I was recently asked about the best way to create a pond access ramp and after scratching my head for a few seconds, I decided to jump into Civil 3D and try a few things. I was surprised where I ended up!
After messing around with feature lines, surfaces, gradings, etc., I asked myself “Why not a corridor?” THAT tuned out to be a really sweet solution.
First, I drew a rough alignment along the inside of the pond along the path that I thought the ramp would take.
Then….this is the good part….I sampled the pond surface to create a profile. When I looked at this in profile view, I learned very quickly how well my initial guess at the alignment was. I could see the slope of the ramp as well as the mysterious bumps that I saw where the ramp when around a corner.
I learned pretty quickly that I had to change the locations of the alignment PI’s and adjust the curve radii a bit to get a smooth profile.
Then, it was just a matter of creating a simple assembly that represented the ramp in section…
And building a corridor.
To wrap it up, I created a corridor surface and then pasted it and the initial pond surface into a final pond surface.
Sweet!
One thing to add to this…the slopes used to daylight the access ramp have to be a bit steeper than the inside slopes of the pond. Otherwise they’ll just chase the pond slopes up to the top or bottom. In the example illustrated here, the pond slopes are 3:1 and the ramp daylight slopes are 2:1.
Great post. I dont think I have ever see a design like this.
What a great post!. It pays to think outside the box and use the tools given in AutoCAD Civil 3D to solve many design problems.
Great post. Nice method with the alignment, sampling, then corridor. Like everyone else I would have begun with feature lines and probably wasted a bunch of time. Thanks for taking the time to post and show us all the power of C3D.
This would be a case where a find slope path tool would be ideal. Set a max slope for the ramp and let the software trace a path. Then layout an alignment approximate to the path. It would save the guesswork.
Thanks for the post on what can sometimes be a tricky solution. At work I design ramps into rock existing quarries that have irregular slopes walls. I have often looked for a way to speed up this process as I usually have to use a combination of manual feature line and grading object work (and those grading objects sure can be buggy and crash my drawings a lot). This may inspire me to look more toward using corridors at some point. The hard part for me is that my outside road edge (the edge on the pit wall side) needs to tie directly into the existing contours rather than grade up to it (or cut into it) with a steeper set of contours as you have shown here. Regardless, your step by step has given me a few ideas I would like to explore now. Cheers!
@ Scott.
Why don’t you set your ramp sub-assembly to just go off the the left/right. Fit the alignment and profile to the quarry slope then have your new track come off the the side. You insetation point of the corridor would be either the extreme right or extreme left (depending on whether you were going clockwise or anti-clock wise). And using the SAP you can create the new profile off the existing in almost no time at all or even use the existing profile (How dynamic do you want to be?). Comment back if I haven’t made this clear and I’ll explain further. Chris
In regards to the problem of tying the road slopes to the pond, if the inside edge of the road matches the side of the pond precisely then the only slope you need to worry about is the outside slope dropping to the pond bottom. If the pond and road both are at 2:1 the road slope will just parallel the pond slope till it hits bottom.
Again, this would be a good case for having a trace slope path tool as it would find that precise seam between the road and side of the pond.
I’ve been taking a similar approach lately with access ramps down into flood control channels and basins. Another quickie that’s helped a bit is sampling half the ramp width as offsets, especially toward the basin slope side, in the initial ramp profile (like, for a 12′ wide ramp sample 6′ either side). this has helped me optimize the ramp corridor alignment to minimize cut against the basin side slope if desired.
Scott, I’m wondering if in your case you could set your alignment/profile along the outside of the access ramp, rather than the centerline. That way the slope of the pond and the slope of your access ramp would be one and the same…if that makes sense.
If you use the alignment for the edge of the road you can use the sampled pond profile as the baseline profile for the corridor. The subassemblies would hang off the baseline inward toward the center of the pond. The road would then be tied precisely to the side of the pond.
Eric
Could you explain the process of pasting surfaces in some more detail. I get an error when I try to paste my corridor surface into my final surface.
Thanks
Bueller…Bueller…Bueller…
Nate, it’s pretty simple actually:
1. Create a new surface
2. In Prospector, drill down to [new surface name] > Definition, right-click Edits and select Paste Surface.
3. Select the initial pond surface.
4. Repeat steps 2 and 3 for the corridor surface.
Hope that helps.