A.11 Culvert Entrance Loss Coefficients

Pipe, Concrete

            Projecting from fill, socket end (groove-end) 

0.2

            Projecting from fill, sq. cut end

0.5

Headwall or headwall and wing-walls:

            Socket end of pipe (groove-end)

0.2

            Square edge

0.5

            Rounded (radius = D/12)

0.2

            Mitered to conform to fill slope

0.7

            *End-Section conforming to fill slope

0.5

            Beveled edges, 33.7⁰ or 45⁰ bevels

0.2

            Side- or slope-tapered inlet

0.2

Pipe or Pipe-Arch. Corrugated Metal

            Projecting from fill (no headwall)

0.9

            Headwall or headwall and wing-walls square-edge

0.5

            Mitered to conform to fill slope, paved or unpaved slope          

0.7

            *End-Section conforming to fill slope

0.5

            Beveled edges, 33.7⁰ or 45⁰ bevels

0.2

            Side- or slope-tapered inlet

0.2

Box, Reinforced Concrete

Headwall parallel to embankment (no wingwalls):

            Square-edged on 3 edges

0.5

            Rounded on 3 edges to radius of D/12 or B/12; or Beveled edges on 3 sides

0.2

Wingwalls at 30⁰ to 75⁰ to barrel:

            Square-edged at crown

0.4

            Crown edge rounded to radius of D/12; or beveled top edge

0.2

Wingwall at 10⁰ to 25⁰ to barrel:

            Square-edged at crown

0.5

Wingwalls parallel (extension of sides):

            Square-edged at crown

0.7

Side- or slope-tapered inlet

0.2