How Do You Grade? (Part I) Parking Lot Corridor

If you read Anthony’s post this week, you know that I am supposed to be showing you how to grade a parking lot with a corridor.  His method, using grading objects, feature lines and a reference surface is a great way to tackle it. 

But I like using a corridor for the dynamic edits….

Like this:

It would be nice if I told you how I did it, right?

All my slacker excuses on why it hasn’t been up sooner: I’ve been working on two final subdivision record plats (dang spanning labels are out to get me!) and a road grading design this week, as well as wrapping up a great municipal sewer project that one of my clients is doing as their Civil 3D Pilot AND today was Lunch with Santa. 

So you don’t get my sample drawing and “how to” just yet.  I am making sure it is a good “real” design and throwing in some drainage pipes and a few other things this weekend- but here are some hints:

In my next post, I will give you the breakdown when it is worth creating a dynamic model for your parking lot with a corridor.



  1. Sage Root says:

    I don’t remember where I read it but I have found that if you offset the direction arrow by .001 in the X and Y in the label style the spanning labels work better. Now if we could delete all labels on a parcel.


  2. yes- they do. i am working on a post for spanning labels- coming soon

  3. Steve Boon says:

    Very pretty Dana. If you add some vertical links to the bottom of your assemblies you could define the layers of asphalt and gravels, so that you could be able to calculate volumes and provide construction layout data.

  4. bryan.parker says:

    Ok Dana, how do you set the elevation of the curb only assembly? I can see how it could be done with a baseline and profile, but it’s hard to figure out what the profile should be. I could use a reference surface, but that’s not very useful (read “feature lines make me crazy) for complex grading. How do you link the elevation of the curb assembly to the parking lot centerline alignment and profile? Said another way, can I use a centerline profile for elevation, then use a baseline to align the curb assemblies with the curbs and set the curb assembly elevation at the baseline from the centerline profile? This can be done with offsets, however the curb elements remain perpendicular to the centerline. I am working on a parking lot similar to your example drawing with the parking lot in a half circle around the building and the curb bumps and islands. Any ideas?

  5. there are a millon ways we can put this together.

    i know i need to get you a sample drawing, but until then….

    my first crack at this surface is strictly boundary and maybe the lane CL marked point. I can make a surface of that corridor, and there is my reference surface. i can sample that reference surface (or export it first if i want to) then sample it onto my curb island profiles and almost trace it, then refine it.

    i also make pretty heavy use of references and expressions, they just didnt make it into those screen captures. i have labels that help me figure things out.

    alternatively, you can figure out what kind of relationship these pieces are going to have with one another and build assemblies that tack on to alignments but hold constant slope.

    also thing about this: alignments in a parking lot can be wiggly, curvy and weird. they can follow flowpaths or drainage “swales” or anything else that makes sense. they do not have to travel down the CL or anything normal….

    more to come…

  6. rlekberg says:

    Hi, I am new to and new to Civil 3D. I am a expert at LLD, but Civil 3D as been throwing me for a loop. I have not been able to get any training on Civil 3D (and for that matter, not on LLD either), and have been trying to teach myself all that I can. So far, I have been going along pretty well until it comes to parking lots. I basically do site work consistently and I try to use centerlines to layout the parking lots and to grade them. It is easier during construction for a centerline to be used with a typical section; at least I seem to get better results during construction, and it gives me better control on the grades, since every job I work on needs to be ADA compliant. The problem I am running into is that parking lots seldom follow a nice typical section like a roadway, but they are irregular. One project I am working on now has areas were parking juts in and out from a drive aisle and I want to continue a consistent slope from the centerline to the outside edge of the parking lot, where curb and gutter will be installed. What I am basically looking to do is set an alignment for the edge of the gutter that will be vertically controlled by the centerline profile in the parking lot. I don’t want to have to go through and set up a profile for the gutter edge, as I see that as a waste of time, especially when I want a parking lot centerline to control all the grades in the parking lot. Civil 3D is suppose to create the grades I want, not have me calculate each one; if that were the case, I might as well stay with LLD. The problem with using a transition lane to grade out to an alignment is that once I attach curb and gutter to the end of the transition lane, the sections where the transition lane ties into a curved curb and gutter, the section from the gutter edge out to the daylight grades are not perpendicular to the alignment used to identify the edge of the parking lot. If I were able to set the “profile” for the edge of pavement from the parking lot centerline I could then place an offset in the assembly that then would produce a more accurate section behind the curb where the two alignments are not parallel.

    I have no idea if this will make any sense to those who read this. If it would help I can email screen shots of what I am looking at.

    I have been able to do something similar in a round-about way: first create a typical section that is larger then the area I need and make a surface from that; then I set an alignment on the outside edge of the parking lot and cut a profile from the surface I just made above and use that as vertical control for the curb and gutter. It would work, except for when it comes time to calculate earthwork, where I would end up with different cut/fill.

    I just didn’t (and am unable to find anywhere) know of there was a way to have one profile pull its elevations from another profile base on a consistent cross slope.

  7. D. Aguilera says:

    that is a very interesting way of grading commercial sites… im really interested in understanding the details… is there a tutorial or step by step literature on this… i really appreciate it if someone can post a link or e-mail me… thanks.

  8. Joe Bouza says:

    I understand economy of language… But am I missing something on the how to aspect of “How to grade…..”? al I get is some images of corridor links.


  9. I did a webcast on ideas for parking lot corridors if you’d like a closer look at how this particular corridor was put together.

    Here is a link that includes the link to the webcast recording.