Monday, January 03, 2011

Civil 3D, WisDOT and Machine Controlled Grading

That's a grumpy looking badger.
 The Badgers might have lost the Rosebowl, but we're still full of WIN in Wisconsin!

My esteemed colleague Russ is presenting at the Wisconsin Society of Land Surveyors conference later this month and I'm blatantly stealing his research to blog about it.  The surveyors requested that he include information on how Civil 3D can work with machine controlled grading equipment.  Russ decided to ping  our buddies at WisDOT who are very familiar with Civil 3D and on top of the latest developments in grading technology.

WisDOT is now actively using and putting out data in Civil 3D 2010.  The first few Civil 3D projects are out the door and under construction.   Even before they went live with the product, they had been looking into mandating surface model files or a derivative thereof.  At the moment, they are nowhere near the point of requiring surface models, but they have several pilot projects in the hopper that will help them determine the future of Automated Machine Guidance for highway projects in Wisconsin.

Brad Hollister, PE, is part of the team at WisDOT that is integrating technology into the entire WisDOT work-flow.  In addition to being an all-around great guy, he is a big proponent of Civil 3D and the streamlining that can be done to the construction process with the data that results from corridor models (which he calls Roadway Models in the email that follows).

As part of Russ' research, he contacted Brad to see what the scoop was with AMG today.  Brad's email response is included here:
Right now WisDOT has language in our Standard Specifications addressing Automated Machine Guidance. The current spec places the burden of Roadway Model development on the contractor, a necessity considering our design environment which uses CAiCE. As our C3D implementation progresses, it will allow us to reconsider this policy regarding Roadway Model development.

We’ve already seen a few WisDOT design projects finished in C3D, and we are conducting a series of 4 pilot projects this year in which we are sharing Civil 3D proposed surfaces (Roadway Models) with contractors for Automated Machine Guidance operations. One important aspect of the pilots is that we are making our Roadway Models available to contractors prior to LET.

At a minimum, Automated Machine Guidance (AMG) operations will need roadway alignments and proposed surfaces from design, and control from project survey.

Project control consists of points, and can be shared in any number of formats, LandXML or text files work fine.

For roadway alignments, we are trying out LandXML version 1.2. This year’s pilots will tell us how well LandXML works for sharing our C3D alignments with contractor software.

For surface sharing, LandXML is an option but it is not the format we are using in the pilots. The reason we are not using LandXML is that given our typical project size the LandXML surface files can be pretty big, and we’ve seen import problems with these huge surface LandXML files in the past. Instead, we are taking our Civil 3D surface DWGs, viewing the surface with a triangles-only style, and exporting the file to AutoCAD 2004 DWGs. Each resulting surface DWG contains a single surface represented by 3DFaces. In the past we’ve had success sharing large surfaces with contractors using the AutoCAD DWG-3DFaces format. At some point in the future we may try surface sharing in LandXML again but for now we are recommending AutoCAD DWG.
We are sharing 4 Roadway Model surfaces for each construction stage of the project:
  • Datum (for grading operations)
  • BaseCourse (for base placing and trimming operations) 
  • Top (to help contractors interpret design intent)
  • Exist (for verification of Existing ground accuracy in the field, for earthwork quantity manipulation to aid in bid preparation, and to allow contractors to recompute earthwork quantities for alternative staging sequences)

  One other item of interest to consider is the overall intent of the Civil 3D design workflow we are using at WisDOT. One of the goals of our C3D design workflow is to develop construction-ready Roadway Model surfaces directly from design, surfaces that will not need additional modification by contractors for AMG operations. This year’s pilot projects will help us determine if our workflow meets this AMG-ready Roadway Models goal. Ultimately WisDOT is looking to make AMG-ready Roadway Models a deliverable of the design process on all our projects, although there are many considerations to address before the Roadway Model deliverable requirement is implemented.
Hopefully the next steps will have them digging deeper into the model (pun intended) and as technology evolves, integrating more direct links between Civil 3D and their contractors' software.