Can you guys run me through the basics on creating a surface for a shopping center? Gradings or feature lines? Thanks.
you want to to take a look at some of the old AU class videos. I'm not sure if it's caffeinated grading or another one. They go through the process of grading around a commercial site - a shopping center would fall into this category.
BASICALLY - you start out with a surface that more than covers your area and start defining inward.
HTH
RIck
First create an "Existing" surface if available using existing topo points, next take your design points or elevation info and define a "Proposed" surface. Once you have defined your proposed surface with either points or breaklines (feature lines) then you will have two distinct surfaces with which you can work with. Now you can grade around buildings at 3:1, 5:1, etc to your existing surface. You can also start grading your parking lot at this point to.
So as far as your proposed surfaces, do you just define them by tracing feature lines around everything (curbing, etc.)?
If you're talking to me, yes - that is how I'd approach it and it is in harmony with the aforementioned videos. If you're not talking to me, then nevermind!
Rick
And if you're talking to me (haha) yes you could create your proposed surface by creating feature lines around all your TBC, FL, Building footprints, etc and then ya just add them as breaklines to your proposed surface.
That's what I thought. The only other way is to combine gradings and feature lines, but gradings are a nightmare. So just put in the tedious time doing feature lines on everything and be done with it? Am I on the right track?
Yes you are...now when im doing design work its not too tedious for i usually have 3D polylines already generated from the surveying guys dumping in their fieldbook file (from the field) and CV3D then automatically generates 3D polylines between related survey points (if labeled correctly by surveyors of course) and thus I just have to use the create feature lines from object command and boom your're done! But yes if you dont have this luxury just crank em out.
You're talking about something existing. I agree. The tedious part comes when you do the proposed part.
True, but you can also start by defining your proposed surface with some elements of your existing (breaklines, points, etc) and then go in and edit those (raising, lowering, etc). Then you wouldn't have to create one from scratch. But again that's only if those things are gonna be in the same location (i.e curb) but anyways good luck with your work!
Stu
You can also use a corridor to 'frame out' the parking lot & use the resulting corridor surface to get the feature line elv's for the bld pads & curbs. This helps me by providing profile design and control of the access roads.
John
John Mayo
Are you wanting to build and existing topo surface or are you trying to create a proposed site model? It seems there are conflicting answers here based on the comments that you can use 3D polylines from the surveyors drawings which I would think represent existing topo, not proposed.
If you are modeling a proposed site then you will want to use feature lines which have many advantages over polylines for grading purposes such as true arcs vs. tesselated polys.
Gradings are the best way to keep things tied together such as edge of pavements to curbs to sidewalks, etc. but they are prone to stability problems. Also they can not model mitered corners. Thus the general consensus is to avoid using them and stick to featurelines. In that scenario any changes to the pavement grading will have to be manually applied to curbs and sidewalks which I find to be aggravating considering it could and should be dynamic.
There are ways to grade with corridors but that approach has it's downsides as well. Basically you create alignments for the edge of pavement and apply assemblies to model the curbs and sidewalks. The downside is corridors don't work well with sharp bends in the alignment and you also have to use profiles to grade the curbs which is more cumbersome than grading in plan view which generally works better for grading sites.
Another technique that is common is to create a rough grading surface for the overall site that establishes the general slopes for drainage and then drape featurelines onto the rough grade surface to build a finely graded surface model.
Depending on your site, the triumvirate of feature lines, corridors, and gradings (sparingly) seem to be the tools I use. Corridors, I think, are essential in your grading toolbox. While I haven't used them for parking lots like John, I do use them for my basins and roadways. For any graded element of your site that would have a standard-ish template, such as roadways and swales, you would be benefited by using a corridor.
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