What architects and engineers should do when creating AutoCAD DWG files for site excavation

Published August 3, 2023 by Vertigraph, Inc.

 

Most site excavation takeoff programs, including Vertigraph’s SiteWorx/OS, work nicely with AutoCAD DWG files.  When working with a proper AutoCAD DWG drawing, an estimator can complete an accurate takeoff for a complex 100-acre site in less than ten minutes. In comparison, the takeoff from a PDF file of the exact same project may take many hours or days to complete. Contour lines and points in AutoCAD drawings normally contain elevations where these objects and elevations easily import into many takeoff programs. PDF drawings are much more time consuming since elevations need to be manually assigned to each and every contour line and point.  In summary, there are overwhelming advantages, including much greater speed and accuracy, when using the DWG drawing rather than the PDF file.

As a result, always ask for the AutoCAD DWG file. If the architect/engineer requires some sort of CAD file disclaimer prior to releasing the DWG file(s), please sign this document.  If the architect/engineering fails to deliver the AutoCAD DWG files, request the PDF file that is created from the AutoCAD drawings.

In reviewing numerous AutoCAD DWG drawings, several design elements are very important. These include:

1.       All contour lines must be defined as polylines, not individual lines.

2.       All contour lines and elevation points should have elevations assigned as the z variable.

3.       Ideally, all contour lines should be solid, rather than dashed or dotted polylines, because dashed and dotted lines will end up being individual lines when the AutoCAD drawing is exported as a PDF file.

4.       The design layers should be clearly and logically labeled.

5.       Layers should contain unique definable objects. Lines, points and/or text should not be included in a single layer.  For example, the existing contour lines layer should only include existing polylines. The elevation text for these contour lines should be found in a different layer.

 

If the AutoCAD drawing is not available, for whatever reason, try to get the Vector PDF file created from the AutoCAD DWG drawing.  This PDF file must contain the layer information from the AutoCAD DWG file.  Please note: when AutoCAD exports to PDF, by default, the layer information is not exported.  As a result, the settings in the PDF export should include the layer information to ensure the layers are exported. Also, as noted in item 3 above, dashed and dotted polylines created in AutoCAD are not exported as polylines when the PDF file is created.  As a result, always try to use solid, not dashed or dotted polylines, when creating the AutoCAD drawing.

When you obtain the drawings, and you notice issues that make the takeoff more difficult, please inform the designer or architect of the problems you encounter. Feel free to link to this document to communicate this information effectively.