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<br />6 <br /> <br />e <br /> <br />Side-tapered inlets have two possible control sections, the <br />face and the throat (Figure 15). Control should be maintained <br />at the throat at design discharge, as that section is equivalent <br />to the most expensive portion of the culvert, the barrel. <br /> <br />.' <br /> <br />The required face area of side-tapered inlets may be minimized <br />by edge improvements, such as bevels and favorable wingwall angles <br />(in boxes). <br /> <br />. <br /> <br />The flow contraction at the throat of these inlets is smaller <br />than the contraction due to beveled edges. Also, since the throat <br />is lower than the face, more head is available at the control <br /> <br />section. <br /> <br />Side-tapered inlets may be used with <br />17, and 18) or pipe culverts (Figure 19). <br />a flared inlet when used with pipes. <br /> <br />either box (Figures 16, <br />This inlet is commonly called <br /> <br />Slope-Tapered Inlets <br /> <br />The slope-tapered inlet incorporates the efficient flow <br />characteristics of the side-tapered inlets with a concentration of <br />more of the total available culvert fall at the control section, the <br />throat (Figure 20). <br /> <br />e <br /> <br />The invert of this culvert is not on a straight line; however, <br />the perpendicular height of the inlet structure is equal to the <br />barrel height. As the inlet fall is increased, the slope and size <br />of the barrel decrease and the required size of the inlet structure <br />increases. (A longer structure is necessary to obtain the required <br />face area). When an excessive fall is utilized, control will shift <br />to the outlet and full barrel flow will result. <br /> <br />As with the side-tapered inlet, inlet control may be at the <br />face or the throat. The bend section, upstream of the throat, could <br />be a control section, but following the design recommendations of <br />HEC No. 13 eliminates the need to directly consider the bend section. <br />The required face area may be reduced by use of favorable edge <br />conditions, as with side-tapered inlets. <br /> <br />While the slope tapered design was developed for box culverts, <br />use of a square to round transition section permits their use with <br />pipe culverts (Figure 21). The geometry of a slope-tapered inlet <br />with non-rectangular cross section is excessively complex. <br /> <br />, <br /> <br />e <br />