1. PCS900 AccuGrade 3D Paving Training 3D Design Models & SVO/AGO & TBC
May 2009
Phil Jackson
CTCT Training Manager

2. Agenda
3D Designs
Design Accuracy
SVO / AGO
Differential Compaction

3. 3D Designs The design is critical
If the design is wrong the surface is wrong
Less important in grading “Because the paver can smooth it out”
You are the paver
The last chance to get it right

4. Design Types Parametric Roads TINs Grids
Each have their strengths and weaknesses
We must understand the strengths and weaknesses of each

5. Parametric Roads This is a road described by its design elements
Horizontal Master Alignment
Vertical Master Alignment
Templates
Superelevation
Widening
OR By Strings

6. Parametric Roads
Typical Parametric Road

7. Parametric Roads
Typical Parametric String Road

8. Parametric Roads This is the most accurate way to describe a road
Problem is that every program does it differently
Dozens of “road” formats to understand
PCS900 / AccuGrade UTS for Asphalt Pavers does not understand any Parametric Road formats

9. TINs TIN is a Triangulated Irregular Network
Or a mesh of triangles that describe a surface

10. TIN Models Again there are many different formats to describe a TIN
Trimble uses several
All work well in the program that designed them
Some work in other programs
PCS900 / AccuGrade uses the SVD format
Proprietary to GCS, CCS, PCS, & AccuGrade

11. Grids
Grids are rectangular (usually square) meshes where each intersection has a height assigned to it
Very simple way to describe a surface
But a coarse description

12. Grids Where is the valley or the ridge?
Grid height may miss the high or low point
Completely random with respect to the real features it describes 10 20 10 20

13. Design Format for Paving
Don’t use grid data
Unless you have a very special (unusual) case
Try to get as “raw” a format as you can
Get the parametric road data
NOT a TIN of the parametric road
Certainly not a Grid of the road
Then use SiteVision Office or AccuGrade Office to produce the SVD/SVL files for the paver

14. How to TIN a Road – Use SVO or AGO or TBC
A lot of programs can “TIN roads”
Today, only SVO/AGO or TBC can produce an optimized TIN that is accurate enough
Designed for optimum machine guidance

15. How NOT to TIN a Road
This is an example of a TINed road where the sides of the triangles are one length on the straights and one different length in the curves
A crude model that is OK for surveyors

16. How NOT to TIN a Road Take a Profile down the center of the lane
Do you want to pave this surface?

17. How NOT to TIN a Road Problem:
To make the triangles small enough to be accurate you get too many
Large model
Slow to query

18. How to TIN a Road – Use SVO or AGO or TBC
Take a Profile down the center of the lane
Do you want to pave this surface?

19. Trimble Exchange – An Engine behind SVO/AGO
This is the program that SVO/AGO uses to intelligently TIN a road
Very complex to design
Reads over 30 different road formats
Very easy to use
So easy you don’t even know it is there
Optimizes the TIN
Lots of small triangles where the surface changes
Few large triangles where the surface is constant

20. Trimble Exchange – An Engine behind SVO/AGO
Lots of small triangles
Few large triangles
Triangle density also changes across the road
Guarantees the surface to match to 1 mm
Or whatever you set it to

21. Check Your Design BEFORE you start paving, check the design
Look at the design in 3D
Be careful that the 3D picture is a true representation of your final paving design
It might be a 3D picture of the original data
Which could be different
Pull Profiles down the centers of the lanes
The edges should be smooth in all cases
Run the design in the Emulator to check what the operator will see

22. PCS900 / AccuGrade Design Formats
PCS900 / AccuGrade only reads the SVD/SVL formats which are proprietary to Trimble and Caterpillar
SVD describes a surface as a TIN
SVL describes plan detail as lines, arcs, text, & Master Alignments

23. PCS900 / AccuGrade Design Formats
Use either SVO or AGO or TBC to produce the designs for 3D paving

24. PCS900 AccuGrade 3D Paving Training Design for Differential Compaction
May 2009
Phil Jackson
CTCT Training Manager

25. 3D Designs 3D Designs describe the final finished surface
Grading systems use vertical offsets to build up to this surface
The final asphalt lift is designed to finish at this surface
But we must allow for compaction
So we need to lay the asphalt high

26. Paving & Rolling

27. Asphalt Compaction & Designs
2D Systems lay a constant thickness over the base
Therefore the compaction is constant
Say:
Design is 50 mm lift
Mix gives 25% Compaction
Therefore lay 66.7 mm
Compact 25%
Get 50 mm lift (66.7 mm - 25% = 50 mm)

28. 3D Compaction Problem
If you lay a thicker lift you get more compaction

29. 3D Compaction Problem Design Asphalt Laid Asphalt Compacted Asphalt
Design Base
Actual Base

30. 3D Compaction Solution
Design Asphalt
Laid Asphalt
Compacted Asphalt
Design Base
Actual Base
Measure the Actual Base and design the Laid Asphalt surface
Load the Laid Asphalt surface as the design

31. 3D Compaction Solution Lay the asphalt to the “Laid” Design
Thicker over the hollows
Then rolling will leave a smooth level surface

32. Differential Compaction Surface
Good for long slow changes in thickness
Bad for short sharp changes like potholes
You can’t build or roll short sharp changes 

33. 3D Compaction Solution Measure the actual base
Use UTS & SCS900
Use AccuGrade Roller or CCS900 mapping
Use GCS900 or AccuGrade mapping
Process the design in Terramodel®
Procedure is written up as a Trimble Construction Training Bulletin
“The target audience is somewhat familiar with Terramodel, SiteVision® Office (SVO) and the process of collecting data, creating a model and using that model with SVO.”

34. How to create a differential compaction surface model using Trimble Terramodel
When creating a surface model for the purpose of paving, frequently it is desired to adjust the surface for the effects of differential compaction or to make similar types of adjustments.
This document will introduce the workflows and Trimble® Terramodel® commands that can be used to create differential models.
The example project is a portion of an actual project simplified to demonstrate the technique. Users must consider many factors when modeling a job and this example may not reflect the density of the data needed to provide the desired accuracy.

35. High level summary of the workflow:
1. The user measures a surface of the original conditions. This can be done by collecting points and breaklines using Trimble SCS900 Site Controller Software.
2. The data is imported into Terramodel and an original surface is created.
3. The proposed surface is created. This can be done by importing from another format or using the design capabilities of Terramodel.
4. The difference between the existing and proposed surfaces is computed and saved as a difference surface.
5. The desired adjustments are applied to the difference surface. These adjustments can be a consistent depth or by applying a scale factor.
6. The difference surface is added to the proposed surface to create a target surface.
7. The target surface is transferred to the field system for construction.
8. The target surface is constructed and compacted with the resultant surface equal to the design surface.

36. How to create a differential compaction surface model using Trimble Terramodel
Real Answer:
It is a bit complicated but a competent data person can easily follow these instructions and produce the design
PDF of this procedure will be distributed with the class material