Culvert Design

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Culvert Design

• Material Selection
• Central Office Hydraulics

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Steps for Material Selection

• Field Review
• Culvert Hydraulics
• Structural Strength
• Service Life
• Material Analysis
• Plan Alternates

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Field Review

• Determine pH of the water
• Use an instrument that is capable of accuracy of
  0.1
• Use Figures 1002-2 through 1002-3 only if no flow
  is present when performing the field check

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Do not use unless there is no flow when
performing the site visit.
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Field Review

• Determine if there is a presence of abrasive
  material.
• Abrasive Material Presence of gravel, stones,
  or a course sand in the barrel of an existing
  conduit (or in the existing stream bed) that has
  a stream gradient or flow sufficient to cause
  movement of the abrasive material.
• Assume abrasive conditions if there is any
  question about the bed material.

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Abrasive Condition
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Non-Abrasive Condition
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Field Review

• Investigate the condition of existing structures.
• If a replacement structure, look at the existing
  structure.
• If a new structure look at any adjacent existing
  structures.

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Culvert Hydraulics

• Use approved methods outlined in the Location and
  Design, Volume 2 Manual

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Structural Strength

• Structural strength for Metal Conduits (steel and
  aluminum)
• Select the gauge thickness and corrugation
  profile that is adequate (based upon fill
  height).
• Figures 1008-1 through 1008-9 (steel)
• Figures 1008-15 through 1008-21 (aluminum) (NOT
  Aluminized)

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Structural Strength

• Structural Strength for Concrete Conduits
• Select the D-load that is adequate for structural
  strength (based upon fill height).
• Figures 1008-10 through 1008-14

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Service Life

• Service life is either 50 or 75 years
• Use 50 years as a minimum .
• Use 75 years for high fills (gt16), under
  freeways, or where future costs may be high to
  replace the structure.

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Service Life

• Durability for Metal Conduits
• Use the obtained pH and abrasiveness observation
  to determine the gauge thickness.
• Use figures 1002-5(50) through 1002-6(75) the
  general notes for the figures.

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Service Life

• Durability for Concrete Conduits
• Check for adequate service life based upon the
  pH, pipe slope, and pipe rise.
• Use figure 1002-4.

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Material Analysis

• For metal conduit, choose the higher gauge
  thickness from the structural design, or the
  durability analysis.
• When durability thickness is higher than
  structural thickness, provide the 1-inch
  corrugation profile for pipe diameters over 48
  inches.

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Plan Alternates

• Place all available material options in the plan
  (all metal alternatives and concrete).
• In some cases, only one material may be specified
  in the plan
• If the outlet velocity in a concrete pipe
  requires a ring chamber and the velocity of the
  metal alternative is below 20fps, then metal may
  be used exclusively.
• When encountering excessive cover for a concrete
  pipe.

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Plan Alternates

• Where a larger corrugated metal pipe would
  require a higher pavement grade to satisfy
  minimum cover requirements, concrete may be used
  exclusively.
• Where a metal pipe arch is required hydraulically
  and a round concrete pipe would work, concrete
  may be used exclusively.
• Do not need to specify minimum D-loads or minimum
  gauge thicknesses in the item call-out.

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Plan Alternates

• Show the following in the plan
• D-load or gauge thickness if it is above the
  minimum shown in the specifications.
• The conduit shown in the plans should be the
  longest length pipe (the smallest diameter).
• Hydraulic Design Information
• Other information (see LD, Vol. 3, Section
  1312.2)

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Example Problem

• Given
• Hydraulic design requires 96 inch corrugated or
  90 inch smooth lined
• Outlet velocities
• Corrugated V17.0 fps Smooth lined V21.0 fps
• Height of cover 18 feet
• Under a new alignment (minor state route)
• pH was measured and found to be 7.5

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Design Example
Photo from creek Is this Abrasive?
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Example Problem

• Select the appropriate design alternatives.
• As per LD, we will exclude concrete conduit in
  the design due to the velocity of 21 fps.
• Durability Design
• Site was determined to be abrasive in nature
• A design service life of 75 years will be used
  due to the high fill height.
• Use Figure 1002-6(75) for the durability design

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Example Problem

• Options from figure notes are
• 10 gauge 707.02 Aluminum Coated
• 12 gauge 707.07 Aluminized Asphalt Coated
  Paved
• 14 gauge 707.04 Polymer Coated with 1
  corrugations
• 16 gauge 707.04 Polymer Coated Asphalt Coated
  Paved
• 16 gauge 707.02 with Concrete Field Paving
• 1 gauge 707.03
• 12 gauge 707.03 with Concrete Field Paving
• 707.22 (aluminum pipe) with Concrete Field Paving

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Example Problem

• Structural Design of Metal Conduit
• Use Figure 1008-1 1008-3 to check for maximum
  height of cover

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Example Problem

• A gauge thickness of 0.064 (16 gauge) will be
  satisfactory up to a fill height of 31 feet for
  all steel options except for 707.03 (structural
  plate).
• A gauge thickness of 0.109 (12 gauge) will be
  satisfactory up to a fill height of 29 feet for
  steel structural plate.
• A thickness of 0.105 (the minimum for this size)
  will be satisfactory up to a fill height of 20
  feet for aluminum pipe.
• A thickness of 0.100 (the minimum for this size)
  will be satisfactory up to a fill height of 20
  feet for aluminum structural plate.

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Example Problem

• Specifying in the Plan
• Specify the alternative as per LD, Volume 3,
  Section 1312.3.
• For this example it would be as follows
• 603 180 L.F. 96 Conduit, Type A 707.02 (0.138)
  Aluminized, 707.02 with CFP, 707.03 (0.280),
  707.03 with CFP, 707.04 (1) (0.079) Polymer
  Coated, 707.04 (1) Polymer Coated Asphalt Coated
  and Paved, 707.07 (0.109) Aluminized Asphalt
  Coated and Paved, 707.22 with CFP, 707.23 with
  CFP

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Questions ?