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Chapter 31 (English measure)

1. BARREL SHAPE BOX BARREL SPAN 132 in BARRE RISE 48 in BARREL MATERIAL CONCRETE BARREL MANNING S n 0 012 INLE CONVENTIONAL INLE EDGE AND WALL 1 1 BEVEL 45 DEG FLARE INLE DEPRESSION NONE lt ENTER gt TO CONTINUE NUMBER TO EDIT ITEM 1 1 2 Prog 3 4 5 End 6 7 Edit 8 9 Dos 10 8 DATA INPUT SCREEN Figure 31 8A RREGULAR CHANNEL CROSS CROSS ON X Y COORD NO ft ft 1 12 3 194 0 2 22 3 193 0 3 28 3 192 8 4 31 0 190 4 5 43 0 190 4 6 45 7 192 8 7 51 7 193 0 8 62 0 197 6 NUMBER ED NATES lt gt D INSERT OR DELETE ENTER CONTI NUE lt P gt TO PLOT CROSS SECTI ON 1 Help 2 Prog 3 4 5 End 6 7 8 9 DOS 10 HY8 CHANNEL DATA PROMPT SCREEN Figure 31 8B IRREGULAR CHANNEL FILE 31808TW 200 0 DATE 10 10 1998 195 0 RIGHT OVERBANK n 0 08 COORDINATE LEFT OVERBANK MAIN CHANNEL 190 0 ELEVATION 185 0 8 180 0 00 10 0 20 0 30 0 40 0 50 0 60 0 COORDINATE STATION ft kn INTERPOLATED CHANNEL CROSS SECTION Figure 31 8C CULVERT FI LE EX31803 CULVERT ANALYSI S DATE 10 06 98 TAI FILE 3180 HY8 VERSI ON 6 0 CULVERT 1 1 UNI FORM F
2. 9 3130 DESIGN CRITERIA ve 10 3 00 10 313 02 Site Ciera oie E Aaa RE 10 31 3 03 Design Storm Freduency tata 12 31 3 04 Hydraulic Design 12 31 3 04 01 Allowable Headwater 12 31 3 04 02 Roadway Serviceabillty bct lapides ated 13 31 3 04 05 Maxima Velocity 13 31 3 04 04 Minimum Velocity a 14 31 3 04 05 Tailwater Relationship 14 31 3 04 06 Storage Temporary or 14 305 CulvertsSIZInS Process ua pe ete Re 14 3 3 05 0 Prior S EE 14 31 3 05 02 Pipe Culvert Interior Designation eene 15 31 3 05 03 Minimum Culvert SIze Eo 34 3 0004 COVE 31 3 05 05 Pipe Extension Structure Sizing Drocesg 31 3 05 06 Concrete Culvert Extension Sizing Process 31 3 06 Other C Ulvert EE ue 31 3 06 01 EE 31 3 06 02 Inlet or Outlet End 31 3 06 03 Pipe Length Detemmmnaton 31 3 06 04 Buoyancy Protection 31 3 06 05 Relef 31 3 06 06 Er
3. Step 14 Documentation See Chapter Twenty eight Prepare report and file with background information 31 7 0 NOMOGRAPH DESIGN The following example problem follows the Design Procedure Steps described in Section 31 6 0 1 Step 1 Assemble Site Data And Project File a Site survey project file should include the following 1 USGS site and location maps 2 3 4 5 roadway profile embankment cross section if two lane roadway ADT gt 3000 and new alignment See Figure 31 7 1 for site data b Survey notes should indicate no sediment or debris problems and no nearby structures e Studies by other agencies none d Environmental risk assessment shows the following 1 no buildings near floodplain 2 no sensitive floodplain values 3 no FEMA involvement and 4 convenient detours exist Design criteria 1 HW Maximum backwater is 1 5 in 2 RS Headwater elevation must be 2 ft below edge of pavement elevation 3 VEL Maximum velocity is 13 ft s without energy dissipator See Section 31 3 0 for INDOT criteria on outlet protection Step 2 Determine Hydrology USGS regression equations yield the following Oso 134 ft s and 148 ft s Step 3 Analyze Downstream Channel See Figure 31 7 2 for cross section of channel slope 0 001 Point Station ft Elevation ft 1 JO RU N 12 3 194 0 22 3 193 0 28 3 192 8 31 0 190 4
4. where culvert will generate excessive velocity backwater other hydraulic deficiency Length and Slope The culvert length and slope should be chosen to approximate existing topography and as practical the culvert invert should be aligned with the channel bottom and the skew angle of the stream The roadway clear zone requirements and the embankment geometry may dictate the culvert length See Chapter Forty nine Location in Plan A severe or abrupt change in channel alignment upstream or downstream is not recommended The following applies a A small culvert with no defined channel is placed normal to the roadway centerline b A large culvert perpetuating drainage in a defined channel should be skewed as necessary to minimize channel relocation and erosion utilities should be located before determining the final location of a culvert to minimize conflicts Location in Profile The culvert profile will likely approximate the natural stream profile Exceptions which must be approved by the Hydraulics Team can be considered as follows a arrest stream degradation by utilizing a drop end treatment or broken back culvert b improve hydraulic performance by utilizing a slope tapered end treatment or avoid conflicts with other utilities that are difficult to relocate such as sanitary sewers Debris Control Debris control should be designed using Hydraulic Engineering Circular No 9 Debris Con
5. 0 0 40 0 80 0 1200 16060 2000 2400 2600 2800 3200 TOTAL DISCHARGE cfs CULVERT 1 m ROADWAY INTERPOLATION TOTAL PERFORMANCE CURVE Figure 31 8N OVERTOPPI NG PERFORMANCE CURVE FOR CULVERT 1 One 144 in by 48 in RCB S HEAD I NLET OUTLET CHARGE WATER CONTROL CONTROL FLOW NORMAL CRIT OUTLET TW OUTLET TW FLOW ELEV DEPTH DEPTH TYPE DEPTH DEPTH DEPTH DEPTH VEL VEL ft3 s ft ft ft lt F4 gt ft ft ft ft ft s ft s 0 00 190 7 0 00 0 30 DN 0 00 0 00 0 00 0 00 0 00 0 00 22 2 191 7 0 73 1 03 3 0 67 0 50 1 17 1 17 1 67 1 57 44 5 192 3 1 17 1 63 3 Mt 103 0 77 1 73 1 73 2 23 1 97 66 7 192 8 1 50 2 13 3 Mt 1 37 1 00 2 20 2 20 2 67 2 27 89 9 193 2 1 83 2 57 3 Mt 167 1 23 2 57 2 57 3 00 2 47 111 2 193 6 2 13 2 90 3 Mt 193 1 43 2 87 2 87 3 67 2 70 133 4 193 9 2 43 3 23 3 Mt 2 17 1 60 3 13 3 13 3 73 2 90 148 3 194 1 2 63 3 43 3 Mt 2 33 1 73 3 30 3 30 3 93 3 00 178 0 194 5 2 97 3 87 3 Mt 2 63 1 97 3 60 3 60 4 33 3 20 200 0 194 6 3 23 3 93 3 Mt 2 87 2 10 3 63 3 63 4 80 3 23 214 0 194 7 3 40 4 00 3 Mt 3 00 2 20 3 63 3 63 5 17 3 23 El inlet face i nvert 190 7 ft El outlet invert 190 4 ft El inlet throat invert 0 00 ft El inlet crest 0 00 ft PRESS lt KEY gt TO CONTINUE VW FOR PROFI LE TABLE lt P gt TO PLOT q gt FOR I MPROVED TABLE 1 Help 2 3 4 5 End 6 7 8 9 006 10 HY8 OVERTOPPING PERFORMANCE CURVE SCREEN 144 in SPAN BY 48 in RISE CULVERT Fi
6. 0 52 1 2 2 0 86 ho the larger of TW or dc D 2 3 3 ft 0 5 Determine H from Chart 15 Outlet Control Nomograph Kg scale 0 5 Culvert length Z 300 ft n 0 012 Area 11 x 4 44 ft H 0 4 ft Elo ho 190 3 0 4 3 3 194 ft lt 194 1 ft Step 9 Determine Controlling Headwater Elevation El o 194 1 ft gt Elyc 193 5 ft The culvert is in outlet control Step 10 Calculate Outlet Velocity Vo Calculate flow depth at culvert exit Use TW if dc lt TW lt D 1 73 3 13 lt 4 TW 3 13 ft Calculate flow area 11 3 13 2 34 43 f Calculate exit velocity Vo Qso A 134 34 43 3 9 ft s Step 11 Review Results Compare alternative design with constraints and assumptions ao Check cover 199 190 7 4 1 3 3 ft therefore L 300 ft El o 194 0 ft lt AHW of 194 1 ft therefore OK Overtopping flood gt Q oo and RS Q100 Pavement edge elevation of 199 ft El o of 194 0 ft 5 ft gt 2 ft OK Outlet velocity of 3 9 ft s lt 13 3 ft s therefore OK Use revetment riprap see Section 31 3 04 03 The outlet control nomographs are designed for full flow In this example full flow does not exist because the TW depth of 3 3 ft is less than the rise of 4 ft and the culvert is on a flat slope The above answer should be considered approximate A more accurate solution is provided in Section 31 8 0 with the m
7. 3 Improved End Treatment a Should be considered for a culvert which will operate in inlet control b Can increase the hydraulic performance of the culvert but may also add to the total culvert cost Therefore it should only be used if economically justified 4 Pipe End Section Is available for either corrugated metal concrete pipe Retards embankment erosion and incurs less damage from maintenance May improve a projecting metal pipe entrance by increasing hydraulic efficiency reducing accident hazard and improving the pipe entrance s appearance Is hydraulically equivalent to a headwall but can be equivalent to a beveled or side tapered entrance if a flared enclosed transition occurs before the barrel Wingwall Is used to retain the roadway embankment to avoid a projecting culvert barrel Is used where the side slopes of the channel are unstable Is used where the culvert is skewed to the normal channel flow Provides the best hydraulic efficiency if the flare angle is between 30 and 60 Should be provided for a precast concrete drainage structure Is used to reduce scour from a high headwater depth or from approach velocity in the channel Should extend at least one pipe diameter upstream Should not protrude above the normal streambed elevation May be constructed of riprap and an appropriate geotextile or concrete Cutoff Wall Is used to prevent piping along the culvert barrel and undermining at t
8. See Section 31 10 0 for the recommended value of K Roadside safety should be considered in the selection and design See Section 49 3 0 for a detailed discussion of INDOT practices for the safety treatment of a drainage structure The following discusses the types of culvert end treatments and their advantages and disadvantages 1 Projecting Inlet or Outlet a Extends beyond the roadway embankment b Is susceptible to damage during roadway maintenance or an errant vehicle Has low construction cost d Has poor hydraulic efficiency for thin material e Should include anchoring the end treatment to strengthen the weak leading edge for a culvert of 42 in diameter or larger anchorage should include sufficient weight of concrete to resist buoyant forces see the INDOT Standard Drawings f May be strengthened by use of a concrete collar if necessary Where a projecting inlet or outlet is within the roadside clear zone the designer should consider the use of a grated box end section GBES or a safety metal end section SMES See Chapter Forty nine for INDOT criteria on roadside clear zone See the INDOT Standard Drawings for the GBES and SMES 2 Mitered End Treatment a Is hydraulically more efficient than a thin edge projecting b Should be mitered to match the fill slope Should include anchoring the end treatment to strengthen the weak leading edge for a culvert of 42 in diameter or larger
9. n Manning s n value from chart Mark point on turning line Use a straightedge and connect the size with the length Read H Use a straightedge connect Q and turning point and read H on the Head Loss scale Calculate outlet control headwater HW 1 2 3 Use Equation 31 5 14 if Vy and V are neglected as follows HW H ho SOL Equation 31 5 14 Use Equations 31 5 1 31 5 6 and 31 5 9 to include Vy and V4 If HW is less than 1 2D and the outlet controls the following apply a The barrel may flow partly full b The approximate method of using the greater of tailwater or dc D 2 may not be applicable 12 13 14 backwater calculations should be used to check the result d If the headwater depth falls below 0 75D the approximate nomograph method should not be used Step 9 Determine Controlling Headwater HWc a Compare HW and HW and use the higher value b Compare with allowable HW and adjust culvert size if necessary Step 10 Compute Discharge Over The Roadway a Choose Q and thereby establish a TW b Assume an upstream depth over the roadway HW calculate the length of roadway crest L and calculate the overtopping flow rate using Equation 31 5 15 as follows Q CaL HW Equation 31 5 15 See Section 31 5 06 e Calculate the flow in the culvert by using Equations 31 5 8 and 31 5 10 solving for V and then Qj Step 11 Calculate Outle
10. 0 5 040 194 0 194 0 43 Looks OK z ng EES al TECHNICAL FOOTNOTES 3 EL HW EL 6 ha TW or de D 2 WHICHEVER IS 1 USE Q NB FOR BOX CULVERTS INVERT OF INLET CONTROL GREATER SECTION 2 HW D HW D HW D FROM DESIGN CHARTS 7 1 ke 19 63 n D R 7 V 2g FALL HW EL EL FALL IS ZERO FOR CULVERTS ON GRADE 4 TW BASED ON DOWNSTREAM 8 EL EL H ho CONTROL OR FLOW DEPTH IN CHANNEL SUSCRIPT DEFINTIIONS COMMENTS DISCUSSION CULVERT BARREL SELECTED a Approximate f Culvert Face This is an approximate solution because size 132x48 hd Design Headwater I 1 hi Headwater in Inlet Control box not flowing full Check with er microcomputer HY8 for exact solution SHAPE i Inlet Control Section o MATERIAL Concrete n sf Streambed at Culvert Face tw Tailwater ENTRANCE Conventional Bevel CHART 17 AND PERFORMANCE CURVE FOR DESIGN EXAMPLE Figure 31 7A 190 7 199 0 STA 1 00 Sg 0 001 44 STA 4 00 SITE DATA 190 4 n 0 08 n 0 03 n 0 08 DOWNSTREAM CHANNEL SECTION NOMOGRAPH DESIGN EXAMPLE Figure 31 7A 1 FILE NAME 31833 FHWA CULVERT ANALYSIS DATE 10 12 1998 TAILWATER FILE 3180 HY8 VERSION 6 0 CULVERT NO 1 1 L CULVERT DATA SUMMARY k x kkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkkk m I
11. 0 83 1 73 1 73 2 43 66 7 192 8 1 60 2 17 3 Mt 147 1 07 2 20 2 20 2 90 89 0 193 3 1 93 2 60 3 Mt 1 77 1 30 2 57 2 57 3 27 111 2 193 7 2 27 3 03 3 Mt 207 1 50 2 87 2 87 3 70 133 5 194 0 2 57 3 37 3 Mt 2 33 1 70 3 13 3 13 4 07 148 3 194 2 2 80 3 50 3 Mt 2 50 1 83 3 30 3 30 4 27 178 0 194 6 3 17 3 87 3 Mt 2 83 2 07 3 60 3 60 4 70 200 2 194 7 3 47 4 07 3 Mt 3 07 2 23 3 63 3 63 5 27 222 5 194 9 3 73 4 20 3 Mt 3 30 2 40 3 63 3 63 5 83 El inlet face invert 190 7 ft El outlet invert 190 4 ft El inlet throat invert 0 00 ft El inlet crest 0 00 ft PRESS lt KEY gt TO CONTINUE aw FOR PROFI LE TABLE lt P gt TO PLOT d gt FOR MPROVED TABLE 1 Help 2 3 4 5 End 6 7 8 9 006 10 HY8 PERFORMANCE CURVE PROMPT SCREEN 132 in SPAN BY 48 in RISE CULVERT Figure 31 8H AED P gt 2 FILE 31807 DATE 10 10 1998 HEADWATER 195 0 ELEVATION 190 0 ft 185 0 180 0 0 0 50 0 100 0 150 0 200 0 250 0 TOTAL DISCHARGE cfs S I C ELEV m O C ELEV INTERPOLATION INLET OUTLET CONTROL HEADWATERS Figure 31 8 I PERFORMANCE CURVE FOR CULVERT 1 One 144 in by 48 in RCB S HEAD 1 OUTLET CHARGE WATER CONTROL CONTROL FLOW NORMAL OUTLET TW OUTLET FLOW ELEV DEPTH DEPTH TYPE DEPTH DEPTH DEPTH DEPTH VEL ft3 s ft ft ft lt F4 gt ft ft ft ft ft s 0 00 190 7 0 00 0 30 DN 0 00 0 00 0
12. 00 0 00 0 00 22 2 191 7 0 73 1 03 3 Mt 0 67 0 50 1 17 1 17 1 67 44 5 192 3 1 17 1 63 3 Mt 103 0 77 1 73 1 73 2 23 66 7 192 8 1 50 2 13 3 Mt 1 37 1 00 2 20 2 20 2 67 89 0 193 2 1 83 2 57 3 Mt 167 1 23 2 57 2 57 3 00 111 2 193 6 2 13 2 90 3 Mt 193 1 43 2 87 2 87 3 34 133 5 193 9 2 43 3 23 3 Mt 2 17 1 60 3 13 3 13 3 73 148 3 194 1 2 63 3 42 3 Mt 2 33 1 73 3 30 3 30 3 93 178 0 194 5 2 97 3 87 3 Mt 2 63 1 97 3 60 3 60 4 30 200 2 194 6 3 23 3 93 3 Mt 2 87 2 10 3 63 3 63 4 83 222 5 194 7 3 50 4 07 3 Mt 3 07 2 27 3 63 3 63 5 37 El inlet face invert 190 7 ft El outlet invert 190 4 ft El inlet throat invert 0 00 ft El inlet crest 0 00 ft PRESS KEY TO CONTINUE aw FOR PRCFI LE TABLE lt P gt TO PLOT d gt FOR MPROVED TABLE 1 Help 2 3 4 5 End 6 7 8 9 006 10 Figure 31 8J HY8 PERFORMANCE CURVE PROMPT SCREEN 144 in SPAN BY 48 in RISE CULVERT WUW OO SE ISIS S en PERFORMANCE CURVE FOR CULVERT 1 One 84 in OUTLET CONTROL FLOW DEPTH ft 0 30 23 97 57 07 53 93 20 73 03 63 RR WWW inlet throat invert Ve d gt D S HEAD 1 CHARGE WATER CONTROL FLOW ELEV DEPTH fts ft ft 0 00 190 7 0 00 22 2 191 9 1 03 44 5 192 6 1 67 66 7 193 2 2 17 89 0 193 7 2 67 111 2 194 2 3 13 133 5 194 6 3 57 148 3 194 9 3 87 178 0 195 4 4 47 200 2 195 7 4 90 222 5 196 3 5 37 El inlet face invert El PRESS lt KEY gt TO CONTI NUE lt P gt TO PLOT
13. 43 0 190 4 45 7 192 8 62 0 197 6 The rating curve for the channel calculated with normal depth yields the following 60 5 TW ft V ft s 44 5 1 73 1 97 89 0 3 13 2 90 133 5 2 57 2 47 148 3 3 30 3 00 178 0 3 60 3 20 Step 4 Summarize Data On Design Form See Figure 31 7 Chart 17 and Performance Curve for design example Step 5 Select Design Discharge Qa 148 ft s for HW and RS 134 ft s for outlet velocity Step 6 Perform Structure Sizing Process a Start with Trial 1 Singular Circular Pipe and proceed through the trials until the hydraulic design is complete b Review site conditions to determine what limitations may be applicable Assume shoulder PI at approximate elevation of 198 3 ft Assume pavement thickness of 0 83 ft Assume minimum cover of 1 00 ft Pipe thickness is 0 60 ft Inlet elevation is 190 7 ft Maximum allowable rise is 5 17 ft Try a circular pipe with diameter 60 in d Assume an end section which satisfies the fill slope requirement for both RCP and CMP 0 5 from Figure 31 10B Entrance Loss Coefficients Outlet Control Full or Partly Full TW 3 3 ft El 0 13 190 7 3 3 0 13 194 1 ft f With a very flat channel slope of 0 001 the culvert will likely operate under outlet control However for ease of calculations Step 7 will determine inlet control for the largest permissible pipe and if a size
14. 6 7 ft MINIMUM PIPE CULVERT SIZE Figure 31 3B PERFORM SMOOTH amp CORRUGATED HYDRAULIC CALCULATIONS IS RESULT CASE 1 CASE2 OR CASE 3 HYDRAULIC DESIGN COMPLETE GO TO TRIAL 2 LEGEND CASE 1 REQUIRED SMOOTH AND CORRUGATED PIPE SIZES ARE IDENTICAL CASE 2 REQUIRED SMOOTH AND CORRUGATED PIPE SIZES ARE DIFFERENT CASE 3 THERE IS AN ACCEPTABLE PIPE SIZE FOR ONE INTERIOR TYPE BUT NO ACCEPTABLE PIPE SIZE CAN BE FOUND FOR THE REMAINING INTERIOR TYPE CULVERTS DESIGN PROCESS Trial 1 Single Circular Pipe Figure 31 3C HYDRAULIC DESIGN COMPLETE CASE 1 CASE 2 CASE 3 PERFORM SMOOTH 8 CORRUGATED HYDRAULIC DESIGNS IS RESULT CASE 1 CASE 2 OR CASE 3 YES GO TO TRIAL 3 LEGEND REQUIRED SMOOTH AND CORRUGATED PIPE SIZES ARE IDENTICAL REQUIRED SMOOTH AND CORRUGATED PIPE SIZES ARE DIFFERENT THERE IS AN ACCEPTABLE PIPE SIZE FOR ONE INTERIOR TYPE BUT NO ACCEPTABLE PIPE SIZE CAN BE FOUND FOR THE REMAINING INTERIOR TYPE CULVERT DESIGN PROCESS Trial 2 Single Deformed Pipe Figure 31 3D SELECT SPECIFIC STRUCTURE TYPE PERFORM APPROPRIATE HYDRAULIC CALCULATIONS DOES DESIGN YIELD ACCEPTABLE STRUCTURE SIZE HYDRAULIC DESIGN COMPLETE ARE THERE ANY REMAINING SPECIALTY STRUCTURE TYPES GO TO TRIAL 4 SPECIALTY STRUCTURE TYPES ARE TO BE CONSIDERED IN FOLLOWING ORDER 1 PRECAST REINFORCED CONCRETE BOX SECTIONS 2 PRECAST REINFORCED CONCRETE THREE S
15. Screen will appear This computation table is used if overtopping is used It shows the headwater total flow rate the flow through each barrel and overtopping flow and the number of iterations it took to balance the flows The overtopping discharge of 201 ft s occurs at the roadway sag point elevation of 194 6 ft For the maximum discharge of 222 f s 215 ft s will flow through the culvert and 7 42 is will flow over the road From this information a total culvert and overtopping performance curve shown in Figure 31 8N Total Performance Curve can be obtained by selecting option P This curve is a plot of the headwater elevation vs the total flow rate which indicates how the culvert or group of culverts will perform over the selected range of discharges It is useful for comparing the effects of various combinations of culverts See Figure 31 8 O HYS Overtopping Performance Curve Prompt Screen 144 in Span by 48 in Rise 31 8 11 Review For the design criteria set forth for the example in Section 31 7 0 the design of a reinforced concrete box culvert of 144 in x 48 in is selected as follows 148 3 ft s HW 194 1 ft 194 1 ft Vo 3 93 ft s Vc 3 ft s 134 ft s Vo 3 73 ft s No energy dissipation necessary Road sag point elevation 194 6 ft Overtopping Q 201 ft s Therefore Roadway Serviceability RS gt An energy dissipater is warranted at a velocity higher than 13 3 ft s See Sec
16. analysis of culvert The FHWA Hydraulic Design of Highway Culverts HDS 45 is also acceptable HDS 45 has also been updated and released as a CD ROM the FHWA Hydraulics Library 1 HYDRAIN Microcomputer System a Is recommended by AASHTO b includes HY8 and has a User s Manual 2 HY8 FHWA Culvert Analysis Software a Is an interactive program written in Basic b Uses the theoretical basis for the nomographs c Can compute tailwater improved end treatments road overtopping hydrographs routing and multiple independent barrels d Develops and plots tailwater rating curves e Develops and plots performance curves f Is documented in the HYDRAIN User s Manual and HY8 Applications Guide 31 4 04 Modifying or Replacing an Existing Culvert If considering whether to modify or replace an existing culvert the designer should first obtain a copy of the road log from the district office The road log includes an inventory of the locations sizes and types of drainage structures located on each state highway During the field data collection process the size location and type of each culvert should be verified Each structure should be inspected See the FHWA Culvert Inspection Manual for information on structure inspection See Figure 31 4A Culvert Inspection Report Form An editable version of this form may also be found on the Department s website at www in gov dot div contracts design dmforms If necessary dist
17. analysis of culvert flow is complex due the requirements as follows ND gt gt analyzing non uniform flow with regions of both gradually varying and rapidly varying flow determining how the flow type changes as the flow rate and tailwater elevations change applying backwater and drawdown calculations energy and momentum balance applying the results of hydraulic model studies and determining if hydraulic jumps occur and if they are inside or downstream of the culvert barrel 31 5 02 Approach The procedure considers the following Control Section The control section is the location where there is a unique relationship between the flow rate and the upstream water surface elevation Inlet control is governed by the inlet geometry Outlet control is governed by a combination of the culvert end treatment geometry the barrel characteristics and the tailwater Minimum Performance Minimum performance is assumed by analyzing both inlet and outlet control and using the highest headwater The culvert may operate more efficiently at times more flow for a given headwater level but it will not operate at a lower level of performance than calculated 3 Culvert Sizing The culvert sizing process must satisfy the criteria as follows a allowable headwater elevation at Q oo b roadway serviceability for storm of specific magnitude depending on functional classification and maximum pip
18. has GA 56 LIST OF FIGURES Figure Title 31 1A Maximum Span Lengths for Culverts 31 1B Culvert Symbols 31 3A Design Storm Frequency Culverts 31 3B_Minimum Pipe Sizes Culverts 31 3C Culvert Design Process Trial 1 Single Circular Pipe 31 30 Culvert Design Process Trial 2 Single Deformed Pipe 31 3E Culvert Design Process Trial 3 Single Specialty Structure 31 3F Culvert Design Process Trial 4 Multiple Circular Pipes 31 3G Culvert Design Process Trial 5 Multiple Deformed Pipes 31 3H_ Culvert Design Process Trial 6 Multiple Specialty Structures 31 4A Editable Culvert Inspection Report 31 5A Unsubmerged Submerged and Transition 31 5B Flow 31 5C Flow Type V 31 5D Flow Type IV 31 5E Flow Type VI 31 5F Flow Type VII 31 5G Flow Type II TW dc 31 5H Flow Type III TW gt dc 31 5 I Overall Performance Curve 31 7 1 Nomograph Design Example Site Data 31 7 2 Nomograph Design Example Downstream Channel Section 31 7A Chart 17 and Performance Curve for Design Example 31 8 HYS Data Input Prompt Screen 31 8B HYS Channel Data Prompt Screen 31 8C Channel Cross Section 31 8D HYS Rating Curve Prompt Screen 31 8E Tailwater vs Flow Rate 31 8F Roadway Profile 31 8G HYS Data Summary Prompt Screen 31 8H HYS Performance Curve Prompt Screen 132 in x 48 in 31 8 I Inlet Outlet Control Headwaters 31 8J HYS Performance Curve Prompt Screen 144 in x 48 in 31 8K HYS Performance Curve Prompt S
19. is too small Step 7 will indicate continuing on to the next trial 7 Step 7 Determine Inlet Control Headwater Depth HW Use inlet control nomograph 8 D 5 ft Kz 0 5 Q 148 ft s From nomograph HW D 1 16 HW 1 16 5 5 8 ft El HW El 5 8 190 7 196 5 ft gt 194 1 ft therefore No Good Go to Trial 2 Single Deformed Pipe Maximum rise 60 in Maximum allowable corrugated metal pipe arch size 72 in x 48 in From nomograph HW D 1 55 HW 1 55 4 6 2 ft 6 2 190 7 196 9 ft gt 194 1 ft therefore No Good Try reinforced concrete deformed pipe 100 in x 63 in From nomograph HW D 0 75 HW 0 75 5 27 3 95 El 3 95 190 7 194 7 ft gt 194 1 ft therefore No Good Go to Trial 3 Single Specialty Structure With a maximum of a 1 5 in increase in backwater allowed and a flat slope of 0 001 a wide shallow box will be necessary Therefore try a reinforced concrete box 132 in x 48 in with a wingwall 30 deg to 75 deg to barrel Kg 0 5 from Figure 31 10B Use inlet control nomograph D 4ft 148 3 11 13 48 ft s per foot HWID 0 71 HW 0 71 4 2 84 ft El 190 7 2 84 193 54 ft lt 194 1 ft therefore 8 10 11 Go to outlet control Step 8 Determine Outlet Control Headwater Depth at Inlet HW TW 3 3 ft for Q 148 3 ft s dc 1 73 ft from Critical Depth Rectangular Section chart dc D 2
20. outlet protection to prevent erosion The protection used must be in accordance with the following 1 Revetment riprap is required for a structure with an outlet velocity V of 6 5 ft s or lower 25 Class I riprap is required for a structure with 6 5 ft s lt V lt 10 ft s 3 Class 2 riprap is required for a structure with 10 ft s lt V lt 13 ft s 4 An energy dissipator is required if V gt 13 ft s See Chapter Thirty four for the design of an energy dissipator If clear zone or other issues prohibit the use of the required riprap gradation the designer must contact the Hydraulics Team for additional instructions 31 3 04 04 Minimum Velocity The minimum velocity in the culvert barrel should result in a tractive force ydS greater than critical of the transported streambed material at a low flow rate The designer should use 3 ft s if the streambed material size is not known 31 3 04 05 Tailwater Relationship For a channel the designer should consider the following 1 Evaluate the hydraulic conditions of the downstream channel to determine a tailwater depth see Chapter Thirty gt Calculate backwater curves for sensitive locations or use a single cross section analysis 3 Use the critical depth and equivalent hydraulic grade line if the culvert outlet 15 operating with a free outfall 4 Use the headwater elevation of a nearby downstream culvert if it is above the channel depth For a confluence
21. square cut end Corrugated Metal Pipe m Anchor Projecting from fill Corrugated Metal Pipe Metal Pipe End Section end section conforming 0 to fill slope Section conforming to fill slope Corrugated Metal Pipe Safety Metal End Section mitered to conform 0 to fill slope Corrugated Metal Pipe 0 0 Safety Metal End Section end section conforming to fill slope Corrugated Metal Pipe Safety Metal End Section mitered to conform to fill slope Corrugated Metal Pipe Safety Metal End Section end section conforming 0 to fill slope Single Pipe Concrete pco ege projecting from fill Single Pipe Concrete from fill square cut end 5 5 7 5 7 5 Single Pipe Concrete 2 projecting from fill Multiple Pipe Concrete from fill square cut end Multiple Pipe Concrete a projecting from fill ENTRANCE LOSS COEFFICIENT Kz FOR STANDARD INDOT CULVERT Figure 31 10C N a ER CULVERT DESIGN FORM PROJECT DESCRIPTION SHEET DESIGNER DATE REVIEWER DATE HYDROLOGICAL DATA METHOD DRAINAGE AREA m STREAM SLOPE CHANNEL SHAPE E See Figure 31 10D 1 for culvert design details DESIGN FLOWS TAILWATER years FLOW 3 5 TW ft FLOW HEADWATER CALCULATIONS PER INLET CONTROL OUTLET CONTROL OUTL CULVERT DESCRIPTION BAR Veto COMMENTS MATERIAL SHAPE SIZE ENTRANCE REL FALL EL TW TECHNICAL FOOTNOTES 1 USE Q NB FOR BOX CULVERT 6 h TW or 4
22. than critical depth but below the top of the barrel 3 The total barrel area 15 used where the tailwater exceeds the top of the barrel 31 5 06 Roadway Overtopping A roadway is designed to avoid overtopping during the appropriate design storm given for the road serviceability requirement However for a storm that exceeds the road serviceability design storm it is necessary to calculate HW elevations and velocities Roadway overtopping will begin once the headwater rises to the elevation of the roadway The overtopping will occur at the low point of a sag vertical curve on the roadway The flow will be similar to flow over a broad crested weir Flow coefficients for flow overtopping a roadway embankment are shown in HDS 41 Hydraulics of Bridge Waterways and in the documentation of HY 7 Bridge Waterways Analysis Model Equation 31 5 12 defines roadway overtopping as follows Q CLHW gt Equation 31 5 12 Where overtopping flow rate ft s Ca overtopping discharge coefficient weir coefficient KC k submergence coefficient discharge coefficient L length of the roadway crest ft HW the upstream depth measured above the roadway crest ft The length is difficult to determine where the crest is defined by a roadway sag vertical curve Either of the following may be used l Subdivide the length into a series of segments The flow over each segment is calculated for a given headwater The flows for each se
23. 1 Help 2 3 lt F4 gt ft 0 NF 190 7 ft 0 00 ft PPP RWUNNAIS EO 00 00 60 10 60 NORMAL CRI T TYPE DEPTH DEPTH DEPTH FOR PROFI LE TABLE FOR I MPROVED I TABLE 4 Type 5 End 6 by 48 in RCB OUTLET TW OUTLET DEPTH VEL ft ft ft ft s 0 00 0 00 0 00 0 00 0 70 1 17 1 17 2 87 1 10 1 73 1 73 3 83 1 47 2 20 2 20 4 57 1 77 2 57 2 57 5 15 2 03 2 87 2 87 5 80 2 30 3 13 3 13 6 37 2 47 3 30 3 30 6 70 2 80 3 60 3 60 7 40 3 03 3 63 3 63 8 27 3 23 3 63 3 63 9 20 El outlet invert 190 4 ft El inlet crest 0 00 ft 7 8 9 006 10 84 in SPAN BY 48 in RISE CULVERT Figure 31 8K HY8 PERFORMANCE CURVE PROMPT SCREEN WUW 0 td CULVERT FI LE HDS5EX1 DATE 10 10 1998 TAI FILE AP GDEX1 CULVERT NO 1 OF 1 CULVERT ANALYSI S HY 8 VERSI ON 6 0 SUMMARY TABLE FOR FI LE 2400 lt gt SITE DATA lt C gt CULVERT SHAPE MATERI AL INLET OUTLET CULVERT BARRELS NO ID pM FARE SHAPE FER LE MATERI AL in in 1 55 7 eg 1 RCB her 012 ONVENTI 2 3 4 5 6 HEADMATER ELEVATI ON f ENTER ALLOWABLE ue 0 CONTROLLI NG 194 9 CONTROL 194 5 OUTLET CONTROL 194 9 FLOW VELOCI TY ft s V CULVERT 6 73 V CHANNEL 3 00 Q ft3 s 148 3 SLOPE 0 0010 FLOW DEPTHS ft CULVERT 3 30 CHANNEL 3 30 NORMAL 400 CRI TI CAL 2 47 MAXI MJM lt ENTER gt TO RETU
24. 13 TECHNICAL FOOTNOTES 9 If 8 gt 7 Adj L 0 5 B E NB Taper L SELECTED DESIGN 1 Slope Tapered EL Face Invert EL Stream Bed at Face 1 B Side Tapered EL Face Invert EL Throat Invert 1 ft approx u 2 3 Li 2 HW EL EL Face Invert EE 0 5 NB 2 3 110 gt gt 0 4 From Design Charts 11 Slope Tapered Li La Ls Bevels Angle 5 Min Br Q Side Tapered L 0 5 B NB b 6 Min Ls 0 5NB 12 HW EL EL Crest Invert 7 L2 S EL Face Invert EL Throat Invert 0 6340 Taper 1V 8 Check L 0 5 B NB aper L er S W SYMMETRICAL WINGWALL FLARE ANGLES FROM 15 TO 90 Y TAPER SIDE TAPERED END TREATMENT Figure 31 10E 1 SYMMETRICAL WINGWALL FLARE ANGLES FROM 15 90 r 2 T m BEVEL OPTIONAL FACE SECTION BEND SECTION THROAT SECTION SLOPE TAPERED END TREATMENT Figure 31 10E 2 RO DES NO STATION CULVERT DESIGN FORM MITERED INLET o 3 DESIGNER DATE PROJECT DESCRIPTION SHEET OF REVNER DATE DESIGN DATA COMMENTS Q ft s ft EL Throat Invert ft EL Stream Bed at Face ft FALL ft TAPER 1 4H 1V to 6H 1V STREAM SLOPE S fft SLOPE OF BARREL S 5 1 2H 1V to 3H 1V B
25. 3 Mark the first HW D scale Extend a horizontal line to the desired scale read HW D and identify on Chart in Section 31 10 0 d Calculate headwater depth HWi 1 Multiply HW D by D to obtain HW to energy gradeline 2 Neglecting the approach velocity HWi HW 3 Including the approach velocity HWi HW approach velocity head Step 8 Determine Outlet Control Headwater Depth At Inlet HW a Calculate the tailwater depth TW using the design flow rate and normal depth single section or using a water surface profile b Calculate critical depth dc using the appropriate chart in HDS 5 1 Locate flow rate and read dc 2 dc cannot exceed D 3 If dc 0 9D consult Handbook of Hydraulics King and Brater for a more accurate dc if needed because curves are truncated where they converge Calculate dc D 2 d Determine ho It equals the larger of TW or dc D 2 Determine entrance loss coefficient from Section 31 10 0 Determine losses through the culvert barrel H 1 2 3 4 5 Use nomograph FHWA Hydraulics Library CD or Equation 31 5 8 or 31 5 9 if outside the range Locate appropriate scale Locate culvert length L or 1 Use L if Manning s n matches that of the culvert Use L to adjust for a different culvert value L Equation 31 5 13 Where L adjusted culvert length ft L actual culvert length ft desired Manning s n value
26. 8 I Inlet Outlet Control Headwaters plot can be obtained by entering P In this example the culvert is operating in outlet control the upper curve throughout the discharge range Backwater should be calculated as follows BW Headwater El Inlet El Tailwater Depth For this example BW at Q 148 3 ft s is 194 2 190 7 3 3 202 ft The backwater for the 132 in x 48 in culvert is greater than allowable for 1 5 in The next larger size of 144 in x 48 in will be analyzed 31 8 07 Performance Curve for Culvert Size of 144 in x 48 in Because the design headwater criterion was not satisfied by a size of 132 in x 48 in try a size of 144 in x 48 in and modify the file accordingly The resulting performance table shown as Figure 31 8 indicates that the design headwater will not be exceeded at 148 3 ft s The designer must check the roadway serviceability at Q oo and the maximum velocity at Qo This structure is sized to satisfy the INDOT criteria on new alignment of increase of 1 5 in maximum backwater if compared to existing conditions If the culvert had been a replacement structure the INDOT criteria is a maximum total backwater of 12 in The box culvert size can be modified to satisfy this criterion 31 8 08 Performance Curve for Culvert Size of 84 in x 48 in The user can modify the existing program file to analyze a smaller barrel Try a size of 84 in x 48 in From the Culvert Program Options Menu press E to e
27. D 2 WHICHEVER IS GREATER 2 HW D HW D OR HW D FROM DESIGN CHARTS V 19 63n L 3 FALL HW Elna FALL IS ZERO FOR CULVERT ON GRADE 7 H l k ELn EL 2g 8 Re 4 INVERT OF INLET CONTROL SECTION 8 El EL H h SUSCRIPT DEFINTIIONS COMMENTS DISCUSSION Approximate Culvert Face Design Headwater Headwater in Inlet Control Headwater in Outlet Control Inlet Control Section Outlet 5 Streambed at Culvert Face TW Tailwater CULVERT BARREL SELECTED SIZE SHAPE MATERIAL ENTRANCE ROADWAY ELEVATION ft ELH ft ft ft ft CULVERT DESIGN DETAILS Conventional End Treatment Figure 31 10D 1 RO DES NO STATION CULVERT DESIGN FORM TAPERED INLET DESIGNER DATE PROJECT DESCRIPTION SHEET OF REVIEWER DATE DESIGN DATA COMMENTS Q ft s ft EL Throat Invert ft EL Stream Bed at Face ft FALL ft TAPER 1 4H 1V to 6H 1V STREAM SLOPE Sc ft ft SLOPE OF BARREL ft ft 5 1 2H 1V to 3H 1V Barrel Shape and Material N B D Inlet Edge Description EL SLOPE TAPERED ONLY SIDE TAPERED w FALL EL Face HW Q_ Min Sel Min Check Adj Adj EL Min Q Throat Invert HW E Br Br Ected La 2 Le Li Crest HWe W ft s EL Invert 1 2 3 4 5 Br 6 7 8 9 10 11 Invert 12
28. E BUT NO ACCEPTABLE PIPE SIZE CAN BE FOUND FOR THE REMAINING INTERIOR TYPE CULVERT DESIGN PROCESS Trial 5 Multiple Deformed Pipes Figure 31 3G REFER FIGURE 31 3E FOR ORDER WHICH SELECT SPECIFIC STRUCTURE TYPE SPECIALTY STRUCTURE TYPES MUST BE CONSIDERED CONSIDER TWIN STRUCTURE INSTALLATION PERFORM SMOOTH amp CORRUGATED HYDRAULIC CALCULATIONS DOES DESIGN YEILD ACCEPTABLE STRUCTURE SIZE HYDRAULIC DESIGN COMPLETE ARE THERE OTHER AVAILABLE SPECIALTY ND STRUCTURE TYPES SELECT SPECIFIC STRUCTURE TYPE CONSIDER TRIPLE STRUCTURE INSTALLATION PERFORM APPROPRIATE HYDRAULIC CALCULATIONS DOES DESIGN YEILD ACCEPTABLE STRUCTURE SIZE HYDRAULIC DESIGN COMPLETE ARE THERE NO OTHER AVAILABLE STRUCTURE TYPES CONTACT HYDRAULICS UNIT CULVERT DESIGN PROCESS Trial 6 Multiple Specialty Pipes Figure 31 3H CULVERT INSPECTION REPORT ROUTE R P DISTRICT INVENTORY DATA NO LANES CLEARANCE FILL DESCRIPTION CULVERT NO route co no r p ROADWAY ITEMS RATING COMMENTS ALIGNMENT PAVEMENT SHOULDERS EMBANKMENT OVERALL CULVERT ITEMS RATING COMMENTS HEADWALLS WINGWALLS BARREL BOX SETTLEMENT OVERALL CHANNEL ITEMS RATING COMMENTS ALIGNMENT EROSION SCOUR DRIFT SEDMT ADEQUACY OVERALL OVERALL RATING MX NEEDED INSTIP CODE INSTIP Codes 0 No Work Needed 1 Replace Structure by Contract 2 Repair Structure
29. IDED CULVERT 3 STRUCTURAL PLATE ARCH 4 OTHER STRUCTURE TYPE APPROVED BY HYDRAULICS UNIT CULVERT DESIGN PROCESS Trial 3 Single Specialty Structure Figure 31 3E GONSIDER TWO PIPE INSTALLATION PERFORM SMOOTH 8 CORRUGATED HYDRAULIC CALCULATIONS IS RESULT CASE 1 CASE 2 OR CASE 3 YES NO HYDRAULIC DESIGN COMPLETE CONSIDER INSTALLATION PERFORM SMOOTH 8 CORRUGATED HYDRAULIC CALCULATIONS IS RESULT CASE 1 CASE 2 NO OR CASE 3 HYDRAULIC DESIGN COMPLETE GO TO TRIAL 5 LEGEND CASE 1 REQUIRED SMOOTH AND CORRUGATED PIPE SIZES ARE IDENTICAL CASE 2 REQUIRED SMOOTH AND CORRUGATED PIPE SIZES ARE DIFFERENT CASE 3 THERE IS AN ACCEPTABLE PIPE SIZE FOR ONE INTERIOR TYPE BUT NO ACCEPTABLE PIPE SIZE CAN BE FOUND FOR THE REMAINING INTERIOR TYPE CULVERT DESIGN PROCESS Trial 4 Multiple Circular Pipes Figure 31 3F CONSIDER TWO PIPE INSTALLATION PERFORM SMOOTH 8 CORRUGATED HYDRAULIC CALCULATIONS IS RESULT CASE 1 CASE2 OR CASE 3 YES NO CONSIDER THREE PIPE HYDRAULIC DESIGN COMPLETE INSTALLATION PERFORM SMOOTH amp CORRUGATED HYDRAULIC CALCULATIONS IS RESULT CASE 1 CASE2 OR CASE 3 YES NO HYDRAULIC DESIGN COMPLETE GO TO TRIAL 6 LEGEND CASE 1 REQUIRED SMOOTH AND CORRUGATED PIPE SIZES ARE IDENTICAL CASE 2 REQUIRED SMOOTH AND CORRUGATED PIPE SIZES ARE DIFFERENT CASE 3 THERE IS AN ACCEPTABLE PIPE SIZE FOR ONE INTERIOR TYP
30. ION 6 0 EE SITE DATA CULVERT SHAPE MATERIAL INLET CULV I NLET OUTLET CULVERT BARRELS N ELEV ELEV LENGTH SHAPE SPAN RISE MANNI NG NLET ft ft ft MATERIAL in in n TAPE m 1 190 7 190 4 300 1 RCB 132 0 012 CONVENTI ONAL 2 3 4 5 6 OPTION MENU PRESS lt LETTER gt CULVERT FILE SINGLE CULVERT NO OVERTOPPI NG lt gt Create S Calculate E Edit M Minimize Width N Name lt R gt Report Display or Print D Directory lt F gt File Save PC and LST files AVAILABLE FILES MULTIPLE CULVERTS amp OVERTOPPING Cul vert EX31803 NP 0 Overtoppi ng Out put EX31803 PC R Report Display or Print Report None L List Save PC and LST files DESI GN OPTI ONS DEFAULT OPTI ONS H Hydrograph U Units Used English Routing W Outlet Control Profiles lt gt 01551 pator lt P gt Paths for files 6 Defaults lt Enter gt for Documentation Menu lt Q gt Quit 1 Help 2 Progr 3 4 5 End 6 1 8 9 005 10 HY8 DATA SUMMARY PROMPT SCREEN Figure 31 8G WUW 9 ISIS FEE E O PERFORMANCE CURVE FOR CULVERT 1 One 132 in by 48 in RCB S HEAD 1 OUTLET CHARGE WATER CONTROL CONTROL FLOW NORMAL OUTLET TW OUTLET FLOW ELEV DEPTH DEPTH TYPE DEPTH DEPTH DEPTH DEPTH VEL ft s ft ft ft lt F4 gt ft ft ft ft ft s 0 00 190 7 0 00 0 30 DN 0 00 0 00 0 00 0 00 0 00 22 2 191 7 0 77 1 03 3 Mt 0 70 0 53 1 17 1 17 1 83 44 5 192 3 1 23 1 67 3 Mt 1 13
31. LOW RATI NG CURVE FOR DOWNSTREAM CHANNEL FLOW WS E FROUDE DEPTH VEL SHEAR ft s ft NUMBER ft ft s lb ft 0 00 190 4 0 000 0 00 0 00 0 00 22 2 191 5 0 267 1 17 1 57 0 06 44 5 192 1 0 280 1 73 1 97 0 09 66 7 192 6 0 287 2 20 2 27 0 11 89 0 192 9 0 293 2 57 2 47 0 12 111 2 193 2 0 299 2 86 2 70 0 14 133 5 193 5 0 304 3 13 2 90 0 15 148 3 193 7 0 307 3 30 3 00 0 16 178 0 194 0 0 312 3 60 3 20 0 18 200 2 194 0 0 312 3 63 3 23 0 18 222 5 194 0 0 312 3 63 3 23 0 18 Note Shear stress was calcul ated usi ng R PRESS lt D gt FOR DATA lt P gt PLOT NG CURVE lt ESC gt FOR CHANNEL SHAPE MENU lt ENTER gt TO CONTI NUE 1 Help 2 Progr 3 4 5 End 6 7 8 9 DOS 10 8 RATING CURVE PROMPT SCREEN Figure 31 8D DOWNSTREAM CHANNEL RATING CURVE FILE 31807 DATE 10 10 1998 WATER 195 0 SURFACE 190 0 ELEVATION ft 185 0 180 0 0 0 50 0 100 0 150 0 200 0 250 0 DISCHARGE cfs O DATA 002002 mska INTERPOLATED TAILWATER VS FLOWRATE Figure 31 8E OVERTOPPING PROFILE FILE 31807 200 0 DATE 10 10 1998 COORDINATE 195 0 ELEVATION 190 0 ft 185 0 180 0 0 0 200 0 400 0 600 0 800 0 1000 0 COORDINATE STATION ft DATA INTERPOLATED ROADWAY PROFILE Figure 31 8F CURRENT DATE 10 12 1998 FILE DATE 10 12 1998 CURRENT TIME 11 34 41 FILE NAME 31833 FHWA CULVERT ANALYSIS V 8 VERS
32. OT will not INDOT policy for a culvert replacement or rehabilitation is that the surcharge created by a proposed structure must be equal to or less than the existing surcharge unless the existing surcharge is less than 1 ft This will allow future widening of the structure If the surcharge created by an existing structure is greater than 1 ft the proposed surcharge for the culvert replacement or extension must not be greater than 1 ft above the natural channel flood profile 3 Right of Way The ponding limit from the AHW cannot exceed the right of way limit for a structure on a new alignment 4 Upstream Channel The ponding limit from the AHW cannot exceed the banks of an upstream channel for a structure on a new alignment 5 Other Other constraints AHW include the following a grades of adjacent drives b finished floor elevation of adjacent buildings or other improvements and elevation of existing cropland or other property 31 3 04 02 Roadway Serviceability For the appropriate design storm headwater caused by the proposed structure cannot exceed the following for the roadway 1 If is the appropriate design storm the resulting headwater elevation must be at least 2 ft below the edge of pavement elevation 2 If the appropriate design storm frequency is less than resulting headwater elevation must not exceed the edge of pavement elevation 31 3 04 03 Maximum Velocity Each culvert requires
33. OX CULVERT X Y X LESS THAN 20 ft AT GRADE OR UNDER FILL ONE OR MULTI SPAN p Y m Y LESS THAN 20 ft METAL PIPE UNDER FILL ONE OR MULTI SPAN MAXIMUM SPAN LENGTHS FOR CULVERTS Figure 31 1A Area of cross section of flow Allowable headwater Barrel width fi fi in or ft fi Culvert diameter or barrel height in or ft Depth of flow f Critical depth of flow fi Acceleration due to gravity ft s ft s ft ft A AHW BW d dc H fi H fi fi f fi Ho fi Hy f ho f HW fi L fi n 2 t t t t t t t t t t t t t t t Rate of discharge ft ft TW V Va Vo Vu Y t CULVERT EQUATION SYMBOLS Figure 31 1B Functional Allowable Roadway Allowable Classification Backwater Serviceability Velocity S Non Freeway gt 4 Lanes Qw Qu Two Lane Facility AADT gt 3000 Q100 lt 3000 gt AADT gt 1000 Q100 AADT lt 1000 Note The design storm frequency for a culvert extension structure is identical to that for a new culvert structure Traffic volume is for a 20 year projection DESIGN STORM FREQUENCY CULVERT Figure 31 3A Structure Minimum Circular Minimum Deformed Application Pipe Size Pipe Area Drive m in 1 or Public Road 15 in 1 1 ft Approach 2 lanes Mainline or Public Road Approach gt 3 Lanes 36 in
34. RN lt H gt TO CHANGE 5 TO SAVE FILE 1 2 3 4 5 End 6 7 8 9 10 8 MINIMIZATION ROUTINE TABLE PROMPT SCREEN Figure 31 81 HY8 VERSION 6 0 SUMMARY OF CULVERT FLOWS ft3 s FILE 31808 DATE 10 12 1998 ELEV ft TOTAL 1 2 3 4 5 6 ROADWAY TER 190 7 0 0 0 0 0 00 0 00 0 00 0 00 0 00 0 00 1 191 7 21 2 21 2 0 00 0 00 0 00 0 00 0 00 0 00 1 102 3 45 9 45 9 0 00 0 00 0 00 0 00 0 00 0 00 1 192 8 67 1 67 1 0 00 0 00 0 00 0 00 0 00 0 00 1 193 2 88 3 88 3 0 00 0 00 0 00 0 00 0 00 0 00 1 193 6 113 0 109 5 0 00 0 00 0 00 0 00 0 00 0 00 1 193 9 134 2 134 2 0 00 0 00 0 00 0 00 0 00 0 00 1 194 1 148 3 148 3 0 00 0 00 0 00 0 00 0 00 0 00 1 194 5 176 6 176 6 0 00 0 00 0 00 0 00 0 00 0 00 1 194 6 201 3 201 3 0 00 0 00 0 00 0 00 0 00 0 00 4 194 7 222 5 215 4 0 00 0 00 0 00 0 00 0 00 7 42 6 194 6 201 3 201 3 0 00 0 00 0 00 0 00 0 00 OVERTOPPI NG PRESS lt P gt TO PLOT TOTAL RATING CURVE lt T gt TO DISPLAY TABLE FOR EACH CULVERT E TO DISPLAY ERROR TABLE R TO PRI NT REPORT Output stored in HDS5EX1 PC H TO RETURN TO HEADWATER TABLE ENTER TO RETURN TO OPTION MENU 1 Help 2 Progr 3 Ti me 4 5 End 6 1 8 9 005 10 HY8 SUMMARY OF CULVERT FLOWS PROMPT SCREEN Figure 31 8 om n n en ep HEADWATER M n Wl 195 0 EHE Jor AN ELEVATION Le 190 0 gt ft 185 0 1800
35. TABLE OF CONTENTS TABLE OF CONTENTS A wk olka GE A 1 LIST OF ULE Ud ce 3 31 L Maximum Span Lengths for Culvetrts 5 SE E e 5 31 3 Design Storm Frequency Culverts nus 5 31 3B Minimum Pipe Sizes Culverts ET 5 31 3C Culvert Design Process Trial 1 Single Circular Pipe 3 31 3D Culvert Design Process Trial 2 Single Deformed Pipe 5 31 3E Culvert Design Process Trial 3 Single Specialty Structure 5 31 3F Culvert Design Process Trial 4 Multiple Circular Pipes 3 31 3G Culvert Design Process Trial 5 Multiple Deformed Pipes 3 31 3H Culvert Design Process Trial 6 Multiple Specialty Structures 5 31 4A Editable Culvert Inspection Report 5 31 5 Unsubmerged Submerged and 5 SB Elow Type Kos doco dO EEEE GA 5 31 5C BLOW Typ V E 5 FLISER 5 31 5E Flow Type VI uuu 5 JSF u uu a 5 35G F w Type H gt dex aca 5 31 A Flow Type M TW gt de 5 31 5 L Overall P
36. Trial 1 Single Circular Pipe 3 3D Culvert Design Process Trial 2 Single Deformed Pipe 31 3E Culvert Design Process Trial 3 Single Specialty Structure 31 3F Culvert Design Process Trial 4 Multiple Circular Pipes 31 3G Culvert Design Process Trial 5 Multiple Deformed Pipes 31 3H Culvert Design Process Trial 6 Multiple Specialty Structures 31 3 05 02 Pipe Culvert Interior Designation During the performance of Trials 1 2 4 or 5 specific pipe materials will not be considered Instead two generic designs are required One design will size pipes with smooth interiors and the second will size pipes with corrugated interiors The smooth interior hydraulic design will be based on a Manning s n value of 0 012 and can use the nomographs or computer software used for sizing a reinforced concrete pipe The corrugated hydraulic design is based on a Manning s n value of 0 024 and can utilize the nomographs or computer software used to size a corrugated metal pipe If the corrugated pipe design indicates that structural plate pipe is required the Manning s n value must be in accordance with accepted engineering practice See Figure 31 10A for typical values nomographs or computer software used to size a structural plate pipe may be used to determine the required size for a larger structure The two hydraulic designs for an individual structure will be based on identical pipe lengths and invert elevations If separate hydrauli
37. VATION ft a CULVERT PLUS ROADWAY OVERTOPPING ROADWAY CREST INLET CULVERT OUTLET CONTROL TOP OF GULVERT Ld A OVERALL PERFORMANCE CURVE FLOW RATE ft 9s OVERALL PERFORMANCE CURVE Figure 31 51 199 0 190 7 190 4 So 000184 STA 1 00 STA 4 00 NOMOGRAPH DESIGN EXAMPLE SITE DATA Figure 31 7 1 n 0 08 0 03 0 08 4 5 NOMOGRAPH DESIGN EXAMPLE DOWNSTREAM CHANNEL SECTION Figure 31 7 2 STATION CULVERT DESIGN FORM DESIGNER DATE PROJECT Example Problem Nomograph SHEET REVIEWER DATE HYDROLOGICAL DATA METHOD USGS DRAINAGE AREA TREAM SLOPE ANNET SHAPE pi Dese See Figure 31 7A 1 for Details ROUTING D OTHER L SHEETS DESIGN FLOWS TAILWATER R I YEARS FLOW ft s _ 133 148 3 SEE ADD HEADWATER CALCULATIONS CULVERT DESCRIPTION MATERIAL SHAPE SIZE ENTRANCE HW D FALL Ebm TW 4 H ELno 2 3 4 5 6 7 8 5 CONTROL HEADWATER ELEVATION OUTLET VELOCITY Trial 1 Single or 60 inch 1483 1483 1 16 580 11965 No God Case Trial 2 Single Deformed Conc 100 63 148 3 1483 0 75 397 1947 God Case4 Trial 2 Single CSP A 72 x48 1483 1483 155 620 11969 Good Cae4 Trial3 RCB132 x48 7 11483 1483 071 1935 173 287 33
38. a lower headwater backwater calculations are required See Figure 31 5G if TW lt dc or Figure 31 5H if TW gt dc 31 5 05 Outlet Velocity Culvert outlet velocity should be calculated to determine the extent of erosion protection required at the culvert exit A culvert affects an outlet velocity which is higher than the natural stream velocity See Section 31 3 0 for the INDOT policy on outlet protection 31 5 05 01 Inlet Control The velocity is calculated from Equation 31 5 2 after determining the outlet depth Either of the following methods may be used to determine the outlet depth 1 Calculate the water surface profile through the culvert Begin the computation at dc at the entrance and proceed downstream to the exit Determine the depth and flow area at the exit 2 Assume normal depth and velocity This approximation may be used because the water surface profile converges towards normal depth if the culvert is of adequate length This outlet velocity may be slightly higher than the actual velocity at the outlet Normal depth may be obtained from design aids described in publications such as HDS 43 31 5 05 02 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 The following applies 1 Critical depth is used where the tailwater is less than critical depth 2 Tailwater depth is used where tailwater is greater
39. arrel Shape and Material N B D Inlet Edge Description EL Q EL Face HW Sel Min Check Adj Adj EL Min Throat y Invert HW E ected La L2 L2 Li Crest HWc W W s Invert 1 2 3 4 5 6 Bi 7 8 9 10 11 12 13 Inv 14 15 16 TECHNICAL FOOTNOTES 11 If 10 gt 9 Adj L 0 5 NB Taper L mak DESIGN f 1 Is 12 If 9 gt 10 Adj ae z Du 5 18 1 0 5 B NB Le 2 EL Face Invert EL Stream Bed at Crest y 13 Li L2 La La 7 3 HW EL n EL Face Invert 411D2E2D 14 HW EL EL Crest Invert Bevels 5 From Design Charts 6 Min Bi Q 0 8 0 6340 7 Min Ls 0 5NB 8 L ySi D S 15 Min W d 9 Le S EL Crest Invert EL Throat Invert HW Tar _ 4V If negative do not use mitered inlet 21 a EP AV et 1 f E 10 Check L 0 5 B NB Taper L 16 W NB E If W lt Min W adjust taper FACE SECTION BY DEFINITION BEND SECTION BY DEFINITION THROAT SECTION WEIR CREST TAPER 4 1 TO 6 1 u SLOPE TAPERED INLET MITERED FACE Figure 31 10F 1
40. ation 4 Culvert location in both plan and profile should approximate the alignment of the natural channel to avoid sediment build up in the barrel 5 A culvert should be designed to accommodate debris or proper provisions should be made for debris maintenance 6 A culvert should be located and designed to present a minimum hazard to traffic and pedestrians e The detail of documentation for each culvert site should be commensurate with the risk and importance of the structure Design data and calculations should be assembled in an orderly fashion and retained for future reference as provided for in Chapter Twenty eight 8 Where necessary as directed by INDOT some means should be provided for personnel and equipment access to facilitate maintenance 31 3 0 DESIGN CRITERIA 31 3 01 Definition Design criteria are the standards by which a policy is implemented They form the basis for the selection of the final design configuration Listed below by categories are the design criteria which should be considered 31 3 02 Site Criteria The following apply 1 Structure Type Selection A culvert is used at the locations as follows a where a bridge is not hydraulically required b where debris and ice are tolerable and e where its use will be more economical than a bridge A bridge is used as follows where more economical than culvert to avoid floodway encroachment to accommodate ice or large debris and
41. be provided If the structure requires a deformed corrugated interior pipe material at least 1 5 ft of cover must be provided The cover for a circular pipe structure should not exceed 100 ft The cover for a deformed corrugated interior pipe structure should not exceed 13 ft If the pavement grade or structure invert elevations cannot be adjusted to satisfy the cover criteria discussed above contact the Hydraulics Team for additional instructions 31 3 05 05 Pipe Extension Structure Sizing Process The sizing of a pipe extension structure should be in accordance with the following 1 Match Existing Pipe Size and Interior Designation If practical the pipe extension should be the same size and material as the existing pipe However at this stage it is only necessary to identify the required interior designation for the extension 22 Perform Appropriate Hydraulic Analysis appropriate hydraulic calculations must be performed to verify whether the extended structure satisfies the required design criteria Because the structure s interior designation is known it is only necessary to perform hydraulic calculations appropriate for that interior designation If the extended structure satisfies the required design criteria the structure sizing process is complete If the extended structure does not satisfy the required design criteria the designer must reevaluate whether the existing structure can be replaced with a new structure If
42. by Contract INSPECTOR DATE OVERSIZE BOX CULVERT SEGMENTS WEIGHT AND LENGTH Figure 31 4B OVERALL INLET CONTROL CURVE app SUBMERGED ORFICE FLOW Ty HEADWATER UN UNSUBMERGED WEIR FLOW TRANSITION ZONE FLOW UNSUBMERGED SUBMERGED AND TRANSITION Figure 31 5A FLOW TYPE Figure 31 5B FLOW TYPE V Figure 31 5C SECTION 4 FLOW TYPE IV Figure 31 5D ERY Ve SECTION 2 HW D e 4 4 A 4 gt gt gt gt gt gt 5 5 b b b gt gt gt gt 4 4 A D e gt e gt gt 4 gt gt gt b b b b gt gt gt gt 4 4 A A gt gt e gt gt gt gt 5 b b b b gt gt gt gt 4 a 4 5 gt gt gt gt gt gt gt gt H b b b b b 5 bk gt gt 4 4 A D E A gt 0 D b b b b b Lb gt gt gt gt gt A a a 5 Ar gt TW RR gt VOSS SSK RE FLOW TYPE VI Figure 31 5E TT TSS dE db T T 4 ty ES db T T T TAT T AL FLOW TYPE VII Figure 31 5F HW FLOW TYPE II TW lt Figure 31 5G FLOW TYPE III TW gt dec Figure 31 5H HEADWATER ELE
43. c designs are performed for smooth and corrugated interior pipes the following situations are possible 1 Situation 1 The required smooth interior and corrugated interior pipe sizes are identical The structure callout on the plans should include the required pipe size No reference to an interior designation is made 2 Situation 2 The required smooth interior and corrugated interior pipe sizes are different The structure callout on the plans should indicate that the structure requires a smooth pipe of one size or a corrugated pipe of another 3 Situation 3 An acceptable pipe size can be determined for one interior designation but not the other If this occurs the structure callout on the plans should indicate the required pipe size and interior designation 4 Situation 4 No acceptable pipe size can be found for either interior designation The designer must proceed to the next trial of the culvert sizing process 31 3 05 03 Minimum Culvert Size If it is determined that a pipe is acceptable for a culvert structure the proposed pipe size must be greater than or equal to that shown in Figure 31 3B Minimum Pipe Culvert Size 31 3 05 04 Cover In addition to the minimum pipe size requirement cover is another factor that the designer must consider during the structure sizing process For a circular pipe structure a minimum of 1 ft of cover measured from the top of the pipe to the bottom of the asphalt or concrete pavement must
44. can then enter the roughness data for the main channel and overbanks 31 8 03 Rating Curve The program now has sufficient information to develop a uniform flow rating curve for the channel and provide the user with a list of options See Figure 31 8D HY8 Rating Curve Prompt Screen Selecting option T on the Irregular Channel Data Menu will command the program to compute the rating curve data and display Figure 31 8D Selecting option I will permit the user to interpolate data between calculated points The Tailwater Rating Curve Table consists of tailwater elevation TWE at normal depth natural channel velocity Vel and the shear stress at the bottom of the channel for various flow rates At the design flow rate of 148 3 ft s the tailwater elevation will be 193 7 ft The channel velocity will be 3 ft s and the shear will be 0 162 This information will be useful in the design of a channel lining if needed Entering P will command the computer to display the rating curve for the channel This curve shown in Figure 31 8E Tailwater vs Flow Rate is a plot of tailwater elevation vs flow rate at the exit of the culvert 31 8 04 Roadway Data The next prompts are for the roadway profile so that an overtopping analysis can be performed Referring to the problem statement the roadway profile is a sag vertical curve which will require nine coordinates to define Once these coordinates are input the profile will be displayed once P is e
45. cohesion of foundation soil C and ao SP ultimate adhesion between foundation soil and concrete CA These soil parameters will be provided in the geotechnical report for the structure If the geotechnical report is lacking this information it should be requested from the Production Management Division s Office of Geotechnical Services The headwalls quantities will be included in the structure quantities If a project has at least one precast concrete box structure and at least one precast concrete three sided drainage structure each with wingwalls the wingwalls quantities for both types of structures may be combined 31 4 05 04 Plans Details and Design Computations and Shop Drawings Only the conceptual layout for a precast concrete 3 sided or 4 sided structure or precast wingwalls and headwalls should be shown on the plans Once the work is under contract the fabricator will design and detail the structure For each 3 sided structure or for a 4 sided structure of greater than 12 0 span the fabricator will provide design computations and shop drawings which are to be checked by and are subject to the approval of the designer The contractor may choose to substitute a three sided structure as a cost reduction incentive Details for a hydraulically equivalent three sided structure should not be shown on the plans 31 4 05 05 Structure Size Increments 31 5 0 DESIGN EQUATIONS 31 5 01 General An exact theoretical
46. conventional end treatment with 1 1 bevels and 45 deg wingwalls will be used As each group of data is entered the user is allowed to edit incorrect entries Figure 31 8A shows the screen that summarizes the culvert information 31 8 02 02 Channel Data Next the program will prompt for data pertaining to the channel so that tailwater elevations can be determined Referring to the problem statement the channel is irregularly shaped and can be described by the eight coordinates listed The channel data prompt screen is shown as Figure 31 8B HY8 Channel Data Prompt Screen After opening the irregular channel file the user will be prompted for channel slope of 0 001 number of cross section coordinates 8 and subchannel option The subchannel option will be option 2 left and right overbanks with n 0 08 and main channel with n 0 03 The next prompt for channel boundaries refers to the number of the coordinate pair defining the left subchannel boundary and the number of the coordinate pair defining the right subchannel boundary The boundaries for this example are the 3 and 6th coordinates After this is input the program prompts for channel coordinates Once these are entered press P and the computer will display the channel cross section shown in Figure 31 8C Channel Cross Section The user can identify input errors by looking at the plot To return to the data input screens press any key If data are correct press Enter The user
47. creen 84 in x 48 in 31 81 HYS Minimization Routine Table Prompt Screen 31 8M HYS Summary of Culvert Flows Prompt Screen 31 8N Total Performance Curve 31 8 HYS Overtopping Performance Curve Prompt Screen 144 in x 48 in 31 9A Side Tapered End Treatment 31 9B Side Tapered End Treatment Upstream Depression Contained Between Wingwalls 31 9C Slope Tapered End Treatment with Vertical Face 31 9D Inlet Control Performance Curves Schematic 31 9E Culvert Performance Curve Schematic 31 10A Recommended Manning s n Value 31 10B Entrance Loss Coefficients Outlet Control Full or Partly Full 31 10 Entrance Loss Coefficients Standard INDOT Culverts 31 10D Editable Culvert Design Form Conventional End Treatment 31 10E Editable Culvert Design Form Tapered End Treatment 31 10F Editable Culvert Design Form Mitered End Treatment CHAPTER THIRTY ONE CULVERTS 31 1 0 INTRODUCTION 31 1 01 Definition of a Culvert A culvert is defined as the following 1 a structure pipe cast in place reinforced concrete precast reinforced concrete structural plate arch etc which is designed hydraulically to take advantage of submergence to increase hydraulic capacity 2 a structure used to convey surface runoff through an embankment 3 a structure as distinguished from a bridge which is covered with embankment and is composed of structural material around the entire perimeter although it can be supported on spread footings wit
48. d perimeter of the barrel ft 2 2 Exit loss Ho Ss Equation 31 5 6 5 Where Va channel velocity downstream of the culvert ft s usually neglected see Equation 31 5 5 If neglected 2 H Hy ES Equation 31 5 7 2g Barrel losses Hg Hy Equation 31 5 8 2 2 H Jun 287 JE g Energy Grade Line The energy grade line represents the total energy at a point along the culvert barrel Equating the total energy at Sections 1 and 2 upstream and downstream of the culvert barrel in Figure 31 5D Flow Type IV the resulting relationship is as follows 2 2 HW EE Equation 31 5 9 5 5 Where HWo headwater depth above the outlet invert ft Vy approach velocity ft s TW tailwater depth above the outlet invert ft Va downstream velocity ft s Hi sum of all losses Equation 31 5 1 9 Hydraulic Grade Line The hydraulic grade line is the depth to which water would rise in vertical tubes connected to the sides of the culvert barrel In full flow the energy grade line and the hydraulic grade line are parallel lines separated by the velocity head except at the inlet and the outlet 31 5 04 03 Nomographs The following describes the assumptions for the culvert nomographs in the FHWA Hydraulics Library CD 1 Full Flow The nomographs were developed assuming that the culvert barrel is flowing full and that the following apply a TW gt D Flow Type IV see Figure 31 5D or dc D Flo
49. d the flow across the roadway and can be determined by performing the following steps a Select a range of flow rates and determine the corresponding headwater elevations for the culvert flow alone These flow rates should occur above and below the design discharge and include the entire flow range of interest Both inlet and outlet control headwaters should be calculated b Combine the inlet and outlet control performance curves to define a single performance curve for the culvert c If the culvert headwater elevation exceeds the roadway crest elevation overtopping will begin Calculate the upstream water surface depth above the roadway for each selected flow rate Use these water surface depths and Equation 31 5 12 to calculate flow rates across the roadway 4 Add the culvert flow and the roadway overtopping flow at the corresponding headwater elevations to obtain the overall culvert performance curve as shown in Figure 31 5 I Overall Performance Curve 31 6 0 DESIGN PROCEDURES The following design procedure provides a convenient and organized method for designing a culvert for a constant discharge considering inlet and outlet control The procedure does not address the affect of storage which is discussed in Chapter Thirty five and Section 31 9 0 Storage will not be considered in the design of a structure which is not part of a detention facility The following also applies 1 The designer should be familiar with all equation
50. di dia Des d ca 37 316 0 DESIGN PROGEDURES AGS aide 38 3127 0 DESIGN 43 31 8 0 MICROCOMPUTER SOLUTION ao aaa aaa aa oaza aa aaa aaa waza entree 48 3148 01 OVervISW qus b stetit dete Scd RACE A JO a CE 48 3128 02 Data E EE 48 31 8 02 01 Culvert DAA ei RC i A W a 48 31 8 02 02 Channel Sd nue 48 31 8 03 Rating Curve s s i 49 18 04 R oadway waski ot NES 49 15 00 Data SUITE o Sie did oi Ltd 50 31 8 06 Performance Curve for Culvert Size of 132 in x 48 in 50 31 8 07 Performance Curve for Culvert Size of 144 in x 48 1 50 31 8 08 Performance Curve for Culvert Size of 84 in x 481 51 31809 Minimize Culvert Spans een 51 31 8 10 Overtopping Performance Curve Culver Size of 144 in x 48 in 32 3128 NUM 52 31 9 0 IMPROVED END TREATMENTS 53 3159 General ecu fd iih a EE 53 3150102 S e E 53 519 03 Slope Tapered ids ean oc RU ERO MORIR DUE D IU IN Os Urat US Ee 54 31 9 04 Hydraulic DesIgn een eae ER ege eh tena dee 54 31 9 04 01 Inlet Control 55 31 9 04 02 Outlet 55 34159 Despont Methods 55 100 TABTESAND ee nter KAWKA ARA DU
51. dit the file and then E again to edit the culvert size The prompts will be the same as they were for the 144 in x 48 in culvert The user will return to the Culvert Data Summary Table directly without seeing the tailwater and overtopping menus again Press F to rename the data file or press Enter to save the changes into the current file and return to the Culvert Program Options Menu The performance of this culvert can be checked by selecting option S for no overtopping The performance curve table shown as Figure 31 8K HY8 Performance Curve Prompt Screen 84 in Span by 48 in Rise appears Check the backwater for of 148 3 Pis as follows BW Headwater Elevation Inlet Elevation 7W depth BW 194 9 190 7 3 3 2 0 9 ft 1 ft therefore OK Therefore a reinforced concrete box culvert of 84 in x 48 in RCB will be adequate if the Allowable Backwater ABW is increased to 12 in 31 8 09 Minimize Culvert Span Rather than using a series of trials to increase or reduce the culvert headwater to an acceptable level as in the preceding examples the Minimize Culvert Span feature of HY8 can be used This feature is intended to allow the designer to use HY8 as a tool to perform culvert design for a circular box elliptical or arch shaped culvert based on a user s defined allowable headwater elevation assuming no overtopping This feature can be activated by pressing M Once this option is selected the user inputs the al
52. e paved or unpaved slope 0 7 Headwall or headwall and wingwalls square edge 0 5 End Section conforming to fill slope 0 5 Beveled edges 33 7 deg or 45 deg 0 2 Side or slope tapered inlet daw 0 2 Box Reinforced Concrete Wingwalls parallel extension of sides Squate edsbed at E 0 7 Wingwalls at 10 deg to 25 deg or 30 deg to 75 deg to barrel Squate edsed SOME 0 5 Headwall parallel to embankment no wingwalls Square edged on E 0 5 Rounded on 3 edges to radius of 1 12 barrel dimension or beveled edges on 3 sides 0 2 Wingwalls at 30 deg to 75 deg to barrel Crown edge rounded to radius of 1 12 barrel dimension or beveled top edge 0 2 Side or slope tapered inlet 0 2 An end section conforming to fill slope made of either metal or concrete is the section commonly available from manufacturers From limited hydraulic tests it is equivalent in operation to a headwall in both inlet and outlet control An end section incorporating a closed taper in its design may have a superior hydraulic performance Such a section can be designed using the information shown for the beveled inlet ENTRANCE LOSS COEFFICIENTS Outlet Control Full or Partly Full Figure 31 10B 1 with square edge 2 2 with square edge e 03 Anchor from fill
53. e outlet velocity or energy dissipator design 4 Computer Software The 8 hydraulics computer software and FHWA Hydraulics Library CD design methods are acceptable for structure sizing 31 5 03 Inlet Control For inlet control the control section is at the upstream end of the barrel the inlet The flow passes through critical depth near the inlet and becomes shallow high velocity supercritical flow in the culvert barrel Depending on the tailwater a hydraulic jump may occur downstream of the inlet 31 5 03 01 Headwater Factors These include the following l Headwater depth is measured from the inlet invert of the inlet control section to the surface of the upstream pool 2 Inlet area is the cross sectional area of the face of the culvert The inlet face area 1s the same as the barrel area sA Inlet edge configuration describes the entrance type Inlet edge configurations include thin edge projecting mitered square edge in a headwall and beveled edge See Section 31 10 0 for the edge configuration of INDOT inlet 4 Inlet shape is the same as the shape of the culvert barrel Shapes include rectangular circular elliptical and arch Check for an additional control section if different than the barrel 31 5 03 02 Hydraulics Three regions of flow are shown in Figure 31 5A Unsubmerged Submerged and Transition These are described as follows 1 Unsubmerged For headwater below the inlet c
54. erformanc CurVe un ii ZEE 5 31 7 1 Nomograph Design Example Site Data a 5 31 7 2 Nomograph Design Example Downstream Channel Section 5 31 7A Chart 17 and Performance Curve for Design Example sees 5 31 8A HYS Data Input Prompt Screen 5 31 8B HY8 Channel Data Prompt Screen A AAS 5 Channel Cross Se Ct u A A W A aQ 5 31 8D HY8 Rating Curve TEE 5 31 8E Tailwater vs Flow Rate waski ad 5 3 F Roadway Profile y y ua 5 31 8G HYS Data Summary Prompt Screen EA OE 5 31 8H HYS Performance Curve Prompt Screen 132 in x Am 5 31 8 I Inlet Outlet Control Headwaters 5 31 8J HYS Performance Curve Prompt Screen 144 in x 48 In 5 31 8 HYS Performance Curve Prompt Screen 84 in x 48 5 31 81 HYS Minimization Routine Table Prompt Screen 6 31 8 HYS Summary of Culvert Flows Prompt Screen 6 31 8N Total Perrormatee EE 6 31 8 HYS Overtopping Performance Curve Prompt Screen 144 in x 48 in 6 SOA Side Tapered End Nee EE 6 3 9B Side Tapered End Treatment Upstream Depression Contained Between Wingwa
55. f foundation undermining and the potential for foundation undermining f structure settlement g timber decay h roadway geometry hydraulic adequacy and j approach erosion 2 Metal Pipe Items to check when inspecting a metal pipe include but are not limited to those as follows a corrosion including holes which could cause erosion of the surrounding backfill material and b excessive deformation A metal pipe found to be in poor condition should be considered for slip lining or replacement 3 Concrete Pipe Items to check when inspecting a concrete pipe include but are not limited to those as follows cracking efflorescence delaminating or spalling of concrete exposed or corroded concrete reinforcement deterioration at widening joints settlement or separation of joints allowing backfill material into the pipe and eo ao gp deterioration of the structure A concrete pipe found to be in poor condition should be considered for resetting slip lining or possibly replacement 4 Jacking a Pipe If a pipe is to be jacked under a road space should be provided for a jacking pit Temporary right of way will be required if there is not sufficient permanent right of way The designer should discuss this issue at the preliminary field check 31 4 04 02 Culvert Modification A Structure Data Table should be included in the plans for drainage structures requiring modification Detail sheets should be p
56. gment are then added together to determine the total flow 2 The length can be represented by a single horizontal line one segment The length of the weir is the horizontal length of this segment The depth is the average depth area length of the upstream pool above the roadway Total flow is calculated for a given upstream water surface elevation using Equation 31 5 9 The following applies 1 Roadway overflow plus culvert flow must equal total design flow 2 trial and error process is necessary to determine the flow passing through the culvert and the amount flowing across the roadway 3 Performance curves for the culvert and the road overflow may be summed to yield an overall performance 31 5 07 Performance Curves Performance curves are plots of flow rate versus headwater depth or elevation velocity or outlet scour The culvert performance curve is composed of the controlling portions of the individual performance curves for each of the following control sections see Figure 31 5 1 Overall Performance Curve as follows l Inlet The inlet performance curve is developed using the inlet control nomographs 2 Outlet The outlet performance curve is developed using Equations 31 5 1 through 31 5 10 the outlet control nomographs or backwater calculations 3 Roadway A roadway performance curve is developed using Equation 31 5 12 4 Overall An overall performance curve is the sum of the flow through the culvert an
57. gure 31 8 O BEVEL OPTIONAL THROAT SECTION ELEVATION SYMMETRICAL WINGWALL FLARE ANGLES FROM B 15 TO 90 f B L4 CL TAPER 4 1 TO 6 1 PLAN SIDE TAPERED END TREATMENT Figure 31 9A SECTION SYMMETRICAL WINGWALL ANGLE FACE SECTION 2 TAN WINGWALL ANGLE D 2 2T SIDE TAPERED END TREATMENT Upstream Depression Contained Between Wingwalls Figure 31 9B SYMETRICAL WINGWALL FLARE ANGLES FROM 159 9090 4 1 TO 6 1 L 4 SLOPE TAPERED END TREATMENT WITH VERTICAL FACE Figure 31 9C Headwater Elevation Face Control Bend Control J K Throat Control Overall Performance X 2 Discharge INLET CONTROL PERFORMANCE CURVES Schematic Figure 31 90 re 7 Headwater Face Control Curve Throat Control Curve Outlet Control Curve Performance Curve Discharge CULVERT PERFORMANCE CURVE Schematic Figure 31 9E Type of Conduit Wall Description Smooth Walls 0 012 0 015 2 75 in x 0 5 in corrugations 0 024 6 in x 1 in corrugations 0 024 Corrugated Metal Pipe or in x I in ti 024 Box Annular or Helical Pipe 2 i x kk Se Get 3 in x l in corrugations 0 024 see HDS 5 6 in x 2 in structural plate 0 033 0 035 9 25 in x 2 5 in structural plate 0 033 0 037 Note 1 The value indicated in this table is the rec
58. h the streambed serving as the bottom of the culvert or 4 a structure with less than a 20 ft span length along the centerline of roadway between extreme ends of openings for multiple barrels Figure 31 1A Maximum Span Length for Culvert provides schematics which define a culvert based on span length for various structural configurations However a structure designed hydraulically as a culvert is treated as discussed in this Chapter regardless of span length In addition the following apply to defining a culvert 1 Mainline Culvert A structure under mainline roadway 2 Public Road Approach Culvert A structure under public road approach 3 Drive Culvert A structure under a drive or field entrance 4 Concrete Culvert Extension New construction that extends an existing reinforced concrete slab top box or arch culvert structure Acceptable methods for constructing the extension include cast in place reinforced concrete or installation of precast reinforced concrete box sections 31 1 02 Purpose This Chapter provides design procedures for the hydraulic design of a highway culvert which are based on FHWA Hydraulic Design Series Number 5 HDS 5 Hydraulic Design of Highway Culverts This Chapter also provides the following 1 the results of culvert analysis using microcomputers which emphasizes the use of the HYDRAIN system and the 8 culvert analysis software and 2 a summary of the design philosophy included in t
59. he AASHTO Highway Drainage Guidelines Chapter IV 31 1 03 Definitions The following are definitions of concepts to be considered in culvert design 1 Backwater The increase in water surface elevation caused by the introduction of a culvert into an open channel or other open drainage system gt Critical Depth dc The depth at which the specific energy of a given flow rate is at a minimum For a given discharge and cross section geometry there is only one critical depth 3 Crown The inside top of a culvert 4 Flow Type The USGS has established culvert flow types which assist in determining the flow conditions at a particular culvert site Diagrams of these flow types are provided in Section 31 5 0 5 Free Outlet A free outlet has a tailwater equal to or lower than critical depth For a culvert having a free outlet lowering of the tailwater has no effect on the discharge or the backwater profile upstream of the tailwater 6 Improved End Treatment Improved Inlet An improved end treatment has an entrance geometry which decreases the flow contraction at the end treatment and thus increases the capacity of a culvert The end treatment is referred to as side or slope tapered walls or bottom tapered 7 Invert The flowline of the culvert inside bottom 8 Normal Flow Normal flow occurs in a channel reach if the discharge velocity and depth of flow do not change throughout the reach The water surface and channel botto
60. he approach velocity head 31 5 04 Outlet Control Outlet control has depths and velocities which are subcritical The control of the flow is at the downstream end of the culvert the outlet The tailwater depth is either assumed to be critical depth near the culvert outlet or the downstream channel depth whichever is higher In a given culvert the type of flow is dependent on all of the barrel factors AII of the inlet control factors also influence the culvert in outlet control as follows 1 Interior Designation The pipe culvert interior designation i e the barrel roughness will be either smooth or corrugated See Section 31 3 05 02 for INDOT practice The roughness is represented by hydraulic resistance coefficient such as the Manning s n value Manning s n values are provided in Section 31 10 0 2 Barrel Area Barrel area is measured perpendicular to the flow 3 Barrel Length Barrel length 15 the total culvert length from the entrance invert to the exit invert Because the design height of the barrel and the slope influence the actual length an approximation of barrel length is necessary to begin the design process 4 Barrel Slope Barrel slope is the actual slope of the culvert barrel and is often the same as the natural stream slope However if the culvert inlet or outlet is raised or lowered the barrel slope is different from the stream slope 31 5 04 01 Tailwater Elevation Tailwater is based on the downst
61. he culvert end Should be used for a culvert with headwalls c Should be of minimum 20 in depth or as shown in the INDOT Standard Drawings or Standard Specifications 8 Weep Hole A weep hole should not be used 31 3 06 03 Pipe Length Determination After the structure size and cover have been determined the designer must determine the required length The design length for a culvert structure should be rounded to the next higher 1 5 ft 31 3 06 04 Buoyancy Protection Pipe end sections or concrete anchors where a projecting end treatment or outlet is used or other means of anchoring to provide buoyancy protection should be considered for a flexible culvert The seriousness of buoyancy depends on the steepness of the culvert slope depth of the potential headwater debris blockage may increase flatness of the upstream fill slope height of the fill large culvert skew or mitered ends See the INDOT Standard Drawings and Standard Specifications 31 3 06 05 Relief Opening Where a culvert serving as a relief opening has its outlet set above the normal stream flow line precautions should be made to prevent headcutting or erosion from undermining the culvert outlet 31 3 06 06 Erosion and Sediment Control Temporary measures should be shown on the construction plans The measures may include the use of a silt box brush silt barrier filter cloth temporary silt fence or check dam For more information see Chapter Thirty se
62. icrocomputer analysis 12 Step 12 Documentation Prepare a Report which includes the Culvert Design Form shown on Figure 31 7A Chart 17 and Performance Curve for Design Example 31 8 0 MICROCOMPUTER SOLUTION 31 8 01 Overview Culvert hydraulic analysis can also be accomplished with the aid of the HYDRAIN software The following example has been produced using the 8 Culvert Analysis Microcomputer Program It is the computer solution of the data provided in Section 31 7 0 Although Trials 1 and 2 of the culvert design process can be worked on HYS they are not shown in this example Trial 3 the reinforced concrete box culvert is shown The screens shown in the figures may not exactly match the version of HY8 available to the user because some editorial changes have been made to fit the screens in this text for presentation 31 8 02 Data Input After creating a file the user will be prompted for the discharge range site data and culvert shape size material and end treatment type The discharge range for this example will be from 0 to 222 ft s The site data are entered by providing culvert invert data The data input prompt screen is shown as Figure 31 8A 8 Data Input Prompt Screen If embankment data points are input the program will fit the culvert in the fill and subtract the appropriate length 31 8 02 01 Culvert Data As an initial size estimate try a concrete box culvert 132 in x 48 in For the culvert assume that a
63. ign Form provided in Section 31 10 0 The design nomographs included in HDS 45 are used to design the tapered end treatment The design procedure is similar to designing a culvert with other control sections face and throat The result will be one or more culvert designs with or without tapered end treatments all of which satisfy the site design criteria The designer must select the best design for the site under consideration The goal is to maintain control at the efficient throat section in the design range of headwater and discharge This is because the throat section has the same geometry as the barrel and the barrel is the most costly part of the culvert The end treatment face is then sized large enough to pass the design flow without acting as a control section in the design discharge range Some slight oversizing of the face is beneficial because the cost of constructing the tapered end treatment is minor compared with the cost of the barrel Performance curves should be considered in understanding the operation of a culvert with a tapered end treatment Each potential control section face throat or outlet has a performance curve based on the assumption that a specific section controls the flow Calculating and plotting the performance curves results in a graph similar to that shown in Figure 31 9E Culvert Performance Curve Schematic including the face control throat control and outlet control curves The overall culvert perfo
64. it is not practical to replace the existing pipe because of construction method traffic maintenance or other constraints contact the Hydraulics Team for further instructions 31 3 05 06 Concrete Culvert Extension Sizing Process If an existing cast in place reinforced concrete slab top culvert box culvert or arch culvert requires extension the designer must decide whether the extension will be constructed using cast in place reinforced concrete or precast reinforced concrete box sections Once the extension method has been determined the appropriate culvert design criteria must be checked to verify that the extended structure satisfies the hydraulic requirements If the analysis indicates that the extended structure does not satisfy the hydraulic requirements the designer must reevaluate whether the existing structure can be removed and replaced with a new structure If it is not possible to replace the existing culvert because of construction method traffic maintenance or other constraints contact the Hydraulics Team for further instruction 31 3 06 Other Culvert Features 31 3 06 01 Culvert Skew The culvert skew should not exceed 45 deg as measured from a line perpendicular to the roadway centerline without the approval of the Hydraulics Engineer 31 3 06 02 Inlet or Outlet End Treatment The culvert end treatment type should be selected from the list shown below based on the given considerations and the end treatment coefficient Ke
65. lls 6 31 9 Slope Tapered End Treatment with Vertical Face 6 31 9D Inlet Control Performance Curves 6 31 9E Culvert Performance Curve Schematic 6 31 10 Recommended Manning s n Value uin ertt tete e etae ia petiit sers 6 31 10B Entrance Loss Coefficients Outlet Control Full or Partly Full 6 31 10C Entrance Loss Coefficients Standard INDOT Culverts 6 31 10D Editable Culvert Design Form Conventional End Treatment 6 31 10E Editable Culvert Design Form Tapered End Treatment 6 31 10F Editable Culvert Design Form Mitered End Treatment 6 CHAPTER TEIRTYONE oed AO 7 311 0 INTRODUCTION uy ha v Pech dedit tei uei duisi quts EI RD 7 21 501 D fimton ot d CUlVert wood O ana Meu E 7 PUt USC WaS asa O A A A 8 3T 1 05 DefinitIoBS mediis tote a oa an e expeti oed 8 31 1 04 Symbols ili GA En Y 9 31 20 POLICY I 9 36201 ooo Gru do edt ed uud 9 C ulvert
66. lowable headwater elevation That elevation will be the basis for adjusting the user s defined culvert size for the design discharge The program will adjust the culvert span by increasing or decreasing in it in 6 in increments It will compute the headwater elevation for the span and compare it with the user s defined allowable headwater If the computed headwater elevation is lower than or equal to the defined allowable headwater elevation the minimization routine will stop and the adjusted culvert can be used for the remainder of the program Other hydraulic parameters are also computed while performing the minimization routine These hydraulic parameters which are part of the output of the minimization routine table as shown in Figure 31 81 HY8 Minimization Routine Table Prompt Screen must be printed from this screen because they are not printed with the output listing routine The AHW of 195 ft based on the inlet elevation of 190 7 ft TW of 3 3 ft and allowable backwater of 1 ft yields the results shown in Figure 31 8L This feature is a timesaver as it avoids the need for repetitively editing a culvert size to obtain a controlling headwater elevation 31 8 10 Overtopping Performance Curve Culver Size of 144 in x 48 in Return to the 144 in x 48 in culvert to determine the amount of overtopping and the actual headwater from the Culvert Program Options Menu and select O for overtopping Figure 31 8M Summary of Culvert Flows Prompt
67. m will be parallel 9 Slope The following applies a A steep slope occurs where critical depth is greater than normal depth b A mild slope occurs where critical depth is less than normal depth 10 Submergence The following applies a A submerged outlet occurs where the tailwater elevation is higher than the crown of the culvert b A submerged inlet occurs where the headwater is greater than 1 2D where D is the culvert diameter or barrel height 31 1 04 Symbols To provide consistency within this Chapter and throughout this Manual the symbols in Figure 31 1B Culvert Symbols will be used These symbols have wide use in culvert publications 31 2 0 POLICY 31 2 01 Definition Policy is a set of goals that establish a definite course of action or method of action and that are selected to guide and determine present and future decisions Policy is implemented through design criteria for making decisions see Section 31 3 0 31 2 02 Culvert Policy The following policies are specific to a culvert 1 Each culvert should be hydraulically designed However the minimum pipe size specified in Section 31 3 05 03 will sometimes control 2 The design storm frequency frequencies selected should consistent with the criteria described in Section 31 3 03 3 Survey information should include topographic features channel characteristics high water information existing structure data and other related site specific inform
68. ments Specialty structures include those described below method for a box culvert is to extend it to the point where the roadway sideslope intercepts the stream flowline The sideslope at the end of a box culvert should be protected with guardrail or be located beyond the clear zone 31 4 05 02 Precast Concrete Oversize Box Structure A precast concrete oversize box structure may be recommended by the Hydraulics Team A box structure is considered oversize if its clear span length is more than 12 0 but not more than 20 0 Product information is available from local suppliers The hydraulic recommendations letter will indicate if a three sided structure with a base slab is an acceptable alternate to an oversize box structure designer should consult with the Hydraulics Team for guidance as to whether the two structure types are interchangeable for the specific site cost comparison should be used in making the final structure selection If the distance between the top of the structure and the top of the pavement section is less than 2 ft as measured at the edge of travel lane all top slab reinforcement in a box structure or all reinforcement in a three sided structure should be epoxy coated A note should be placed in the Structure Data Table s comments column indicating this An oversize box culvert should be laid out so that the total structure length is a multiple of the box segment length for the given box size It is no
69. nstream Channel See Chapter Thirty Minimum required data are cross section and slope of channel and the rating curve for the channel Perform analysis for each required design storm magnitude Step 4 Summarize Data On Design Form Perform analysis for each required design storm magnitude Steps 7 8 and 9 must be performed for each structure type analyzed in Trials 1 through 6 for the design storm magnitudes appropriate for allowable headwater a See Chart in Section 31 10 0 b Data from Steps 1 3 c Step 5 Select Design Discharge a See Section 31 3 0 and Chapter Twenty nine b Determine flood frequency from criteria Determine Step 6 Perform Structure Sizing Process a See Section 31 3 0 b and roadway serviceability c Continue with trials until hydraulic design is complete d Select acceptable structure size type and pipe interior designation if applicable and select the end treatment 10 11 Step 7 Determine Inlet Control Headwater Depth HW Use the inlet control nomograph FHWA Hydraulics Library CD A plastic sheet with a matte finish can be used to mark on so that the nomographs can be preserved a Locate the size or height on the scale b Locate the discharge 1 For a circular shape use discharge 2 For a box shape use Q per foot of width c Locate HW D ratio 1 Use a straightedge 2 Extend a straight line from the culvert size through the flow rate
70. nt The face section is approximately the same height as the barrel height and the inlet floor is an extension of the barrel floor The end treatment roof may slope upward slightly provided that the face height does not exceed the barrel height by more than 10 percent 1 1D The intersection of the tapered sidewalls and the barrel is defined as the throat section There are two possible control sections the face and the throat HW shown in Figure 31 9A is the headwater depth measured from the face section invert HW is headwater depth measured from the throat section invert The throat of a side tapered end treatment is a very efficient control section The flow contraction is nearly eliminated at the throat The throat is always slightly lower than the face so that more head is exerted on the throat for a given headwater elevation The beneficial effect of depressing the throat section below the streambed can be increased by installing a depression upstream of the side tapered end treatment See Figure 31 9B Side Tapered End Treatment Upstream Depression Contained Between Wingwalls For this type of depression the floor of the barrel should extend upstream from the face a minimum distance of D 2 before sloping upward more steeply The length of the resultant upstream crest where the slope of the depression meets the streambed should be checked to ensure that the crest will not control the flow at the design flow and headwater If the cre
71. ntered as illustrated in Figure 31 8F Roadway Profile The other data required for overtopping analysis are roadway surface or weir coefficient and the embankment top width For this example the roadway is paved with an embankment width of 50 8 ft 31 8 05 Data Summary AII of the data has now been entered and the summary table is displayed as shown in Figure 31 8G HY8 Data Summary Prompt Screen At this point the data can be changed or the user can save the data and continue by pressing Enter which will bring up the Culvert Program Options Menu 31 8 06 Performance Curve for Culvert Size of 132 in x 48 in From the Culvert Program Options Menu the culvert performance curve table can be obtained by selecting option 5 If option 5 is selected the program will compute the performance curve table without considering overtopping in the analysis Because this 132 in x 48 in culvert is a preliminary estimate the performance without considering overtopping is calculated and is shown as Figure 31 8H HY8 Performance Curve Prompt Screen 132 in Span by 48 in Rise The table indicates the controlling headwater elevation HW the tailwater elevation and the headwater elevations associated with all possible control sections of the culvert It is apparent from the table that at 148 3 HW 194 2 ft which exceeds design headwater of 194 1 ft Consequently the 132 in x 48 in box culvert is inadequate for the site conditions Figure 31
72. ommended Manning e n design value The actual field value for an older existing pipeline may vary depending on the effects of abrasion corrosion deflection and joint conditions A concrete pipe with poor joints and deteriorated walls may have an n value of 0 014 to 0 018 A corrugated metal pipe with joint and wall problems may also have a higher n value and may experience shape changes which can adversely affect the general hydraulic characteristics of the culvert Note 2 For further information concerning Manning s n value for selected conduits consult Hydraulic Design of Highway Culverts Federal Highway Administration HDS 5 163 RECOMMENDED MANNING S n VALUE Figure 31 10A Type of Structure and Design of Entrance Coefficient Kp Pipe Concrete Mitered to conform to fill Slope saa 0 7 End Section conforming to fill slope 0 5 Projecting from fill square cut O Seege 0 5 Headwall or headwall and wingwalls SJMALCSAZE See 0 5 Rounded radius UI 0 2 Socket end of pipe 0 2 Projecting from fill socket end groove end 0 2 Beveled edges 33 7 deg or 45 deg 0 2 Sides OPSIoDS Lapered E zd Uo adiens 0 2 Pipe or Pipe Arch Corrugated Metal Projecting from fill no eene 0 9 Mitered to conform to fill slop
73. or large body of water the designer should use the high water elevation that has the same frequency as the design flood if events are known to occur concurrently statistically dependent to determine the tailwater 31 3 04 06 Storage Temporary or Permanent Storage should not be considered in the hydraulic design of a culvert 31 3 05 Culvert Sizing Process 31 3 05 01 Priority System The culvert sizing process is performed in accordance with a priority system system consists of six trials where specific installations are considered prior to evaluating other structure types The design priority system is as follows 1 Trial 1 Single Circular Pipe Installation 2 Trial 2 Single Deformed Pipe Installation Trial 3 Single Specialty Structure Installation Trial 4 Multiple Circular Pipes Installation Trial 5 Multiple Deformed Pipes Installation OMR W Trial 6 Multiple Specialty Structures Installation The principles of the priority system are summarized below 1 A pipe structure is preferred to a specialty structure e g precast reinforced concrete box section precast reinforced concrete three sided culvert structural plate arch 2 A circular pipe is preferred to a deformed pipe 3 A single cell installation 15 preferred to a multiple cell installation Section 31 3 0 provides a decision flowchart for each of the six trials in the priority system as the following figures 31 3C Culvert Design Process
74. osion and Sediment Control 40 DESIGN PHILOSOPHY sei GAS AOU Z EE EE 31 4 03 Meth ds A 31 4 03 01 Structure Kn 31 4 03 02 Hydrology Methods avse 31 4 03 03 Computational Methods AAA AAA 31 4 03 04 Computer Software aso O A WITH 31 4 04 Modifying or Replacing an Existing Culvert 31 4 04 01 Determining Need for Culvert Modification or Replacement 31 4 04 02 Culvert Modification 31 4 04 03 Culvert RE 31 4 04 04 Backfill Materials 21530 DESIGN EQUATIONS 31 5 01 General ESO ER AO OGAE 31 5 03 31 5 03 01 Headwater Factors 31 5 03 02 TEE 313 001 Nors SPEDE Le 31 5 04 01 Tailwater Elevation ashaka 31 5 04 02 Hydraull s T 23153 0403 31309 Outlet Vb 35 31 5 05 01 filet Control S aa dac di BRO A adi 35 31 3 05 02 Outlet C ontroL s ssaka asun EE See aca ege 35 31 5 06 Roadway Oops 36 315 071 Performance Curves eee au
75. ream water surface elevation Backwater calculations from a downstream control a normal depth approximation flood insurance studies or IDNR historic flood profiles are used to define the tailwater elevation see Section 31 3 03 31 5 04 02 Hydraulics Full flow in the culvert barrel is assumed for the analysis of outlet control hydraulics Outlet control flow conditions can be calculated based on an energy balance from the tailwater pool to the headwater pool See Figure 31 5D Flow Type IV The following equations apply 1 Losses Hj Where Hy H H H 2 Velocity V Where V Hg Hy H H H Equation 31 5 1 total energy loss ft entrance loss ft friction losses ft exit loss or velocity head ft bend losses ft see HDS 5 losses at junctions ft see HDS 5 losses at grates ft see HDS 45 Equation 31 5 2 average barrel velocity ft s flow rate ft s cross sectional area of flow with the barrel full f V 2 Velocity head H 5s Equation 31 5 3 8 Where g acceleration due to gravity 32 2 ft s KV Entrance loss H i Equation 31 5 4 8 Where Kg entrance loss coefficient see Section 31 10 0 Ln Friction loss Ber Equation 31 5 5 5 Where L length of the culvert barrel ft n Manning s roughness coefficient see Section 31 10 0 R hydraulic radius of the full culvert barrel A P ft P wette
76. rict operations or maintenance should be contacted to clean each plugged or partially plugged structure so an adequate inspection can be performed The district should be notified of changes that need to be made in the road log Once inspection of all culverts to be addressed has been completed a list of those requiring modification or replacement should be provided to the district Office of Highway Management The Office will slip line replace pipes of less than 36 in diameter requiring excavation of less than 5 ft See Section 31 4 04 02 Item 1 for an explanation of slip lining This work should be done before the road work is contracted Rehabilitation or replacement should be considered as part of the project work for a culvert of 36 in or greater diameter that has poor roadway geometry or that has a remaining life of less than the anticipated life of the proposed road work 31 4 04 01 Determining Need for Culvert Modification or Replacement Each culvert to be modified or replaced should be evaluated by an individual familiar with structure inspection 1 General Considerations The items to check include but are not limited to those as follows a structure alignment with the channel and the potential for erosion or scour b erosion of the approaches particularly the areas behind the wingwalls c loss of fill material from beneath the roadway d local and contraction scour and general channel degradation e indications o
77. rmance curve is represented by the hatched line In the range of lower discharges face control governs In the intermediate range throat control governs In the higher discharge range outlet control governs The crest and bend performance curves are not calculated because they do not govern in the design range 31 10 0 TABLES AND FORMS Section 31 10 0 includes the figures as follows 31 10 Recommended Manning s n Value These are the recommended Manning s values used in the hydraulic design of a culvert 31 108 Entrance Loss Coefficient Outlet Control Full or Partly Full This coefficient Kp is for a culvert based on the type of entrance 31 10C Entrance Loss Coefficient Standard INDOT Culvert This coefficient is for a specific culvert as shown on the INDOT Standard Drawings Editable versions of the following forms may also be found on the Department s website at www in gov dot div contracts design dmforms 31 100 Culvert Design Form Conventional End Treatment 31 10 Culvert Design Form Tapered End Treatment 31 10F Culvert Design Form Mitered End Treatment U CONCRETE SLABS CLEAR SPAN LESS THAN 20 ft Z CONCRETE BEAMS OR GIRDERS OR STEEL BEAMS EMBEDDED IN THE BACKWALL CLEAR SPAN L LESS THAN 20 ft Z STEEL 5 OR GIRDERS CONCRETE BEAMS ON BEARINGS CLEAR SPAN LESS THAN 20 ft CONCRETE B
78. rovided where required 1 Slip Lining Slip lining is a technique for rehabilitating a culvert of 18 in diameter larger Slip lining is also suitable for use for a box or arch type culvert It is completed by pushing or pulling sections of polyethylene pipe through the existing structure and filling the space between the polyethylene and existing structure with grout The capacity of a structure can often be increased due to the low friction factor of the polyethylene liner Factors to consider when deciding whether or not to slip line a structure are as follows a The structure barrel should be relatively straight and free from obstructions The backfill around the structure should be free from large voids c There should be sufficient room to work from at least one end of the existing structure d The structure should be under at least 6 5 ft of fill or in a location where a road closure is undesirable or impossible 2 Culvert Extension A culvert that is structurally and hydraulically adequate but of insufficient length may be considered for an extension Each culvert with a diameter of 50 in or greater that will be extended 5 ft or more will require a geotechnical evaluation See Section 31 3 05 05 for criteria regarding culvert extension 3 Culvert End Treatment See Section 31 3 06 02 for desirable design criteria regarding culvert end treatment gt Headwalls Anchors Removal of headwalls anchor
79. rown the entrance operates as a weir A weir is a flow control section where the upstream water surface elevation can be predicted for a given flow rate relationship between flow and water surface elevation must be determined through model tests of the weir geometry or by measuring prototype discharges These tests are then used to develop equations HDS 45 Appendix A includes the equations which were developed from model test data See Figure 31 5B Flow Type I 2 Submerged For headwater above the inlet the culvert operates as an orifice An orifice is an opening submerged on the upstream side and flowing freely on the downstream side which functions as a control section The relationship between flow and headwater can be defined based on results from model tests HDS 45 Appendix A includes flow equations which were developed from model test data See Figure 31 5C Flow Type V 3 Transition Zone The transition zone is located between the unsubmerged and the submerged flow conditions where the flow 15 poorly defined This zone 15 approximated by plotting the unsubmerged and submerged flow equations and connecting them with a line tangent to both curves 31 5 03 03 Nomographs The inlet control flow versus headwater curves which are established using the above procedure are the basis for constructing the inlet control design nomographs In the inlet control nomographs HW is measured to the total upstream energy grade line including t
80. s damages the existing structure As a minimum 40 in of new structure should be placed for each headwall removed Each protruding headwall which is not in accordance with the obstruction free zone criteria should be considered for removal or modification A headwall which is shielded from impact by guardrail should not be removed unless it is located within clearance range of the guardrail as shown in Figure 49 4A 31 4 04 03 Culvert Replacement Each culvert with a diameter of 50 in or greater that is to be replaced will require a geotechnical report and a hydraulic analysis If a legal drain is involved the county surveyor should be contacted for the replacement structure parameters County soils survey and county drainage maps are available The USGS 7 5 min series topography maps provide information regarding drainage patterns at a large scale The topography maps show rivers creeks and streams which indicate the drainage pattern of the basin as a whole The designer should provide the flow line elevation for the structure to be replaced The established temporary benchmarks should be shown on the detail sheet Cross sections should be provided where required for each culvert replacement or new installation If a culvert is already in the INSTIP program for replacement the designer should attempt to incorporate the replacement into the project work 31 4 04 04 Backfill Materials See Section 17 2 09 for culvert backfill require
81. s in Section 31 5 0 before using these procedures 2 Following design method without an understanding of culvert hydraulics can result in an inadequate unsafe or costly structure 3 The computation form has been provided in Section 31 10 0 to guide the user It includes blocks for the project description designer s identification hydrologic data culvert dimensions and elevations trial culvert description inlet and outlet control HW culvert barrel selected and comments 4 Step 1 Assemble Site Data And Project File a See Section 28 5 0 The minimum required data are as follows 1 USGS site and location maps 2 embankment cross section 3 roadway profile 4 channel cross section at outlet of proposed structure 5 photographs 6 survey sediment debris and 7 design data for nearby structures for which data is readily available b Studies and regulatory requirements by other agencies including the following 1 small dam NRCS USACOE 2 canal NRCS USACOE 3 floodplain NRCS USACOE FEMA USGS NOAA IDNR and 4 storm drain local or private including drains regulated by county drainage board Design criteria 1 review Section 31 3 0 for applicable criteria and 2 prepare analysis Step 2 Determine Hydrology See Chapter Twenty nine Minimum required data are drainage area map and a discharge Determine magnitude of each required design storm Step 3 Analyze Dow
82. s only slightly lower than the face it is likely that the face section will function as a weir or an orifice with downstream submergence within the design range At a lower flow rate and headwater the face will usually control the flow 2 Slope Tapered End Treatment The throat can be the primary control section with the face section submerged or unsubmerged If the face is submerged the face acts as an orifice with downstream submergence If the face is unsubmerged the face acts as a weir with the flow plunging into the pool formed between the face and the throat The bend section will not act as the control section if the dimensional criteria described herein are followed However the bend will contribute to the inlet losses which are included in the inlet loss coefficient Kg 31 9 04 02 Outlet Control If a culvert with a tapered end treatment performs in outlet control the hydraulics are the same as described in Section 31 5 0 for all culverts The tapered end treatment entrance loss coefficient is 0 2 for side tapered a slope tapered end treatment This loss coefficient includes contraction and expansion losses at the face increased friction losses between the face and the throat and the minor expansion and contraction losses at the throat 31 9 05 Design Methods Tapered end treatment design begins with the selection of the culvert barrel size shape and material The calculations are performed using the Culvert Des
83. st length is too short the crest may act as a weir control section 31 9 03 Slope Tapered The slope tapered end treatment also has an enlarged face section with tapered sidewalls meeting the culvert barrel walls at the throat section Figure 31 9C Slope Tapered End Treatment with Vertical Face A vertical fall is incorporated into the end treatment between the face and throat sections The fall concentrates more head on the throat section At the location where the steeper slope of the end treatment intersects the flatter slope of the barrel a third section designated the bend section is formed A slope tapered end treatment has three possible control sections the face the bend and the throat Of these only the dimensions of the face and the throat section are determined by the design procedures included herein The size of the bend section is established by locating it a minimal distance upstream from the throat so that it will not control the flow The slope tapered end treatment combines an efficient throat section with additional head on the throat The face section does not benefit from the fall between the face and throat therefore the face sections of the end treatment are larger than the face sections of an equivalent depressed side tapered end treatment The required face size can be reduced by the use of bevels or other favorable edge configurations See Figure 31 9C Slope Tapered End Treatment with Vertical Face The slope
84. t Velocity Vo and Depth d If inlet is the controlling headwater using the design storm magnitude appropriate for the velocity calculate the following a flow depth at culvert exit using normal depth or water surface profile b flow area A and c exit velocity Vo Q A If outlet is the controlling headwater using the design storm magnitude appropriate for the velocity calculate the following a flow depth at culvert exit 1 use dc if it is greater than TW 15 16 17 2 use TW if dc lt TW lt D 3 use D if it is less than TW flow area A and exit velocity Vo 2 Q A Step 12 Review Results Compare alternative design with constraints and assumptions If one or more of the following is exceeded repeat Steps 5 through 12 The barrel must have adequate cover see Section 31 3 05 04 The length should be close to the approximate length The allowable backwater should not be exceeded The roadway serviceability must be satisfied The outlet velocity should not be excessive see Section 31 3 0 Step 13 Related Designs Consider the following options see Sections 31 5 04 and 31 5 05 Improved end treatments if culvert is in inlet control and has limited available headwater Energy dissipator if Vo gt 13 ft s see Section 31 3 0 and Chapter Thirty four Sediment control storage for site with sediment concerns such as alluvial fans see Chapter Thirty seven
85. t necessary to add a tolerance for the joints between segments in determining the total structure length The available segment masses weights and lengths are shown in Figure 31 4B 31 4 05 03 Wingwalls and Headwalls for Precast Concrete Structure Wingwalls and headwalls for a precast concrete structure will be required Such wingwalls and headwalls may b precast or cast in place The information to be shown on the plans is as follows plan view showing the total length of the structure skew angle distance from roadway centerline to each end of structure and the flare angle of all wingwalls 2 elevation view of the end of the structure including wingwalls headwall span and rise of the structure should be dimensioned The heights of the headwalls should be shown wingwalls labeled A through D with a table showing all dimensions and elevations for each wingwall 4 a table summarizing the wingwall areas required B a conceptual drawing showing a typical section through each wingwall that shows the approximate footing configuration Footing dimensions should not be shown contractor is responsible for the footing design and 6 the allowable soil bearing pressure A table should be included on the plans listing the soil parameters for wingwall design as follows angle of friction between wingwall footing and foundation soil angle of internal friction of the foundation soil ultimate
86. tapered end treatment is the most complex inlet improvement recommended herein Construction difficulties are inherent but the benefits in increased performance can be significant With proper design a slope tapered end treatment passes more flow at a given headwater elevation than another configuration A slope tapered end treatment can be applied to either a box culvert or a circular pipe culvert For the latter application a square to round transition is used to connect the rectangular slope tapered end treatment to the circular end treatment pipe 31 9 04 Hydraulic Design 31 9 04 01 Inlet Control A tapered end treatment s control sections include the face the bend for a slope tapered end treatment and the throat A depressed side tapered end treatment has a possible control section at the crest upstream of the depression Each of these inlet control sections has an individual performance curve The headwater depth for each control section is referenced to the invert of the section One method of determining the overall inlet control performance curve is to calculate performance curves for each potential control section and then select the segment of each curve which defines the minimum overall culvert performance See Figure 31 9D Inlet Control Performance Curves Schematic 1 Side Tapered End Treatment The throat should be designed to be the primary control section for the design range of flows and headwaters Because the throat i
87. tion 31 3 0 31 9 0 IMPROVED END TREATMENTS 31 9 01 General An improved end treatment is a flared culvert inlet with an enlarged face section and a hydraulically efficient throat section An improved end treatment may have a depression or fall incorporated into the end treatment structure or located upstream of the end treatment The depression is used to exert more head on the throat section for a given headwater elevation Therefore an improved end treatment improves culvert performance by providing a more efficient control section the throat An improved end treatment with a fall also improves performance by increasing the head on the throat The following also applies 1 An improved end treatment is not recommended for use with a culvert flowing in outlet control because the simple beveled edge is of equal benefit 2 Design criteria and methods have been developed for two basic end treatment designs the side tapered end treatment and the slope tapered end treatment 3 Improved end treatment design charts are available for a rectangular box culvert or a circular pipe culvert 4 The use of an improved end treatment must be accompanied by an economic justification for its use subject to the approval of the Hydraulics Engineer 31 9 02 Side Tapered The side tapered end treatment has an enlarged face section with the transition to the culvert barrel accomplished by tapering the side walls Figure 31 9A Side Tapered End Treatme
88. trol Structures and may be considered as follows a where experience or physical evidence indicates the watercourse will transport a heavy volume of controllable debris b for a culvert under a high fill or where clean out access is limited However access must be available to clean out the debris control device 31 3 03 Design Storm Frequency See Figure 31 3A Design Storm Frequency Culvert 31 3 04 Hydraulic Design Criteria 31 3 04 01 Allowable Headwater AH W Allowable headwater is the depth of water that can be ponded at the upstream end of a culvert during the design flood AHW will be limited by one or more of the following 1 New Alignment The maximum backwater increase in headwater elevation over the sum of TW depth plus inlet invert elevation should not exceed 1 5 in The 1 5 in maximum may be modified as follows a the backwater dissipates to 1 5 in or less at the right of way line or b the channel is sufficiently deep to contain the increased elevation without overtopping the banks The Hydraulics Engineer must approve exceptions to the 1 5 in backwater allowance gt Existing Conditions The IDNR limits surcharge to 1 ft in an urban or rural location Existing conditions are defined as the water surface profile that results from only those encroachments that were constructed prior to December 31 1973 Although IDNR policy will allow for a slight increase over existing conditions IND
89. ures described in HDS 5 c a type of structure which may be circular deformed or specialty PRACTICE POINTER If twin box culverts are required space should not be left between them 2 Storm Drain This is one of the following a a covered structure with at least one end in a manhole inlet or catch basin and is usually a part of a system of pipes b designed using HYDRA software included in HYDRAIN or e designed using other computer models or by hand calculations See FHW A SA 96 078 Urban Drainage Design Manual HEC 22 and Chapter Thirty six and for more information 3 Specialty Structure A specialty structure can be used in either a culvert or storm drain application See Section 31 4 05 for more information on specialty structures 31 4 03 02 Hydrology Methods See Chapter Twenty nine for detailed information on hydrology A constant discharge is assumed for culvert design 15 always the peak discharge and will yield a conservatively sized structure where temporary storage is available but not used 31 4 03 03 Computational Methods Nomographs require a trial and error solution which most often provides a reliable design and require additional computations for tailwater outlet velocity hydrographs routing and roadway overtopping They are available for many culvert sizes and shapes see HDS 5 31 4 03 04 Computer Software HY 8 is the only computer program allowed for the hydraulic
90. ven The scour elevation to be shown on the Layout sheet is the scour elevation for Qo 31 4 0 DESIGN PHILOSOPHY 31 4 01 Overview The design of culvert system for a highway crossing a floodplain involves using information from other chapters in this Part e g hydrology channels Each of these should be consulted as appropriate The discussion below focuses on alternative analyses and design methods 31 4 02 Alternative Analyses A culvert alternative should be selected which satisfies the topography design policies and design criteria Alternatives should be analyzed for hydraulic equivalency risk and cost Select an alternative which best integrates engineering and economic and political considerations selected culvert should satisfy the applicable structural and hydraulic criteria and should be based on the following construction and maintenance costs risk of failure or property damage roadside safety and v ll oS land use requirements 31 4 03 Design Methods The designer should choose either of the following 1 to use culvert or storm drain or gt to use nomographs or computer software The use of nomographs not based on HDS 45 is subject to the approval of the Hydraulics Engineer 31 4 03 01 Structure Type The following applies to the structure type 1 Culvert This is one of the following a a covered structure with both ends open b a type of structure designed using the proced
91. w Type VI see Figure 31 5E b Vu is small and its velocity head can be considered to be a part of the available headwater HW used to convey the flow through the culvert c is small and its velocity head can be neglected d Equation 31 5 9 becomes the following HW H SoL Equation 31 5 10 Where HW depth from the inlet invert to the energy grade line ft H value read from the nomographs Equation 31 5 8 ft SoL drop from inlet to outlet invert ft 2 Partly Full Flow Equations 31 5 1 through 31 5 10 were developed for full barrel flow The equations also apply to a flow situation which is effectively a full flow condition if TW lt dc see Figure 31 5F Flow Type Backwater calculations may be required beginning at the downstream water surface and proceeding upstream If the depth intersects the top of the barrel full flow extends from that point upstream to the culvert entrance 3 Partly Full Flow Approximate Method Based on backwater calculations performed by FHWA it has been determined that the hydraulic grade line pierces the plane of the culvert outlet at a point halfway between critical depth and the top of the barrel or dc D 2 above the outlet invert TW should be used if it is higher than dc D 2 The following equation should be used HW ho H SoL Equation 31 5 11 Where ho the larger of TW or dc D 2 ft Adequate results are obtainable down to HW 0 75D For

Chapter 31 (English measure)

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