Math wizards question

RobertEVs
Advisor
Advisor

Math wizards question

RobertEVs
Advisor
Advisor

How would you determine "X" and "Y" when you have a 1% slope or anything except 0%? 0 would be easy to determine.

 

2024-04-26_09-14-33.png

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fcernst
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Mentor

Jeff’s diagram shows the issue with Civil 3D where profiles, surfaces and corridors are not offset orthogonally to the profile….or a surface is not offset planar normal to the surface plane. The vertical offsets in Civil 3D are not relative to the object plane orientation.. just simply absolutely vertical. 

 

Joe and I interpret the original diagram as 90 degree angles with the triangle height always perpendicular to the base .. no matter the base absolute rotation. 



Fred Ernst, PE
C3D 2025
Ernst Engineering
www.ernstengineering.com

Joe-Bouza
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Mentor

I see the effect that @RobertEVs  and @Jeff_M  are computing. but this raises another question. if the flow line slope is 2% then the upstream length become 9.1-feet and down stream become 5.9-feet which looks wrong, 

Joe Bouza
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CahaLF7RX
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Hello again,

Depending on what your standard curb height is.

For most projects I have worked on (for 33+ years) the standard has been 6-inches.

if the road vertical slope in not 0.0% (which is not practical for drainage), the ramp lengths will be different lengths (using the 1:12 max slope) or can be different slopes and the same length.  depends on who is sealing the drawing.

good luck,

nonbeard13

 

fcernst
Mentor
Mentor

This discussion has digressed and permutated from the original diagram for isolating and computing x for completing the small triangles at a relative 7.5% within the small triangles workspace domain .. to an absolute 7.5% constraint now for civil grading work. There were no parameter caveats stating this in the original diagram. For example, it originally to appeared to be  a simple trick question.. that now the OP doesn’t realize he subsequently posited. 



Fred Ernst, PE
C3D 2025
Ernst Engineering
www.ernstengineering.com

Joe-Bouza
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I agree with you. I was only show the it impractical to use the flow line as a basis

Joe Bouza
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teerawat.pSCHYQ
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my understand that slope 7.5% are related with that 1%, and you talking about design profile for something. this is my idea about this,  if you create like a profile, and then add labeling for the tangent slope length, then you can get the correct slope length like this.  

teerawatpSCHYQ_1-1722314290644.png

 

 

Joe-Bouza
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Mentor

I agree with you. I was only showing that it is impractical to use the flow line as a basis

Joe Bouza
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