SUDA Tip – Best Practice for Headwall 3D cells

Written by: Robert Garrett

When configuring the 3D cells of head walls for use in SUDA, there are some required construction points to be created in the cell.

  • Alignment Point – a point of construction class and line style of 3 is used to align the 3D cell with the 2D cell used for plan view presentation.
  • Elevation Point – point of construction class and line style of 5 is used to define the elevation point of the head wall.

Traditionally, these points have been collocated in the 3D cell and placed at the flow line.  This was based on the assumption that “top elevation” had limited meaning for a head wall.

MicroStation 3D cell SUDA Subsurface utility headwall

However, a better practice is to place the Elevation point at the location on the head wall where the ground surface (existing or proposed) would intersect the head wall.

MicroStation 3D cell SUDA Subsurface utility headwall

The advantages to this approach are:

  • When placing the head wall, the elevation point will be assumed to lie on the selected surface and the flow line elevation will be thus be automatically determined.
  • When reviewing properties or reports of the head wall, both the surface elevation and flow line elevation will be reported.
MicroStation 3D cell SUDA Subsurface utility headwall

Contact us if you need assistance creating your own 3D cell libraries for SUDA.


Robert Garrett

Robert has over 25 years experience as a practicing engineer and is licensed in the State of Tennessee. After graduating from Tennessee Technological University, Robert worked for the Mississippi State Highway Department, Bridge Design Division. Then he spent 12 years with the Tennessee Department of Transportation in the Roadway Design Office and later served as Regional Manager in the Design Survey Office.From 2000 to 2006, Robert worked for Robert G Campbell and Associates in Knoxville, TN where responsibilities included roadway, site, and utilities design projects.Joining Bentley Systems in March 2006, Robert wrote specifications & documentation for software development. Duties included testing, customer feedback and ensuring the products met the needs of the civil engineering user base. He also developed training material for education both internally to Bentley and for outside organizations. He served as Product Manager for Utilities Products, including the new OpenRoads Subsurface Utilities Design and Analysis software. Robert also provided guidance and implementation services for new technologies.He is a frequent presenter and trainer at user conferences.


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