Hydraulic Design of Highway Culverts - DOT On-Line Publications

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Conclusions: The selection of a side-tapered or a slope-tapered inlet would be based on economics since either design will pass the required Q at the ELhd of 96 ft. Dimensions: Corrugated metal side-tapered inlet: Smooth slope-tapered inlet, vertical face: D = 48 in D = 48 in Bf = 6 f t Bf = 6 ft TAPER = 4:1 Sf = IV:2H L1 = 4 ft L1 = 8 ft L2 = 5.6 ft L3 = 2.4 ft Face Edge Configuration: Beveled edges Face Edge Configuration: 45-degree Min W = 10 ft 90-degree wingwalls with bevels on the top and sides 122
A. The Routing Concept V. STORAGE ROUTING Storage routing is the calculation of the change in shape of a flood wave over time. A pronounced shape change occurs in a flood wave when a significant storage volume such as a pond or a reservoir is encountered. The storage concept can be visualized by means of a hypothetical situation (27). In this situation, a spigot discharges water into an empty barrel which has an orifice (hole) at the bottom (Figure V-1). A plot of the inflow and the outflow reveals some important characteristics of the storage routing process. Figure V-1--Hole in the barrel analogy Figure V-2--Inflow and outflow hydrographs The spigot is turned on at t=0 and discharges a constant flow rate, Qi, until t=ti, at which time the spigot is turned off. The flow rate entering the barrel exceeds the discharge capacity of the hole. This results in the storage of water in the barrel. As the depth increases, the discharge of water through the hole increases due to the rising head on the hole. The maximum outflow is reached at a time when the depth is at a maximum. This peak outflow occurs when the spigot is turned off since there is no additional inflow after that time. Figure V-2 is a schematic representation of the inflow and outflow hydrographs. Additional information about the storage routing concept may be obtained by examining Figure V-2 more closely. An area on a graph of discharge versus time represents a volume; that is, a discharge increment multiplied by a time increment. The area under the inflow hydrograph depicts the volume of water entering the barrel. The area under the outflow hydrograph depicts the volume of water leaving the barrel. The area between the two curves is the volume stored in the barrel. This volume (area) reaches a maximum when the spigot is closed. From that point on, the area under the outflow hydrograph represents the discharge of the volume stored in the barrel. This equals the maximum storage area previously defined. The total area under the inflow and outflow curves should be equal since the volume of water entering and the volume of water leaving the barrel are the same. 123
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Publication No. FHWA-NHI-01-020 Sep
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Acknowledgements This document’s
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TABLE OF CONTENTS (Cont.) III. CULV
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TABLE OF CONTENTS (Cont.) F. Safety
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LIST OF FIGURES (Cont.) Figure III-
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LIST OF TABLES Table 1. Factors Inf
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ELhf ELhi ELho ELht ELO ELsf ELSO E
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GLOSSARY (Cont.) p Wetted perimeter
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B. Overview of Culverts A culvert i
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Figure I-9--Side-tapered inlet Figu
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. Partly Full (Free Surface) Flow.
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Table 1--Factors Influencing Culver
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D. Economics The hydraulic design o
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For gaged sites, statistical analys
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volume of the remaining runoff hydr
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Figure II-4--Flood hydrograph shape
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Figure II-6--Cross section location
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. Culvert Length. Important dimensi
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HYDROLOGY Peak Flow Check Flows Tab
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Figure III-1--Types of inlet contro
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Figure II-2--Flow contractions for
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The flow transition zone between th
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Figure III-6--Culvert with Inlet Su
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Condition III-7-A represents the cl
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Outlet control flow conditions can
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2 2 Vu Vd HW o + = TW + + HL (6) 2g
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This approximate method works best
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Figure III-12--Weir Crest Length De
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Critical depth is used when the tai
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4. Add the culvert flow and the roa
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NOTE: If the nomographs are put int
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Figure III-19--Critical Depth Chart
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(1) If the Manning’s n value give
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Example Problem #1 (SI Units) A cul
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Example Problem #2 (SI Units) A new
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Example Problem #3 (SI Units) Desig
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Example Problem #4 (SI Units) An ex
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CHART 51A Figure III-21--Inlet Cont
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2. Outlet Control. a. Partly Full F
Page 92 and 93: Backwater Calculations From hydraul
Page 95 and 96: English Units INLET CONTROL: AD 0.
Page 99 and 100: A. Introduction IV. TAPERED INLETS
Page 101 and 102: height by more than 10 percent (1.1
Page 103 and 104: A slope-tapered inlet has three pos
Page 105 and 106: The mitered face slope-tapered inle
Page 107 and 108: La is the approximate length of the
Page 109 and 110: E. Design Methods Figure IV-9--Tape
Page 111 and 112: a. Complete Design Data. Fill in th
Page 113 and 114: H 1 i. For FALL < D/4, use side-tap
Page 115: 3. Example Problems a. Example Prob
Page 121 and 122: . Example Problem #1 (English Units
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Page 125 and 126: 105
Page 127 and 128: c. Example Problem #2 (SI Units). F
Page 129 and 130: Conclusions: A side-tapered inlet a
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Page 133 and 134: G. Circular Pipe Culverts 1. Design
Page 135 and 136: Double barrel slope-tapered inlets
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Page 139 and 140: . Example Problem #3 (English Units
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Page 145 and 146: C. Application to Culvert Design Fi
Page 147 and 148: Figure V-6--Peak Flow Reduction Bas
Page 149 and 150: I + I + ( 2s / ∆t − O) = ( 2s /
Page 151 and 152: Table 5--Inflow Hydrograph, Example
Page 153 and 154: Figure V-10—Culvert Design Form f
Page 155 and 156: Figure V-14--Storage vs. Outflow Re
Page 157 and 158: Table 5 --Inflow Hydrograph, Exampl
Page 159 and 160: Figure V-18--Culvert Design Form fo
Page 161 and 162: Figure V-22--Storage vs. Outflow Re
Page 163 and 164: A. Introduction VI. SPECIAL CONSIDE
Page 165 and 166: With minor modifications, the culve
Page 167 and 168: If headwater and flow consideration
Page 169 and 170: Figure VI-6--Subatmospheric Pressur
Page 171 and 172: Figure VI-7--Fish Baffles in Culver
Page 173 and 174: A popular method of providing for f
Page 175 and 176: passage of the peak flow. Methods f
Page 177 and 178: Figure VI-15--Sediment Deposition i
Page 179 and 180: 1. Skewed Barrels. The alignment of
Page 181 and 182: Skewed inlets slightly reduce the h
Page 183 and 184: arrel for pipes or the flow per met
Page 185 and 186: Culvert shapes are as important in
Page 187 and 188: • Flood plain ordinances or other
Page 189 and 190: Figure VI-28--Guardrail Adjacent to
Page 191 and 192: Both of the above equations are emp
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Tables, charts, and formulas are av
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3. Endwalls and Wingwalls. Culvert
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2. Hydraulic Considerations. Long s
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conditions. Variations in the concr
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REFERENCES (www.fhwa.dot.gov/bridge
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28. "Design Approaches for Stormwat
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54. "Hydraulic Analysis of Pipe-Arc
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ADDITIONAL REFERENCES (In Alphabeti
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"Risk Analysis For Hydraulic Design
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A. Introduction APPENDIX A DESIGN M
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Chart No. 1 Shape and Material Circ
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NOTE: The rest of this Appendix A i
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Figure A-1--Dimensionless Performan
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developed for circular and elliptic
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APPENDIX B HYDRAULIC RESISTANCE OF
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D. Corrugated Metal Culverts The hy
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Curves are shown for 2-2/3 by 1/2 i
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F. Spiral Rib Pipe Spiral rib pipe
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APPENDIX C CULVERT DESIGN OPTIMIZAT
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C. Inlet Control Performance Curves
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Figure C-4--Optimization of Perform
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E. Tapered Inlet Face Control Perfo
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APPENDIX D DESIGN CHARTS, TABLES, A
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Chart Corrugated Metal Box Culverts
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Chart Circular Tapered Inlets 55A,
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Table 12--Entrance Loss Coefficient
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CHART 1B 225
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