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Tips to Speed up your Civil 3D Gradings

Bennett EarleJanuary 19th, 2024

The Grading Objects in Civil 3D a great interactive design tool for us to utilize on our site design projects, however the cost of this parametric can definitely take a toll on our PCs. Here are some tips that can help ensure that your project model is running as smoothly as possible:

Excess Data

Knowing how much data to provide to our engineering models is like an endless game of searching for the Goldilocks zone. As the designer and engineer we are always looking to push the boundaries of accuracy and resolution – especially with the advent of laser scanning – and balancing it with the limitations and inefficiencies that crop up with larger and larger datasets. As we approach the grading tools within Civil 3D it is important for us to understand the data that we are providing to the software. Ask questions such as: How many points are on our EG surface? How many vertices are along my footprint? Does the tessellation of my FG surface need to be so high? What is the use-case for this model output (visualization, earthworks, QTO)? Is the mid-ordinate distance setting in my Sites too low? The answers to these questions will help you understand the detail required for your grading endeavor and hopefully give you the freedom and confidence to remove excess data that is slowing down the process.

Disable Surface Generation

A helpful feature of the Grading Tools is that it allows us – the user – to see in real-time the results of our grading design through the Automatic Surface Creation option to update our proposed TIN throughout the process. However, this surface rebuilding procedure can bog down our machines, especially if the grading area is large. Oftentimes the Grading Group TIN that is created will have many conflicting breaklines which will be categorized in the Event Viewer slowing down the entire process. Additionally, if a Volume Base Surface is provided, the earthworks calculations can have an impact on loading times as well. It is recommended that the Automatic Surface Creation is left turned off during the most intense grading edits to reduce the load within the Civil 3D model.


Consider the Footprint Geometry

Every site and grading design could be tackled in a variety of ways within our design software. There is no golden rule to determine the perfect grading scheme for every site condition and we should approach each challenge with an open mind. In general, providing the Grading Tools with bite-sized grading tasks – with minimal effect on gradings downstream – on a moderately sized feature line footprint will work best. It is recommended that roadways are graded with a Feature Line on each side and not a continuous loop. Another thing to consider is the usage of true curves along Feature Lines utilized in the gradings process to simplify the overall geometries.

Add to a Surface Definition

Another tip to remember is that we have endless flexibility in the way that we construct our proposed site grading surface. Do not feel pressured to grade absolutely everything within your grading area using grading objects, infills and transitions. Instead understand that we can add to the Breaklines definitions of our proposed surface rather than relying on an infill. This could minimize the processing time it takes to grading a closed loop roadway design – for example.

Hopefully you can try out some of these tips and have success with all of the Grading Tools (pun intended) in our Civil 3D toolbox!

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