Eng-Tips is the largest engineering community on the Internet

Intelligent Work Forums for Engineering Professionals

  • Congratulations waross on being selected by the Eng-Tips community for having the most helpful posts in the forums last week. Way to Go!

Roadway section grading in Autocad

Status
Not open for further replies.

jrm82

Civil/Environmental
Oct 2, 2006
6
US
I am trying to get a roadway section to follow an alignment in for grading calcs. I am working in Autocad 2006, with the land desktop package. I have defined an alignment (both vertical and horizontal), and saved my typical section. I can not seem to get the section to follow the alignment properly (the contours always show something slightly different). I also can't find anywhere to set how the outsides of my proposed section are to be graded to meet the existing grades; I'm looking for a 3:1 slope to meet existing. Any pieces of advice or online sources of information? I've picked a few things up from the help section in autocad, but it mostly seems worthless.
 
Replies continue below

Recommended for you

When I was grading subdivisions I tied in the contours myself, by hand. We used Terramodel, which could do the tying in for us, but for the most part we did it by hand, mostly getting the first one right and then using the offset command with a lot of trim and extend. It sounds more time-consuming, but at least you don't have contours tying in at 90 degrees creating nice 3:1 erosion channels if the contractor actually follows your plans. Also, for our subdivisions, we tied in at 10:1 for the first 100' and then 3:1 as we needed to leave a buildable building platform.
 
I use 3 road grids in land desktop development to generate a surface they are created in the cross section area menus

But first you will need to define a template for your road then use design control to generate cross sections

when you get to wierd areas like intersections and road width changes you can use 3d poly by elevation and transition the breaklines in the grids.

Hope this helps
 
Sounds like you didn't define you top surface correctly on your template.
 
Another thing to look out for is the template definition.
When I first did templates, I always drew it in a drawing that only contained the template, and I set the H & V scales to 1.

If you draw the template in your design drawing, use the template drawing routine in LDD. You don't want to just draw polylines and define it, use the routine.

Do a Google search for Land Development Desktop and the name Phillip Zimmerman. Zimmerman has written several good books.
 
Defining your template properly in LDD is the solution. The process is a bit cumbersome. I have found that the Autodesk Civil Design "Training-Student Guide" (not the user manual)to be an invaluable resource for this and many other LDD civil routines. I received it when I took a training course. It gives precise step-by-step instructions. If possible call your LDD vendor to see if you could get a copy.. or perhaps find it on-line.
 
if you are not familliar with creating the templates correctly try using this alternate method since it sound like you already have the cl elevations and slopes. Use the grading wizard and draw 3d lines manually for your centerlines and then offset them with the use of the grading wizard in LDD to creat your surface.
 
Status
Not open for further replies.

Part and Inventory Search

Sponsor

Back
Top