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Appendix C-Comparison of Round and Rectangular Culverts

These tables show the open-end area of round culvert pipe and the open-end area of rectangular timber culverts.

Round Pipe Culverts
Diameter
(inches)
8 10 12 15 18 24 30 36
End area
(sq. ft)
0.4 0.6 0.8 1.2 1.8 3.1 5.0 7.1
Rectangular Timber Culverts
Height
(inches)
Clear width (inches)
20 24 30 36 48 60 72 84
End area (sq. ft)
5 0.7 0.8 1.1 1.3 1.7 2.1 2.5 2.9
11 1.4 1.8 2.3 2.8 3.7 4.5 5.5 6.4
17 2.1 2.9 3.6 4.3 5.0 7.1 8.5 9.9
23 2.9 3.8 4.8 5.8 7.7 9.6 11.5 13.4

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Updated: 04/14/2014
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