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SAG Vertical Curve Length – Connecting Descending Grades

Curves that connect descending grades forming a bowl and its design is same as crest design of vertical curves, sight distance is a major parameter in design of these curves and other parameters which are taken in account are drainage, driver comfort and sight distance. Use this online calculator to simply your calculations.

SAG Vertical Curve

To calculate SAG Vertical Curve Length:

  • Sight Distance (S)

  • Initial Roadway Grade (g1)

  • Final Roadway Grade (g2)

  • Height of headlight (H)

  • Angle of Headlight Beam (β)

    °

  •  

Results:

  • Minimum Curve Length (Lm) in meter

  • Minimum Curve Length (Lm) in foot

Formula:

Lm = ( A×S² ) / ( 200 × (H + S ×tanβ) ) ∀ S<Lm


Lm = 2S − { ( 200 × (H + S ×tanβ) ) / A } ∀ S>Lm




If S > L, then the first formula is used, if L > S, then the second formula is used.



Where,


   

   A - Absolute difference between g2 and g1

   S - Sight Distance

   Lm - Minimum Curve Length

   H - Height of headlight

   β - Angle of Headlight Beam





Curves that connect descending grades forming a bowl and its design is same as crest design of vertical curves, sight distance is a major parameter in design of these curves and other parameters which are taken in account are drainage, driver comfort and sight distance. Use this online calculator to simply your calculations