Not in the Books

An organization that provides housing for financially disadvantaged families decided to develop a piece of property on a local creek.  The original design called for a sizable slice of hill on one end of the property to be dumped into the flood plain at the other end of the property.  What was left of the hill would be propped up by a large retaining wall.  Someone changed their mind, the design was scrapped, and I was called in to perform a little dirt balancing magic while salvaging as much of the original plans as possible. 

The project designer did a remarkable job for her first effort with Civil 3D.  She received formal training from a local Autodesk reseller and immediately applied what she learned to this project.  My comments are more cautionary in nature for the benefit of us all than they are criticism of her techniques.  You Civil 3D instructors out there pay attention.  Know the difference between showing a class what you know and teaching a class what to do. 

First and foremost, remember that Civil 3D is not a tool, it’s a toolbox.  Generally, it will contain the right tool for the job.  For some tasks, your pencil is the right tool for the job.

Data references are not mandatory but they certainly help.  They improve program performance, especially when working with marginal system resources.  They’re also useful when examining alternative designs without compromising the original drawings.  Start small.  Data reference just the existing surface.  Make data referencing good CAD habit.

Feature lines are your friends.  They are the premier surface modeling component – simple to create, easy to edit, and, when used as surface breaklines, dramatically reduce manual surface editing.  They also serve as finish grade features in your plans.  My rule is: if you can draw it, you can model it.

With few exceptions, point labels do not make good plan labels.  Labels associated with an object such as slope labels or spot elevations for surfaces are usually more functional.  They automatically update when moved or when the model changes.

Roadway earthwork quantities are calculated to the top of stabilization, not to the top of the finish grade.  I create my mass grading surface from the bottom of my corridor assembly allowing for one foot of cut behind the back of curb.

Don’t overlook earthwork expansion and compaction factors.  The cut factor will be greater than or equal to 1, the fill factor less than or equal to 1.  These factors are usually specified in the soils report.  Until you see the report, use 1.0 (cut) and 0.9 (fill) unless instructed otherwise.  They can make a substantial difference in your volumes.  Always let the project engineer know that you are providing adjusted numbers.

My final suggestion is to consider using -* as a suffix for some objects listed on the Object Layers tab of the drawing settings.  This technique applies the object name as a suffix to the object layer name, creating a unique layer for that object.  Then the object can be frozen independent of other similar objects although they share common component layers.  In other words, you can freeze a surface or an alignment without having to change its object style. 

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