3D Polyline Creation with reference to another by calculation

[studentga2021]

Hi All.

I'm looking into a study for road construction to resolve some practical issues to achieve best theoretical accuracy. This could be done in excel, but since I have no idea about LISP I'd like to know if it could be easier using it.

I'll try to be as simple as I can, so instead of using the 3D surface of the pavement layer I will use only a single 3D polyline that represents the ground line.

•  The initial level is 100.00 (Height:z value)
• Thickness of first layer is 0.10 (3D Poly length is 100.00 made of 10 vertexes 10.00 each)
• Theoretical level of the first layer should be 100.10 but practically because of human error it's variable 100.09 or 100.12 moving up & down as-built.
• Second layer thickness is 0.05. This means that final level should be 100.15.

To balance the up & down errors of the first layer, 2 steps of calculations will be needed on the third:

1. Subtract as-built from 100.15 and add it on the second layer thickness until it reaches the theoretical 100.15
2. Because this layer will be compacted 1/5th of its thickness should be added so after reduction 100.15 will remain as final level.

Could anyone by using lisp do any better to create a 3D Polyline like the green one which I have calculated manually on each vertex?

Sorry for making it so difficult to explain but I couldn't do any better. Attached you can check the drawing which might make it easier to understand.

Thanks 

[Sea-Haven]

Sounds like more time spent getting base correct would be better than thinning pavement. One of the reasons graders have gone to machine control to get those sort of accuracy.

[studentga2021]

In theory you're right, but what you don't know is that GPS Grader machine control is giving this accuracies. Even in the case of using robotic total stations control on graders still +- 5mm will still happen. Paving top thin layer of asphalt on hundred miles of motorways becomes expensive and what you receive won't be a nice smooth top pavement.

[Sea-Haven]

We can go back and forth and I am sure a few others could comment, but final thickness of asphalt depends on operators setting thickness (yep sonic detect) how many passes of a roller, and of course weight and type of roller.

I know that where I live the state authority does random level checks on roadworks not at plan chainages to check for this type of inaccuracy. 

[studentga2021]

The thing is real on site, already measured. Operator, GPS, or material problem, can't solve now. Is it big or small, 0.01 or 0.001 perfection doesn't exist. The final thickness depends on the roller, but the compaction achieved will always be 1/5 of the laid layer and half of bottom fluctuations are always carried up. So, if the laid layer thickness is not perfect because of inaccuracies of the bottom layer, why not make it go at the project level on top. So the absolute finished level will be like a racing pavement. This calculations correction saves time, money, and better final results on top surface for the contractors.