FLOOD01360

• County: Statewide
• Title: Hydraulic Design of Highway Culverts
• Date: 9/1/1998
• Prepared By: Federal Highway Administration
• Floodplain - Doc Type: Educational/Technical/Reference Information

ed2e confi2uration describes the entrance
type. Some typical inlet edge configu-
rations are thin edge projecting, mitered,
square edges in a headwall, and beveled
edge. The inlet shaDe is usually the
same as the shape of the culvert barrel;
however, it may be enlarged as in the
case of a tapered inlet.' Typical shapes
are rectangular, circular, and elliptical.
Whenever the inlet face is a different
size or shape than the culvert barrel,
the possibility of an additional control
section within the barrel exists.

An additional factor which influences
inlet control performance is the barrel
slope. The effect is small, however,
and it can be ignored or a small slope
correction factor can be inserted in the
inlet control equations. (appendix A)

1,5 : I TOP BEVEL
W/33.70ANGLE

'r

Ion 1ft 'I
OF BARREL i (...!.- -
HEIGHT ( I

133.70
.1-, _m_' ,

1.5

D

--i-

1:1 TOP BEVEL
W/450ANGLE

I inlft OF !{f
BARREL I
HEIGHT ; t
In inlft r\'
OF BARREL
HEIGHT ....

450

D

I

The inlet edge configuration is a
major factor in inlet control performance,
and it can be modified to improve perfor-
mance. Various inlet edges are shown in
figure 111-2. Figure III-2-A is a thin
edge projecting inlet typical of metal
pipe, figure III-2-B is a projecting
thick-walled inlet (about the same perfor-
mance as a square edge in a headwall)
which is typical of concrete pipe without
a groove end, and figure 111-2-C is a
groove end or socket inlet which is typical
of a concrete pipe joint. Note that as
the inlet edge condition improves (from
figure III-2-A to, 11I-2-C), the flow
contraction at the inlet decreases.
This reduced flow contraction indicates
increased inlet performance and more
flow through the barrel for the same
headwater.

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33.70 TOP
AND SIDE
BE VELS

1.5: I SIDE BEVEL
W/33.70 ANGLE

I inlft OF I 1.5

BARREL 1 3370 I
WIDTH (. "

B

450 'lOP
AND SIDE
BEVELS

1:1 SIDE BEVEL
W/450ANGLE

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M'I 'C I
I/,IP ft
OF BARREL' I I
WIDTH .. -
450
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Figure III-3--Beveled edges.

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