Hydraulic Design of Highway Culverts - DOT On-Line Publications

Figure IV-11--Inlet Edge Conditions, Face Section, Rectangular Tapered Inlets
Note undesirable design features, such as wingwall flare angles less than 15-degrees, or 26degrees
without a top bevel, are not covered by the charts. Although the large 33.7 degree
bevels can be used, the smaller 45 degree bevels are preferred due to structural considerations.
2. Multiple Barrel Designs. When designing side-or slope-tapered inlets for box culverts with
double barrels, the required face width derived from the design procedures is the total clear
width of the face. The thickness of the center wall must be added to this clear width to obtain the
total face width. No design procedures are available for tapered inlets on box culverts with
more than two barrels.
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