Hydraulic Design of Highway Culverts - DOT On-Line Publications

3. Endwalls and Wingwalls. Culvert barrels are commonly constructed with endwalls and
wingwalls. These appurtenances are often made of cast-in-place concrete but can also be
constructed of precast concrete, corrugated metal, timber, steel sheet piling, gabions, or bagged
concrete. Endwalls are used to shorten the culvert length, maintain the fill material, and reduce
erosion of the embankment slope. Endwalls also provide structural protection to inlets and
outlets and act as a counterweight to offset buoyant forces. Endwalls tend to inhibit flow of water
along the outside surface of the conduit (piping).
Wingwalls can be used to hydraulic advantage for box culverts by maintaining the approach
velocity and alignment, and improving the inlet edge configuration. However, their major
advantage is structural in eliminating erosion around a headwall. Additional protection against
flotation is provided by the weight of the wingwalls.
H. Long Span Culverts
Long span culverts are better defined on the basis of structural design aspects than on the basis
of hydraulic considerations. According to the AASHTO Specifications for Highway Bridges, long
span structural plate structures:
(1) exceed certain defined maximum sizes for pipes, pipe-arches, and arches, or
(2) may be special shapes of any size that involve a long radius of curvature in the crown or
side plates (50).
Special shapes include vertical and horizontal ellipses, underpasses, low and high profile
arches, and inverted pear shapes. Generally, the spans of long span culverts range from 7m to
14m (20 ft to 40 ft). Some long span installations are shown in Figures VI-35 and VI-36, and
typical long span culvert shapes are shown in Figure VI-37.
Figure VI-36--Long Span Culvert (Contech)
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