curb lines established so this assembly can be attached to it?

[mjfarrell]

Well.....


One can design in a Centerline Profile and then Superimpose to the Curb Profiles.....
Or as you say, Curb IS Centerline, just design it that way straight off.
With the flex, Ive built into the template shown, you can even still warp the crown out
as you go through intersections.


We, (you , the others, and I) need to spend some time together so your life can get easier. And they can make some profits.   

[Dinosaur]

Well.....


One can design in a Centerline Profile and then Superimpose to the Curb Profiles.....
Or as you say, Curb IS Centerline, just design it that way straight off.
With the flex, Ive built into the template shown, you can even still warp the crown out
as you go through intersections.


We, (you , the others, and I) need to spend some time together so your life can get easier. And they can make some profits.   

The point I can't get past is what the design profile would BE at the back of curb.  I can see how to accommodate the horizontal curves and warp the profile, but I may have a short tangent and parts of two vertical curves within that horizontal curve - just accounting for the warping with one included vertical curve is stopping me cold.

[mjfarrell]

What part of including the Vertical is the STUMP?

Adding in the first place or?

[Dinosaur]

I can't even visualize such a VC.  The slopes in and out are going to be different from the centerline, the length is going to be different.  It would seem that the vertical tangents will not be truly tangent and above all else, any high and low points for both sides must line up with their brother at the centerline.  I don't know how to start creating such a beast and I would think situations where the VC spanned the stations where a horizontal curve began or ended should be equally daunting.

[mjfarrell]

Believe it or not there are tools in C3D that actually help.

[Dinosaur]

Believe it or not there are tools in C3D that actually help.

Of that Michael, I have little doubt.  After 3 1/2 years fighting what has finally become a losing battle with Civil 3D, I know that hidden somewhere in all of the obtuse interfaces, jaw breaking command names, cryptic help listings and settings that give a promise of working in multiple places yet all but one fail miserably to release their secrets, is the exact tool to do just about anything I really need to do.
Due to not exactly unforeseen circumstances, this is not as high on my priority list now to solve but I am still quite curious, especially so now that you have confirmed the existence of such a tool.  I do not know if any other user has or will ever face this particular problem, but on the off chance there are would you consider giving a few more clues?

[mjfarrell]

Stay tuned, as I am adding some touches to data that will cover some ideas about corridors this very eve.
It may not address all of the mystery you are confronting, however it let me get the rabbit in the hat.

[mjfarrell]

OK, Go check in on http://www.primeservicesglobal.com/tutorials.htm, and grab this one: Corridor Navigation Civil 3D 2009: Prospector Tab as a Teleporter, and Getting to Know your Sub-Assemblies by any other name makes life Sweet.


There are a few items in there that you should be able to use in your Curb as Design Constraint process.

[Dinosaur]

Thanks Michael . . . FYI, the r2009 interface presentation seems to have a bad link.

[mjfarrell]

No, thank you! The Link is now current.

[John Mayo]

OMG I thought we were alone on an island with the practice. TC=CL. I have tried to do this a couple of times & wound up in the same state of corridor confusion. I wound up doing the superimposition as Michael suggested.

Bear in mind I have done this on only two small projects and I have been told it is not a very good design method but it got me what I needed.

We typically have a pline of our curb from concept plans. I make it an alignment right off the bat.

I calc'd the cross slope based on cartway width. & create an assembly using link width & slope on both sides set to the calc'd cross slope.
I create a temporary corridor from the CL profile which extends well past the curbline.
I created a profile from the temporary corridor surface.
I created another profile by layout (corridor surface makes a nasty profile sometimes) to use as a design curbline that could be the baseline for the real corridor.

I did this before we had DShortcuts working so I'm thinking it may be good to keep the temp corridor in a separate file. I also held bottom of curb for the design. I think if I tried agian I would go to the TC.

One nice by product is your intersection curb returns won't need thier own profile view.

Good luck & please keep us posted. I am very interested to hear more.

[John Mayo]

"I can't even visualize such a VC"

You will once the temp corridor surface is placed in a profile. Trace & fit curves to match it.

[Dinosaur]

Great John, I am pleased that someone will be able to get some use of any forthcoming solution.  My interest is now more morbid curiosity along with a mighty dose of stubborn, but I can't give it up now.

Nice presentation Michael . . . and for anybody interested, there are about 10 downloads now available at Michael's site covering a variety of Civil 3D topics.

[mjfarrell]

Thank you sir!  Did you see anything that might help you out in there?

[Dinosaur]

I will need to watch once more sans  tonight's interruptions and digest John Mayo's contribution to be sure, but there is a glimmer of hope in there.  I found the offsets particularly interesting as I had never seen them in use before and the naming conventions  looked quite helpful as well.  one more "new" tidbit was the ability to highlight the assembly element to make different sets for each side - in our class, we still had to cycle through the selections with the space bar to do that (I never did quite get the hang of that method).  I was too jazzed last night to sleep and I am too tired to concentrate now so it is now an official weekend project.

[mjfarrell]

Right you are, things have change from the old C3D that you first met to be sure.

The tools in the video are mostly just about using Prospector to Teleport yourself around in the design.
And suggestions for letting the object names, and or group names be of some assistance in the modeling.
Later we will cover using a dummy corridor surface to  assist in our vertical design for the finished design.

[John Mayo]

I will be looking at those presentaiotns this weekend also.

Thanks!

[KW-EGA]

I found that the easiest way to do this for standard road cross-sections is just to use a vertical link at the insert point. Just calculate the elevation for difference between the back of curb and center line and add a vertical link so that the back of curb matches the profile elevation. Make sure that the VerticalLink sub-assembly is set to "Omit Link". This only works were your road cross-section doesn't vary in width or cross slope. For turn lanes and intersections, I create additional alignments and profiles at the back of curb.

[mjfarrell]

KW, one could achieve the Variable Functionality the assembly you describe lacks. Just attach a Link Offset and Slope outward from the assembly, (NOT showing the Link again) then the user would connect the Pavement, and curb Sections to the LOS. Then set the Desired Targets in the Corridor the Curb alignment and profiles control, and the Pavement Targets a Centerline Profile, and Alignment for added design flexibility.

[John Mayo]

Okay I went through the tutorial and I am left with the following questions.

1. How were the ETW & gutter PGL derived? This is the big question on the topic of designing from curb. Where you only have one travel lane you can target the CL profile superimposed onto the top of curb profile. What about the bus stop PGL?

2. Is the ETW & gutter concurrent where there is no bus stop? Do the alignments overlap? Or how do you get the outside lane of the broken back to be zero? Can you set the outside lane to zero & have it target an alignment when required?

3. How do they clean up the bowties?

[mjfarrell]

John,

I will answer all the questions in another presentation (possibly today).

Most importantly I had no bowties, and If I had (most likely with the daylight element, I could have either edit the daylight slope values in those stations as an over ride, OR attached the daylight object to an alignment to control the limits of daylighting.


The Design starts with Top of Curb PGL, and all others are derived from that.

HINT: The outside lane is Following the Lip of gutter Alignment (0.05') away from the ETW, almost like a construction joint.
Note I could have done this with a different assembly at the bus bay, that would require the use of multiple regions.

[John Mayo]

Thanks again. You have been very helpful.