Corridors for Everything

render1.png (Except the building, this entire site was modeled using ONE corridor)

I had one of those Third Semester Calculus Moments over the weekend. Suddenly, I saw everything as a corridor. I have always seen roads, streams, swales, berms, walking paths and others as corridors. But what about Parking Lots? Sanitary Lagoons? Gumby? I began wondering if everything could be explained in terms of a Corridor. Easy ones- trash cans, pencils, sure, but what about cars, Barbie Dolls, cheesesteaks?

The key–the real key is–you must think in profile.
When I first watched the webcasts about making intersections…and they said you had to profile your gutter line around the intersection, I thought they were NUTS. I couldn’t think that way! I could only think with a red pencil, a scale and a model space check plot.

Then I did it a few times. And suddenly, I understand the world better in profile.


Everything done here could be done with a combination of feature lines and grading objects, but think about revisions. Feature lines in small doses are easy edits, but not large batches. And they don’t react to each other. However, if I grip edit a profile that represents the curb around a median, I’m in business. And the “edit profile geometry” interface isn’t much different from the feature line editor anyway.

Don’t forget your Reference and Expression Labels.


Here are some screen captures and ideas on how you can build a corridor to model just about anything- if you use your imagination. And here is a hint- don’t get caught up in making every single inch of your site an assembly. Just let the TIN figure it out in the open areas.


How about this site? Indeed yes. I see one corridor. I will post it someday soon when I have a chance to render it.parkinglot3.png



  1. Pesto says:


    That looks great and would make labeling, earthworks, etc. easy. I do have concerns though. How many profiles and alignments did you use to create this? How easy would it be to make changes to this site? I do recognize that once the changes to the profiles are corrected everything else follows.

    It looks great!

    David J. Pesavento
    Morton & Pitalo, Inc.

  2. MAnderson says:

    Dana –

    You have my attention. It is a very interesting concept. As I have worked with feature lines and grading objects and CER reports to Autodesk for production, I have wondered if there was a better way.

    I might have to spend some good quality C3d time instead of sleeping.

    Matt Anderson

  3. omegared1978 says:


    What a great concept. I will definitely be waiting for your post on this parking lot project. My only request is that you keep a record on how long it took you to corridor the parking on your first attempt. In addition, how long it takes you to do it with ease and accuracy.

  4. Dana Breig Probert, EIT says:

    The Corridor for the rendered/horseshoe parking lot is amazingly simple. It is three baselines with one region each. EOP Left, EOP Right, CL. That’s it.

    I ran it a few ways- sometimes I did the EOPs as transitions, sometimes I didn’t. It really depends on your design intent- the model can reflect whatever constraints you have.

    As far as how long does it take to do this…. the first one you try will take you a long time. Probably longer than many people have the patience for if they don’t see the value.

    Since this is what I do for work and for fun, I stuck with it and figured it out.

    The horsehoe took me about 3 hours to fully model (being as I was figuring out my technique at the same time) I would say that if I had a similar site, once I figured out my design constraints, it would take me about 1 hour to model. The design, however, would take as long as it takes to optimize my site.

    Accuracy- this is as accurate as it gets. I put in addtional PIs and PVIs as I would need spot elevations if I was doing by hand.

    The larger parking lot- I will report when I am finished with it.

    Edits- I would estimate edits would be similar to when I have my large 52 baseline corridors for subdivisions. Major edits go quickly if I build my corridor empty. Just split my VP and work through my plan and profile watching the labels update. Every so often,rebuild the corridor and have a look at the surface.

    remember- MODELING does not equal DESIGN

    these sites take a long time to get the model properly built.

    Once built, you iterate your design as much as you need to- and you will get your contours and labels changing with you.