spill slope transition under bridge

[wang890]

i need to model 3 to 1 slope on each side and under bridge is 2 to 1 and transition at the spill slope from 2 to 1 to 3 to 1. right now we have one person drew manually lots of lines to model this. 

any better way to do this?

see attached what i am trying to achieve. using grading transition doesn't work.

[AKoerner · Accepted solution]

You might try using a corridor to do it:

1. Create a new baseline with a very tight curve at the corners; match the profile to the existing road corridor geometry (a sampled surface profile tied to the road corridor 'top' surface would work, or you could make the profile 'flat' and just sample the surface elevation using a subassembly)
2. Create an offset target (pline) such that the distance from the baseline to the offset target is (or is a multiple of) the 'run' component of the desired slope.  For example, if you want 3:1, you might make the offset 3 units; where you want 2:1, use a distance of 2; add a fillet curve, converted spline, etc to handle the transition regions.
3. Create a custom subassembly that samples the offset target and converts the distance to a slope (we can help you with this if needed).  The value can be returned via an output parameter that could then be mapped to an input on your slope subassembly, or you could add the remainder of the slope geometry into the custom subassembly...
4. Create the corridor model (be sure to set the station interval on the curves to a sufficiently small value so that the 'sweep' around the corner is properly modeled)

Alternatives:

• Instead of using an offset target to control the slopes, you could use a profile on the same alignment as an elevation target where the elevation of the profile is used to control the slope value...
• You could use superelevation to control slopes, but if you do that the transition area may be difficult to define...

[AKoerner]

By the way...a quick revision...  If you want the hinge point of your slope to form a 'sharp' corner, or something closer to one than what would be produced using my original suggestion, you could use another offset target to locate the hinge point prior to adding your slope to surface, etc:

[Guillaume.Desmedt]

Hi,

Create a slope group with your corridor feature line at the top and daylight with slope variation at the bottom.

Regards

[Joe-Bouza]

How to you propose a transition a the apex? If you are concerned about the transition at the apex pull the gradings back a few feet and add the transition.

Or I missed something in the description

[wang890]

I made this in .net before but yeah i was just hoping someone had something that's better.

but anyways exactly what you said i made a custom subassembly which reads the offset value and use that as slope value. i like your style. we had the same solution for this problem. it should be a standard feature in civil 3d. for a higher quality volume estimate and better looking model.

here is a drawing showing how it's done and the pkt file. feel free to use these. it's quite a simple subassembly to make. i also added that it will go to an real offset. so if you want to cut it off at a wall it will do it. i didn't use the layout mode so you have to attach the slope value target for it to work. 

[AKoerner]

Nicely done 🙂 

Thanks for posting the sample DWG and subassembly.

[joantopo]

Hi all.

I did exactly the same subassembly for a corridor before a diagonal bridge to cover the left side( the last region) without the need to create a new baseline in the edge of the left side.

https://forums.autodesk.com/t5/autocad-civil-3d-infraestructura/genial-muestrear-obra-lineal-en-diag...