Hydraulic Design of Highway Culverts - DOT On-Line Publications

More documents

Recommendations

Info

Figure III-12--Weir Crest Length Determinations for Roadway Overtopping It is a simple matter to calculate the flow across the roadway for a given upstream water surface elevation using Equation (8). The problem is that the roadway overflow plus the culvert flow must equal the total design flow. A trial and error process is necessary to determine the amount of the total flow passing through the culvert and the amount flowing across the roadway. Performance curves may also be superimposed for the culvert flow and the road overflow to yield an overall solution as is discussed later in this chapter. 4. Outlet Velocity. Culvert outlet velocities should be calculated to determine the need for erosion protection at the culvert exit. Culverts usually result in outlet velocities which are higher than the natural stream velocities. These outlet velocities may require flow readjustment or energy dissipation to prevent downstream erosion. In inlet control, backwater (also called drawdown) calculations may be necessary to determine the outlet velocity. These calculations begin at the culvert entrance and proceed downstream to the exit. The flow velocity is obtained from the flow and the cross-sectional area at the exit (Equation (2)). An approximation may be used to avoid backwater calculations in determining the outlet velocity for culverts operating in inlet control. The water surface profile converges toward normal depth as calculations proceed down the culvert barrel. Therefore, if the culvert is of adequate length, normal depth will exist at the culvert outlet. Even in short culverts, normal depth can be assumed and used to define the area of flow at the outlet and obtain the outlet velocity (Figure III-13). The velocity calculated in this manner may be slightly higher than the actual velocity at 40
the outlet. Normal depth in common culvert shapes may be calculated using a trial and error solution of the Manning equation. The known inputs are flow rate, barrel resistance, slope and geometry. Normal depths may also be obtained from design aids in publications such as HDS NO. 3. (23). Figure III-13--Outlet Velocity - Inlet Control In outlet control, the cross sectional area of the flow is defined by the geometry of the outlet and either critical depth, tailwater depth, or the height of the conduit (Figure III-14). Figure III-14--Outlet Velocity - Outlet Control 41
Page 1:
Publication No. FHWA-NHI-01-020 Sep
Page 4 and 5:
Acknowledgements This document’s
Page 6 and 7:
(Page intentionally blank) iv
Page 8 and 9:
TABLE OF CONTENTS (Cont.) III. CULV
Page 10 and 11: TABLE OF CONTENTS (Cont.) F. Safety
Page 12 and 13: LIST OF FIGURES (Cont.) Figure III-
Page 14 and 15: LIST OF TABLES Table 1. Factors Inf
Page 16 and 17: ELhf ELhi ELho ELht ELO ELsf ELSO E
Page 18 and 19: GLOSSARY (Cont.) p Wetted perimeter
Page 20 and 21: (Page intentionally blank) xviii
Page 22 and 23: B. Overview of Culverts A culvert i
Page 24 and 25: Figure I-9--Side-tapered inlet Figu
Page 26 and 27: . Partly Full (Free Surface) Flow.
Page 28 and 29: Table 1--Factors Influencing Culver
Page 30 and 31: D. Economics The hydraulic design o
Page 32 and 33: For gaged sites, statistical analys
Page 34 and 35: volume of the remaining runoff hydr
Page 36 and 37: Figure II-4--Flood hydrograph shape
Page 38 and 39: Figure II-6--Cross section location
Page 40 and 41: . Culvert Length. Important dimensi
Page 42 and 43: HYDROLOGY Peak Flow Check Flows Tab
Page 44 and 45: Figure III-1--Types of inlet contro
Page 46 and 47: Figure II-2--Flow contractions for
Page 48 and 49: The flow transition zone between th
Page 50 and 51: Figure III-6--Culvert with Inlet Su
Page 52 and 53: Condition III-7-A represents the cl
Page 54 and 55: Outlet control flow conditions can
Page 56 and 57: 2 2 Vu Vd HW o + = TW + + HL (6) 2g
Page 58 and 59: This approximate method works best
Page 62 and 63: Critical depth is used when the tai
Page 64 and 65: 4. Add the culvert flow and the roa
Page 66 and 67: NOTE: If the nomographs are put int
Page 68 and 69: Figure III-19--Critical Depth Chart
Page 70 and 71: (1) If the Manning’s n value give
Page 72: Example Problem #1 (SI Units) A cul
Page 80 and 81: Example Problem #2 (SI Units) A new
Page 82 and 83: Example Problem #3 (SI Units) Desig
Page 84: Example Problem #4 (SI Units) An ex
Page 88 and 89: CHART 51A Figure III-21--Inlet Cont
Page 90 and 91: 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
Page 123 and 124:
103
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
Page 131 and 132:
111
Page 133 and 134:
G. Circular Pipe Culverts 1. Design
Page 135 and 136:
Double barrel slope-tapered inlets
Page 137 and 138:
117
Page 139 and 140:
. Example Problem #3 (English Units
Page 141 and 142:
121
Page 143 and 144:
A. The Routing Concept V. STORAGE R
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
Page 193 and 194:
Tables, charts, and formulas are av
Page 195 and 196:
3. Endwalls and Wingwalls. Culvert
Page 197 and 198:
2. Hydraulic Considerations. Long s
Page 199 and 200:
conditions. Variations in the concr
Page 201 and 202:
REFERENCES (www.fhwa.dot.gov/bridge
Page 203 and 204:
28. "Design Approaches for Stormwat
Page 205 and 206:
54. "Hydraulic Analysis of Pipe-Arc
Page 207 and 208:
ADDITIONAL REFERENCES (In Alphabeti
Page 209 and 210:
"Risk Analysis For Hydraulic Design
Page 211 and 212:
A. Introduction APPENDIX A DESIGN M
Page 213 and 214:
Chart No. 1 Shape and Material Circ
Page 215 and 216:
NOTE: The rest of this Appendix A i
Page 217 and 218:
Figure A-1--Dimensionless Performan
Page 219 and 220:
developed for circular and elliptic
Page 221 and 222:
APPENDIX B HYDRAULIC RESISTANCE OF
Page 223 and 224:
D. Corrugated Metal Culverts The hy
Page 225 and 226:
Curves are shown for 2-2/3 by 1/2 i
Page 227 and 228:
F. Spiral Rib Pipe Spiral rib pipe
Page 229 and 230:
APPENDIX C CULVERT DESIGN OPTIMIZAT
Page 231 and 232:
C. Inlet Control Performance Curves
Page 233 and 234:
Figure C-4--Optimization of Perform
Page 235 and 236:
E. Tapered Inlet Face Control Perfo
Page 237 and 238:
APPENDIX D DESIGN CHARTS, TABLES, A
Page 239 and 240:
Chart Corrugated Metal Box Culverts
Page 241 and 242:
Chart Circular Tapered Inlets 55A,
Page 243 and 244:
Table 12--Entrance Loss Coefficient
Page 245 and 246:
CHART 1B 225
Page 247 and 248:
227
Page 249 and 250:
229
Page 251 and 252:
231
Page 253 and 254:
233
Page 255 and 256:
235
Page 257 and 258:
237
Page 259 and 260:
239
Page 261 and 262:
241
Page 263 and 264:
243
Page 265 and 266:
245
Page 267 and 268:
247
Page 269 and 270:
249
Page 271 and 272:
251
Page 273 and 274:
253
Page 275 and 276:
255
Page 277 and 278:
257
Page 279 and 280:
259
Page 281 and 282:
261
Page 283 and 284:
263
Page 285 and 286:
265
Page 287 and 288:
267
Page 289 and 290:
269
Page 291 and 292:
271
Page 293 and 294:
273
Page 295 and 296:
275
Page 297 and 298:
277
Page 299 and 300:
279
Page 301 and 302:
281
Page 303 and 304:
283
Page 305 and 306:
285
Page 307 and 308:
287
Page 309 and 310:
289
Page 311 and 312:
291
Page 313 and 314:
293
Page 315 and 316:
295
Page 317 and 318:
297
Page 319 and 320:
299
Page 321 and 322:
301
Page 323 and 324:
303
Page 325 and 326:
305
Page 327 and 328:
307
Page 329 and 330:
309
Page 331 and 332:
311
Page 333 and 334:
313
Page 335 and 336:
315
Page 337 and 338:
317
Page 339 and 340:
319
Page 341 and 342:
321
Page 343 and 344:
323
Page 345 and 346:
325
Page 347 and 348:
327
Page 349 and 350:
329
Page 351 and 352:
331
Page 353 and 354:
333
Page 355 and 356:
335
Page 357 and 358:
337
Page 359 and 360:
339
Page 361 and 362:
341
Page 363 and 364:
343
Page 365 and 366:
345
Page 367 and 368:
347
show all

Hydraulic Design of Highway Culverts - DOT On-Line Publications

Create successful ePaper yourself

Delete template?

Save as template?