Pipe Culvert Design Spreadsheet Calculations

Where to get a circular pipe culvert design spreadsheet

For pipe culvert design spreadsheets in either U.S. or S.I. units, click here to visit our spreadsheet store.  Obtain convenient, easy to use spreadsheets for culvert design calculations at reasonable prices. Read on for information about the use of Excel spreadsheets for circular culvert design.

Inlet Control and Outlet Control for a Pipe Culvert Design Spreadsheet

One of the general conditions for pipe culvert design calculations is inlet control, in which the flow rate through the culvert is controlled at the inlet end of the culvert by the culvert diameter and other inlet conditions.  The other general condition is outlet control, in which the flow rate is controlled by the outlet conditions and the entire length of the culvert.

Pipe Culvert Inlet Control Design Spreadsheet Calculations

An equation that relates culvert parameters for inlet control conditions in a pipe culvert design spreadsheet is:

Culvert Design Equation for Inlet Control Conditionswhere:

  • HW = headwater depth above inlet invert (ft – U.S. or m – S.I.)
  • D = inside height of the culvert (ft – U.S. or m – S.I.)
  • Q = discharge (cfs – U.S. or m3/s – S.I.)
  • A = cross-sectional area of culvert (ft2 – U.S. or m2 – S.I.)
  • S = culvert slope (dimensionless)
  • K1 = 1.0 for U.S. units or 1.811 for S.I. units
  • Ks = slope constant = -0.5 for a non-mitered or + 0.7 for a mitered inlet
  • Y and c are constants dependent on the type of culvert and type of inlet.

Pipe Culvert Outlet Control Design Calculations

An equation that relates culvert parameters for outlet control conditions in a pipe culvert design spreadsheet is:

Head Loss Equation for Outlet Control Culvert DesignWhere:

  • hL = the head loss in the culvert barrel for full pipe flow (ft – U.S. or m – S.I.)
  • Ku = 29 for U.S. units or 19.63 for S.I. units
  • n = Manning roughness coefficient for the culvert material
  • L = length of the culvert barrel (ft – U.S. or m – S.I.)
  • R = hydraulic radius of the full culvert barrel = A/P (ft – U.S. or m – S.I.)
  • A = cross-sectional area of the culvert barrel (ft2 – U.S. or m2 – S.I.)
  • P = perimeter of the culvert barrel, ft or m
  • V = velocity in the culvert barrel, ft/sec or m/s
  • Ke = loss coefficient for pipe entrance

A spreadsheet screenshot for pipe culvert design calculations

 

The Excel spreadsheet screenshot below shows part of a spreadsheet for circular culvert design calculations based on inlet control.   Based on the indicated input values, the spreadsheet will calculate the minimum required pipe culvert diameter and the headwater depth for the next larger standard culvert diameter.

For low cost, easy to use spreadsheets to make these calculations in S.I. or U.S. units, click here to visit our spreadsheet store.

screenshot for pipe culvert design spreadsheet

References

1.  Hydraulic Design of Highway Culverts,Third Edition,  Publication No. FHWA-HIF-12-026, U.S. DOT/Federal Highway Administration, April, 2012.

2. Bengtson, Harlan H., “Spreadsheets for Circular Culvert Design.”, an online article.

About Harlan Bengtson

Dr. Bengtson has B.S. and M.S. degrees from Iowa State University and a PhD from the University of Colorado, all in Chemical Engineering. He is now retired after 30 years in engineering education, in teaching and administrative positions. His areas of expertise are environmental engineering, hydrology, engineering science and renewable energy. He is a licensed Professional Engineer in Missouri. He did consulting work while in academia and had prior industrial experience. Dr. Bengtson has authored numerous publications, presentations and technical reports. He is currently active as a technical writer.
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