bridges, to verify the applicability of the simplified
method. For each bridge, the bridge-site characteris-
tics were used with the applicable envelope curves to
estimate the 500-year flood total scour. Each scour
estimate determined with the simplified method was
compared with the 500-year flood scour estimated
with the conventional scour-estimation method. A
comparison of the total 500-year flood scour estimated
with the simplified method and the 500-year flood
scour determined with the conventional method is
shown in figure 10. Perfect agreement of results
between methods is the 1:1 slope line through the
origin. The goal in the verification of the method was
to have the verification data plot on or just to the right
of the line of perfect agreement. This would indicate
that the simplified method either produced an exact
match to the conventional method or overestimated the
total scour estimated with the conventional method.
In developing the simplified method, seven
development/verification iterations were made to try to
plot the data in figure 10 as close to the line of perfect
agreement as possible, without many points plotting
to the left of the line. As shown in figure 10, the
verification of the method was successful. Total
scour was underestimated with the simplified method
in comparison to the conventional method at only six
of the bridges verification data sets. One bridge was
underestimated by more than 25 ft, but review of
the data file for that bridge indicates that the conven-
tional estimate of scour was affected by having over
7G percent of the flow apportioned to the overbank
at the approach cross section. Because HEC-18
computations are very sensitive to the amount of over-
bank discharge, the unusually high scour estimate is
because of the inappropriate flow apportionment at the
approach cross section.

Limitations of the Method

The simplified method was developed from data
at bridge sites in Illinois where conventional scour
analysis had previously been done. The following
ranges of values for bridge characteristics were present
at the bridge sites used to develop the simplified
method.
Drainage Area: single-span: 0.29 to 43.3 mi?
multi-span: 1.05 to 8,610 mi?
single-span: 66 to 5,319 fs
multi-span: 696 to 67,000 ft°/s

100-Year Discharge:

Flood-plain width: single-span: 14 to 292 ft

moulti-span: 54 to 3,278 ft

Base-Flow Channel

Width at Bridge: single-span: 12 to 74 ft
multi-span: 16 to 1,000 ft

Base-Flow Channel

Width One Bridge
Length Upstream: —single-span: 10 to 184 ft
multi-span: 13 to 1,274 ft
Bridge Length: single-span: 13 to 95 ft
tulti-span: 20 to 966 ft
Low Steel To
Bed Distance: single-span: 3.7 to 23.7 ft
multi-span: 5 to 51 ft
Channel Slope at
Bridge: single-span: 0.00013 to 0.0148
multi-span: 0.0001 to 0.011
Angle of Attack on
Bridge Pier: multi-span: 0 to 35 degrees
Number of spans: multi-span: 2 to 14
Pier Width: multi-span: 1 to 8 ft

In addition, the development of the method was
limited to bridge sites in the data set that satisfied the
following criteria.

* No dual bridges were used (for example,
interstate highways).

* The ratio of base-flow channel width at the
bridge to base-flow channel width one bridge
length upstream was greater than 0.5.

«The ratio of base-flow channel width at the
bridge to flood-plain width was greater than
0.03.

Total-streambed scour estimates from the simplified
method for bridge sites with characteristics outside of
these ranges should be used with caution.

The simplified method was developed to assist
in performing the enormous task of evaluating the
over 10,000 local agency bridges in Illinois. The
simplified method was developed in a way such that
hydraulic computations were not necessary. As such
the éstimates of scour are conservative. However,
in cases where the estimate of scour from the simpli-
fied method presents a borderline bridge instability
problem, a conventional analysis should be performed.
In addition, the simplified method should not be used
for design of new bridge structures.

Limitations of the Methad 415


Data-Collection Sheet
Simplified Method for Bridge Scour Estimation
OR USE WITH SINGLE-SPAN BRIDGES ONLY

Fiecp PantTY__CJD ¢ JT County Date_5-17-95
Structure Number_4 357 Feature Crossed DRAINAGE DITCH
Facility Carried__ 2 400N Location FLATVILLE

TO BE COMPLETED IN THE FIELD OR

FROM TOPOGRAPHIC MAP
Flood-Plain Width For 100-Year Flood 37 feet
(FPW)
Base-Flow Channel Width @bridge 23 feet
(CWB)
Base-Flow Channel Width 1 Bridge 2G _ feet
Length Upstream (CWU)
Bridge Length From (BW) GT feet
Abutment to Abutment
Abutment Type (AT) |
(Spill Through-I, Vertical With Wingwalls-2,
Vertical Without Wingwalls—3)
Cutbank Presence (CB) I

(None-I, Slight-2, Extensive-3)

Low Steel To Bed Distance (LSTB) H.05 feet

Bed Material (BM) AS

(Cobbles-1, Clay-2, Gravel-3, Sand/Gravel-4,
Silt/Clay-4, Sand/Sitt-4.5, Sand-5)

Information Entered Into Computer Program On_|O - 2G -95

Entered By__F2. WP

Estimated Scour. 5.7 ft

Figure 15. Sample of a completed single-span field and office data-collection sheet for County Road 2050 East
bridge over Flatville Drainage Ditch near Flatviile, Ill.

36 Development, Verification, and Application of a Simplified Method to Estimate Total-Steambed Scour at Bridge Sites in Illinois


49 €6-CHET £v61 oss‘s €F6T Ot6'b TH ‘Bnei9yq svou Yea Stq@ 00000950 O8e
ras CL-T96T ouon 692% auou Ted. “TH “iltade,y Te9U ¥eaFD PIEYAIO OOk66SSO 6LE
St 08-9S6T suon Sia auou PUL “Il ‘oz0qsouog mean Armanqin 49353 U22ID Ob966SS0 BLE
“TE ‘trop
91 9L-1961 suow 191 auou as qeou Areinqin sary APPHIN Fig ORS6ESSO LE
it 9L°0961 6961 oge'z 6961 Otr'z “UT BpURIEW] Tau FO2D FOYT ABI O9S66SSO OLE
99 EO TEGLGLOT‘LT-OI6L su0u O0L6e sou OOR SE ‘TI ‘cxogsAydinyy ye Joary ApH 31g COS66SSO SLE
le 78-961 eu0u 09°62 scou O0s"O7 "UL ‘smarpeyAl Teou Foor dnosneag] 00066550 Le
we £6-TS61 Suou Ost's ouou oBs*F “TIL “HOLBY Jeu YIAD PIEYDIO TAD OOSLESSO eLe
Tn “Banqentd
£1 2L-096 suou asp 196 6IP Jean ATeNLN YOU PLYYO GU OSPLGSsO TLE
£8 €6-S16T'ZT-6061 T96H OPEL 000°9Z 196961 00Z'EZ “TH ‘Preywayd 38 sa4ry Appr Sig OOOLESSO 1Lé
periesqo pucosy pepasoxe  saina ‘bey popecoxe @AIND "baa, eweU LOReS sequnN = (e¢} 6) 208)
sueek 40 poyled ‘sa COLD pegybjan sem payybjem. uones aequinu
yo'on S186), woxy- 0st GIES, wea eoueseje1
(si) COLO {8/.n) os dew
penuyueg—pepseoxe

18M SenjeA UEUM SIREA PoE|DOSSE YM SIoUl||| UE SUCH EIS BuIBeB-weens Aening (eo/Bo|o8y ‘S'7 ye sabseysip pooy 1ee4-001 pue -Og Jo epnyubeyy % a1qey,

32 Development, Verification, and Application of a Simplitied Method to Estimate Total-Streambed Scour at Bridge Sites ii



-seBpug ueds-lnw 40, ueeios dui XP HNOOSU 6} ean

39)9909 | pea
; au0N :
Ladty Gs
: —— = ees ee
—_ : :
——
aes a :
310

4

Application of the Method


aoo'cao'ocl =900'N00"O!

ty says @BpLq 40} PoE |eUOAUEAUOD OY) UIIM PETBWSE NODS BIO} 10) | eAIND EdojsAUS UedsIN “9 ANB
ex
oao'odo': op0'Oo! on0'ok 000": OL Qt t a boo
T T Trt
g
oe
e .
. . or
. in
* . ot 9°
oe a
tm
aan oz g
* =
. >
. « i
Q
7 J
Ge &
yoo} U ‘yyBue; ebpug = Ma EI]
dh} i@ld = td _
J98) UL 'eoUR\SIP pag 0} ;89}8 MOT = ALS7 <
yea} 19d 399} ul ‘adojs jauUEYyO = S ~| 5e a
UIPIM ule|d-pooy BAnsey3 = Mda
puoses Jad jee} a1qno ul ‘afreyosip pool 4204-001 = O q
| ov
2999'HEx)4 29z0°2 = A °
gMd * old
= 6X 7 oF
° gLST * 5/95 tog Mdd* 50

os

9

Simplified Mathod to Estimate Total-Streambed Scour



areca:

Date

INL’

cE:

PAN BRI

REL Saale ei oce
|

Th
Feature Crossed
Location

Data-Collection Sheet
County.

Simplified Method for Bridge Scour Estimation

E

Lid
Extensive-4)

Fl
-Year Flood

Vicinity
, ... See instructions)

Moderate-3,
5,

FROM TOPOGRAPHIC MAP
2,3, 4,

Slight-2, Extensive—3)

TO BE COMPLETED IN THE FIELD OR
Slight-2,

lood-Plain Width For 100.
Existing Scour Near Piers/Abutment (ES)

Base-Flow Channel Width @bridge

(CWB)

Base-Flow Channel Width 1 Bridge
Length Upstream (CWU)

Bridge Length From (BW)
Abutment to Abutment

Angle of Flow Attack on pier (A)

Cutbank Presence (CB)

FIELD PARTY.

Structure Number.
Number of Spans (SP)
Slope Of Channel in
of Bridge Site (S)
{None-1,

Facility Carvi
Pier Type (1
(PT)

Fi
(None-I,

Maximum Pier Width PW)
Low Steel To Bed Distance (LSTB)

9

Application of the Method

Information Entered Into Computer Program On.

Estimated Scour.

vel,
Entered By.

Sand/Gra
rt)

Gravel-3,

Bed Material (BM}
(Cobbles-I, Clay-2,
Silt/Clay-4, Sand/Silt-4.5, Sar

Figure 12. Field and office data-collection sheet for multi-span bridge sites in Hlinois.


was 0.62. This is greater than the 0.03 limiting value
also described in the “Limitations of the Method”
section.

Multi-Span Bridges

Knowledge of all the bridge-site characteristics
on the field data sheet shown in figure 12 is required in
the application of the simplified method for multi-span
bridges. Once the bridge-site characteristics are
determined and listed on the field data sheet, the two
envelope.curves for multi-span bridges should be used
to determine the estimated total scour at the bridge
site. The collection of the necessary muiti-span
bridge characteristic data and determination of the
total-scour estimate are described in the following
example.

A multi-span bridge over the Embarass River
(fig. 16) was evaluated for this example. As in the
single-span bridge example, a topographic map of the
bridge site and associated watershed was reviewed in
the office before visiting the site. The drainage area

was 16 mi? and the slope in the vicinity of the bridge _

was 0.00039 f/ft. In addition, the elevations and

thalweg distance needed for the 100-year flood
discharge computation (Curtis, 1987) were deter-
rained. The Rainfall Intensity and Geographic
Region values were determined from the graphs in
Curtis (1987).

At the bridge site, most of the other bridge-site
characteristics were determined and listed on the field
data sheet for muiti-span bridges (fig. 17). For this
bridge site, flood-plain width for the 100-year flood
was estimated at 375 ft, which is three times the bridge
length (a judgement based on engineering experience).
This simplified estimate of the flood-plain width was
used because the overbank area is very flat resulting in
ponded water in the approach fiood plain away from
the main channel.

The base-flow channel width was measured
from the left descending bank water surface to the
right descending bank water surface with a steel tape.
The base-flow channel width was 49 ft at the bridge
and 35 ft one bridge length upstream. The ratio of
base-fiow channel width at the bridge to base-fiow
channel width one bridge length upstream was 1.4,
which meets the established criterion requiring this
value to be greater than 0.5 for the simplified method

Figure 16. County Road 300 North mutti-span bridge over the Embarras River near

Pesotum, lll.

Application of the Method 37


18. ILSCOUR.EXE input screen for single-span bridges .. .
19. ILSCOUR.EXE input screen for multi-span bridges. .
20. ILSCOUR.EXE input screen for calculating 100-year discharge for ungaged rural basins using methods

outlined in Curtis (1987)
21. ILSCOUR.EXE input screen for calculating the 10-year discharge for ungaged urban basins using methods

22. Sample output from the computer program ILSCOUR for estimating total-streambed scour at bridge sites in
Wnts 2 eee eee renee e tect eee be rented tite et iti etieee etter ccs

TABLES

1, Bridge-site characteristics and associated abbreviations used in the simplified total-streambed scour estimation
method in Winois. 0... 0.6... oe eee cece eect tebe cence cee en bebe bite ecree es
2. Magnitude of 50- and 100-year flood discharges at U.S. Geological Survey stream-gaging stations in

associated years when values were exceeded .. 0.6.6... oo cece ececcceccca cece reuteatetteeteccecceeee
CONVERSION FACTORS
Multiply By To obtain
foot (fi) 0.3048 meter
toile (mi) 1.609 kilometer
feet per feet (fi/ft) 1.00 meter per meter
cubic foot per second (fi°/s) 0.02832 cubic meter per second
‘square mile (mi*) 2.590 square kilometer
square mile (eni”) 259.0 hectare

Contents iV


es €6-1P6T euou OEL'6 SP6T DL0°8 “TH “Bpueay 38 49a) URIPUT OODRRSSO see
se £6°6961 9u0u 00721 ouoU, oOc'TT “THT ‘2TTaspaempy 3 3P9FD PIYOYED OOGLESSO pEE
“Ty Bayuadres
[<4 08-9961 8SéL SEL BS6T £79. eau Z ‘ON ATeINgIN FAD VOW SSLESSO eee
99 €6-TP6T€E-1261 euow ool'z €r6l 009‘9E “III ‘suey seau yparD usdnoseA, GOGLESSO ee
SZ 08-9961 ouou ss suou or ‘IT ‘stopaay iwou AreMgLn Year sg OSEIBSSO Tee
aw £6-2661°06-1S61 LS61 Orel LS6t ator ‘ID ‘esnoypooy Jeet Aa0rD oueauINH OOS9BSSO OLE
“TH “aypadesrnyy
A) TL196E auou at0'z au0n OzLT seau Areynquiy year Apueg oN OSE98SS0 62E
4 08-9861 suoT oor amou 0z0T “TL ‘souarop,y ye ATenQMy JoaTY SIOUTTIT OOZ9BSS0 Bz
“TI “TATosyoer
ey £6°766T-06-0S61 suou ore’ O66LE86ELL6L 00e'r JBM Yoa) SUSE Ss BANCAT ae GUON GO0985S0 LE
“ID ‘Suypag
Iz 9L-9561 suo aT auou 901 JuTOY Jeau Areqnqrn y204 AI OOLSRSSO Cras
69 68-1261 anou Q00'LET euou 000'971 “IT ‘BisopasoyAl we JOATY SIOUITTT OOSSBSSO Sze
a 08-9561 uou OLL'T ouou OzS'T “TUL ‘Heqoutg reou Areinqry year) VeIPUT OZZSBSSO ze
€L €6°1Z61 uo OOS‘OE O66L'S86T 09°97 “Tn ‘Sardry ve sary OMIOW ET. NONSESSO «ETE
ral CL-1961 SuOn 8. euou rary “TIT Surpiarg UNO 42 FSI WIA, OSGYRSSO Ce
or £6-SP6L S86t 00z'8E S86t oos‘ze “II ‘reurog we seary suroyy FT OOSPESSO = «Tze
91 9L-1961 ouou Teh auou Leo. “TM ‘quoseyy wou yaarD MOTION WEMTIM OSFPESSO Ooze
cE 76-1961 O86T Ome O86T 006% “TL Taugsag 1 oy BuMorq OorPSSSO 61
£6-TE6L67-9761
OL SOZ-1Z6TBIT-SIGTZL-O16T ep 00L'08 4 o09'TL ‘TIL ‘PIOPAEO Ieau Ary vOUTesueS GOCESSSO SIE
we TS-OS61 eugu O1o'T suou 6L8 ‘IMT ‘Torseg swou Year auer) OOSZBSSO Lie€
TH ‘Sunqaiajed
154 9L-OS61 $9 oor't so £98 eau ArengIn YAstD ssaulqed COTZBSSO ole
ws £6-Th6T suor 006'9r ev61 008'Or ‘TH ‘mopatroar Iweu ysezD Yes OOOTSSSO STE
8P T6-SP61 7861 oos‘9¢ E861 1861 00262 “TT ‘Sungsuex Jeou yaar) Awsng OOSTSSSO ple
61 €6°SL61 £861 osr'9 9861°E861 ose's “TIE ‘uoyuTMIOOTg Jeau 4Or] ENS OS60RSSO ele
or 9L-1961 1961 Oz 1961 668 TI teosarppypl ie Aemquy 4aaID BS 00L08SSO TIE
SP Z6°SP6I suow a0Pte P86 6LET 000°07 “TIL ‘Ujoour'] seau years oodeysry QOSOBSSO Ile
oF €6°8r61 1861 08°22 186156261 09°81 “TI ‘oIAsaudeyy 1 YoarD oodeyory 90008SS0 OTE
SE €L-9S61 9561 OtL'T 9S6l Oe'T ‘TH Yuomday ae Arwingin Yoox) oodeyory OSL6LSS0 60€
uy €6-RF6TEb6L €r6l OOL'ST Ebel 009°%T TI ‘PUBTWIOD AOU YIOT BAT OOSGLSSO BOE
9s E6rEFET‘ZI-BO6L * 8961 000°2Z 8961 000'81 “II ‘Tasoy Weeu year WBS NOSRLSSO LOE
Sz 08-9561 anou 996 auou frag ‘ITT erpuy ve Arenquy Jsary woweSuEg NOLLESSO 90g
peasesqo pucoe pepseoxe ening “bez pepesoxs rund ‘bad eWweU HORS dequinn = (€1 ‘613 898)
sueeA JO payed BBM DOLD payyBjom ‘SEM peyyByem YORFIS: dequinu
jo'oN ‘180, wol- Ost suze, wlos~ eaupieye.
(s/,4) GOL (8,8) 090. dew
Penuyjuog—pepeeoxe

@JeM SAN|RA UOUM SIBOA PE}EIOOSSB UY S[OU]] Ul suones BulGeb-weess Aansng jeo6o}ae5 °$'n ye seBreyosip poo} 1864-90) pue -og jo epruBeW ‘Zz eIGBL

30 Development, Verification, and Application of a Simplified Method to Estimate Total-Streambed Scour at Bridge Sites in Illinois


“slot

uy sey1s eGpyq Joy pounaw peyriduuys eu) YL

peulwuetep inoos pequraayys-(8}0) perswuljse pure Poyjew jeUoNUEAUOD eip YM PEULUWEIep 4NODS peqweeis-jelo} peyeumnss “of esnBly

1334 NI ‘HNOOS OSLVNLLSS COHLAW OSuMdis

ov se os ge

4 gh

oF s te}

“\ueweaiBe yeyed jo eur

saBpyg peumg Awnog uedg-e[buig o
sefipyg peumo eyeig uedg-e|6uig v
sefpug peung Ajunog uedg-ninyy =

seBpug peung eyeig ueds-lIINN +

+ SE

SP

13343 NI ‘UNOOS GALVINLLSA 8l-OFH

16 Development, Verification, and Application of a Simplified Method to Estimate Total-Streambed Scour at Bridge Sites in Illinois


1g £6-0661'98-0P6T auou 0os‘IT quou 03866 TUL eH 1 ¥891D THA O008ErSO 06
8g £6-9C61 suou 006*€ET suo 00g'Z1 “Ul ‘ossouay Jean Jaany Wea OOSLPrSO 68
OL 94-1961 L96T ISB L96E gle "TIL ‘vosuppy eau Alemqu) Ya1D PNT ASELPYSO 88
oF IL-9S61 auom 9EL suon eet TH Apaeouon we YONG ApuBWION OZLESO £8
+ CL"6S61 auow OLL suon £99 “TH ‘O1GQ Twou Z ‘ON Areingin JaaTy ueeID QSOLPPSO 98
ey 28-061 186. O6S‘L T861 0s6'9 “TH ‘Aoqury 38 494TH U9AID COOLPrSO SB
ol SL-196T auow SSL euou £09 “Ty ‘Aoqury se2u Alemnqun J9ATy UeetD) OS69PPSO 8
$s £6-0r6T suor o0s‘09 au0n OOT'ss ‘TH Utsor Jeau Jeary YOU OOS9PbSO €8
8? €6-8L61-1L-0F61 OF6T oza's 9b61 ost's “IT BOsPUOYy 18 499d} YOY OOO9HHSO sy
vai TL-6S61 uom oor'l stow 186 TH B9[0D eau Areingin yer Burds OOTyPrsC 18
ss £6-OF6T'8E61 su0u 0964 enou O9zL ‘TI ‘ssoruag seau yaar Wout OOOPYPSO Of
OL ¥6-1661'98-S161 £461 Q00‘6s ELOT 009'rs TH owoD We Joarg ON OSE PPSO 6L
ZL 1S-OF61 uu 0z0'r suo O8s"e “TH Towed SBepy seou toa su OOOHPSO BL
al 6P-OF61 en0u Q0E'r9 Suou OOELS “I 'UodaIO 1 PANY oY OOSTPPSO it
4 @8-OF61 snow Oor'el Suou 009'0T “HL TOaTy Jeo] 4 Jaary Jee] OOOIP PSO OL
14 6L-9S6T au0u ole Su0u 097 “TH ‘wowsauioy Jeu Areinqua ZoATY Je 00607rSO SL
TH ‘quiosoy
ar 9L-6S61 enou £6£ uou Oe eau ATRINGLN Yeas UBS NS90PPSO bi
It 08-0F61 suou ores ouou O16'L “TM Faqwap soquoyy Jesu 49909 JONAH OOSOPESO gL
8 £6-OF6T suo os‘ suou 006'TZ “TN ‘oittadareg seau Jeary aayneAystyy OOOOKESO th
“TH ‘ouaq] seou
gt 9L-6S61 suow OL auou €6s Arenqun Jeary ooyNUaysry PouBlg YING OSSGErSO ‘te
“UL ‘ereprred
$s €6-0P61 suou oor‘oT uOu OLS'6 FOU JAR SOYNBAYSEY WUE WINGS HNS6EPSO OL
“U1 ‘9rex 2
ww £6°0R6TIEE-9ZET E861 oor'e £861 O16 Je TAATY sayMUMISTY TOU MOS OOOSEFSO «69
TO exe Jesu JOATY soynEMysTyy
st 08-9561 uD 1s ouou ose Youerg tpnog Jo Yoursg aPPIAN OSBREPSO 89.
Ss £6061 Suou 009'ST ouou 009°ET “Il ‘areptajag se Joary saqnUmysry OOSREPSO “9
"HT ‘uordeg seou.
OL 6L-0L61 euow 090°S ouou ols'p YS} JaPOYO MOTAQ YBa MESEISI OGESEPSO 9
“10 ‘prearey
0t O8-T961 Su0U ose eucu £0€ Jeou ArEINgIN AAD BoUstMe] QOEBESO sg
Of 16-2961 8261 08s‘ 8261 Oger TIL “APIPa 18 JOE HOOD OSZREPSO hed
ial BL°S96T au0u PIE auou 062 "HL ‘Aopuny Jeu JoATY SOyNEAYSTA OS6LEDSO 9
or 9L-1961 auow 619. auoU eps ‘TIL ‘uonyooy eau Areingin yaany 490y O09LEPSO is
59 €6-OPG6T*LE6T*6T-S161°80-P06T euou 009°9E quou ooe'ce “HE Worjooy ye JBARY YOY OOSLEPSO 19
pasiesqo picoes pepesoxe  eaind ‘bey Pepesoxe enna “bay SWEU LOIS Jequinn § {e} "By 3e8)
sue0k Jo papeg SBM OOLD peyySjom sem powy6ien. uonels Jequinu
JO"ON SIBOA wou- 050 BIE, Woy eouszajel
(8/3) OOLO (qu) OS0 dew
panuljuog—papeeoxe

@JOM SON|BA USYM Bleed PayeDoosse LIM sioulp| Ul SUCHEYS BuIbe6-wweexs Aerung jeoBojoe *g'n ye sefiseyosip pooy seeA-9O} pue -9¢ jo epnyubeyy “Zz aquL

Development, Verification, and Application of a Simplified Method to Estimate Total-Streambed Scour at Bridge Sites in Illinois

22


16

Data-Collection Sheet
Simplified Method for Bridge Scour Estimation

Fi H LE-SPAN iE LY
FIELD PARTY. County. Date.
Structure Number. Feature Crossed.
Facility Carried, Location,

TO BE COMPLETED IN THE FIELD OR
FROM TOPOGRAPHIC MAP

Flood-Plain Width For 100-Year Flood feet
PW)

Base-Flow Channel Width @bridge feet
(CWB)

Base-Flow Channel Width 1 Bridge feet
Length Upstream (CWU)

Bridge Length From (BW) fect
Abutment to Abutment

Abutment Type (AT) ——_

(Spill Through-I, Vertical With Wingwalls-2,
Vertical Without Wingwalls-3)

Cutbank Presence (CB)
(None-I, Slight-2, Extensive-3)

Low Steel To Bed Distance (LSTB) feet

Bed Material (BM)

(Cobbles-1, Clay-2, Gravel-3, Sand/Gravel-4,
Silt/Clay-4, Sand/Site-4.5, Sand-5)

Information Entered Into Computer Program On.

Entered By.

Estimated Scour,

Figure 11. Field and office data-collection sheet for single-span bridge sites in lilinois.

Qevalopment, Verification, and Application of a Simplified Method to Estimate Total-Streambed Scour at Bridge Sites in IMlinols


rag TL-9S61 ouou DE0'T euou £88 “MM Soren 18 Arsinguy yooID Apuy 00196560 OLE

St OL-9961 196 009'Se 1961 06°67 ‘JH ‘uoqueg raw saAry Appny Sq 00096550 69€
(44 78-1961 ° euou Obb'e euou OEO'E “TIL woWaA "AI TOU Yoary o[MUUIASS OORSESSO ROE
St EL-6S61 ouau 969. ouou Le “TN JoqsauD We Areynqun Joaty shrew, OSSS6SSO bE
al TL6S61 suou Oor't uou 186 “TH ‘Bopg Jeou young Yr] OTSS6sso 9BE
ca 1L-6r61 ouou osa's 8961 o19'9 “yo ‘vameds sean saary skmmW OOSSESSO soe
ve £60261 auou OOrtt €L6T 000'ST “TIL 429H WWoU YSarD PUTYTA GOZSESSO vOE
ius TL-SE6TTZ-SIGUET-806L quou 000°60T euou 006°%6 TIL ‘StstpY aN Je Jeary EPISEYSe MY OOOSESSO €9€
£% E61 LET ouou 000°07 ouou OOL'LI "TH “Binqoos,] eau FoadD Teas OOSPESSO ZOE
[x4 €6-L961 ouoU 000'ST suou Gore! “TL Aor] eau FaauD Joayis OSPhOSsO 19€
4 T8-1L61 suor 0026 su0u ocee “TIT “BsspeY] Jwau Year PR OLEP6SSO O9€
ral CLOSET auor ort qu0n O71 “TH ‘S8pIOD Tusu YTD SWRI, OOZPESSO 6SE
ol Z8-EL61 quow oor'el ouow OOL TT ‘II ‘stoqry We yer IesNS O6OPESSO BSE
es E6-OPETEPET-EL-O1L6T £P61 o0z'se £¢61 O0s'cE ‘Ill ‘aseoug Jeu year [ROUS OOOPESSO ESE
OE €6-7961 SuOu 0289 i961 opo's "TH “uoayjo> swan 3eerD [Roys WoO. seq] GOGEGSSO Ose
“TH puowsey
el 14-6561 au0u €8e, 9961 BEE eau AseingiT] Y9axy SsBIE AN} OOLEGSSO SSE
Te 16-1961 ‘on0u OLP'Z guou OSZ'Z “UL ‘puowsAey Iau YseI9 ssBID INI] OO9EGSSO PSE
“TL UepoTA
Ey4 £6°8961 auou oor'et 0661 000'TT ANON JEU YOK] PEFOOD OMIT SLEEESSO ese
or e6-Si61 0661°9861 oos'st 06619861 006'ET “HI ‘UeuEZOH Tee Jaa PIyoaID OZSEGSSO cas
OL €6-OLG6EST6I‘Z1-806T Suou 0086S €p6t oOs'Ts “TH ordre 2 s0ATy eRYseYSEY OOOEESSO TS
& 6-116] suou OOr'1z ouou 002'61 “UT ‘aarp Azroqinypy rau yser) sTuOKINH OO8TESSO ose
St 08-9861 ‘SuoU ist eu0u evr “TH SAA seau Areyngry Ysaqy euETUNH OOLZESSO GbE
£8 €6-CZ6E'OZ-ST6LZ1-8061 Ls6l O0L'8S LS6TSOSELEPEL 000'6r “TL Plepura Je Jeary BLySeysE, OOSZ6SSO Bre
¥e 78-6561 ouou 098°6 auou 069°8 “WL ‘AD sayoveg Tau yaar) JOM OOEZESSO Lee
itd 9L-9S6t ouou ess euou SSP ‘TH ‘TH Jamo zeau Areinq¢n ¥eerD PAW $ZOZ6SSO Oe
09 £6-1F6EGEGTET-8061 ouou 006'7E su0u 00262 TH ‘aTAdaqays 1e See aceite 00076sS0 She
“MAD aye T
0% 08-1961 euou 91Z. auou O6T Teou Arangin Youerg UMOIUINS OSL 16SS0 bre
(<3 Z8IS6T ouou OT pLérT ral “II “Wearing 18 Year> BSY OOSTESSO ere
&% €6-1L6E suou 00Z‘E1 auoT 00021 "TH SIA SYOOD 1 JoARy EDISEYSeH COTTESSO ChE
4 E6°EL6E auou o1s's auom OLl's “TH ‘poomay 18 Of BIBT CORD6SSO Te
W bO-PS6T suon OsL'9 ou0u OP6'S I] WAPOA Ye JOATY EPYSeYsey OOLOGSSO Ore
$1 6L°S961 Sun Ors'y su0u oor'y “TIL “mmosog Jeau JoATY BryseyseyY QOPOGSSO GEE
oF 06-6661'L7-PZ6T au0n OSé'T ouou 079'T “Hl “olrapuog yw Usit ERIseyseyY OOKOGSSO BEE
“EL OTASUIIIOD
bal CL-6S6L ou0n ose't ouou 060T swou AreingyR 49axy UIAIUED INIT O8L68SS0 Lee
oP PS-6E61 ES6T‘9P61 one's LS6V'9P6L 0s6'9 “TI ‘afiadase;) 48 Yaar U9DINED OS6RSSO ose
paaiasqo Ppioses Pepesoxe ano ‘bel, pepssoxe enna ‘bey BUBU UORRIS soquinn’ {e) “By 998)
BuRGA JO pojeg 88M OOLO payBjen oem peyyijem uopas aequinu
jo'on 188), wOdj- 65D s1e0, wedj- eauelejei
{o/,4) COLO (s/,y) 090 dew
penuyjuag—pepeeoxe

@18M SBNIRA LEY siBeX payeloOssE UM soul! UL sUOITe)S Bu\Beb-wee.s Aenung peojbolaery ‘S'7 18 seBreyosip pooy, yeeA-00| pue -og jo epnyubeyy ‘% B1qBL

E32)

Application of the Method


/__ High-water line

Section 3

=i |_|

Plan of abutment

I

Downstream elevation

TYPE 1 - Spill through

Without With
wingwalls. wingwatle

Downstream elevation

TYPE 2 and 3 - Vertical with and without wingwalls

Figure 9. Abutment types {adapted from Matthai, 1968) used in the simplified method.

Simplified Method to Estimate Total-Streambed Scour

3


ro

1a33 Yad 1334 Ni ‘AdO1S TANNVHD

400

400°0

“SPOUT Ul SBUS
aBpug 104 pooy J264-Q0g © 40] SpOYTel {BUOTU@AUDD YIM POUILWEYSp Neos peyeLuyse PUP eGpugq ey) seeu edojs jouusyg “e aunty

4000'0
[+

of

1434 Nt ‘SDUVHOSIC Hv3A-00S 3HL HOI UNODS GALVWLLSS

5

Simplified Method to Estimate Total-Streambed Scour



‘TH ‘woIsurw00 Tg,
£4 8S-Fe6T LP6T 0z9'¢ LP6l oor‘e OyP'] aange Hoa AVS OOSPISSO SLE
St 78-8561 suow oor'e auou Oz “TH epuemoy seau oer) ASU, OOPFISSO i7a4
1g E6-Er6T PL6l oos'se TR61‘FL6} ont'6e “THT Bi09q 38 YaerD OodexoTY OOSEISSO eLe
‘I ‘oodexory,
:s4 08-9561 6861 622 6561 cai Jean Areingen 432K) OOdvYOTY OOTEISSO tLe
ar €6-SL6T‘SL-Sb61 ouou o06‘ee suou 05°87. “If ‘codeyary seou yor3 oodeyory OODESSSO 1k
gE O8-€F61 SuOu OGEEZ Ly6l 008°8E “TH “Buoad 1seq Je Yea WIRY GOOZISSO OLz
8g S8-BP61 Su0u 389 enOuU Z19 ‘ITT “eHoag seq Jeu Yoox) Oe|npuoy OOST9SSO 697,
[x4 O8-FS61 O86l ols‘ 0861 OtL'E “TH ‘aTepune,y re Joa eWay OOOLOSSO 897
oF S8-1S61‘6P6L Suou OLO'L Og6T £66 IM ‘sjepuuse,y 38 FIaI UAT OOSOISSO L9@
Le 6£-E06T Suou 005‘89 euou 00869 “TD ehoag Je Jeary STOUNTE O0009SSO 99%
8€ ta-Seol euoU 0L8°9 auou oso'9 “TY ‘tungyseAA TeaU Yer MOI NOSGSSSO Sot
Le 78-9P6t uou 009°% suou oce'z “TIL puepreds re ye01D WUD 0006SSSO 97
€f z8-0S61 guou ores QL6T ozs “HL “ATueH Teau GS9M) HAD MOID OOSESSSO £97
144 O8-6L61°LL-9S61 ouou 66E ‘SS6T £ce “WIT ‘updenuey wou engin yeaxD 2aYOD SLOBSSSO wt
x4 9L-9S61 ouou OET 8561 <O1 “TL PROD sou Arengen yoarD sayoD OSOsssso 19%
IL TS-1P6T suou O0S"Ez suoL 000°TZ ‘TIL ‘heaing ye FaauQ neang Sq G008SSSO 09%
9s E661 16LE61 ouou O16 uon ose’s “TIT ‘neaing eau yaar nealng 3seq OOSLSSSO 687
“TM ‘SOUBK A
144 6L-9S61 Quou tLe su0n WOE wou ATANTN Yaary MBAINT SOA OOTLSSSO 89e
Ss T6-LE6L ¥L61 009°Z1 PLOLZL61 O0L‘0I [UN “Joued py Ye Yoory neang wa, OOOLESSO LSt
us €6-LE6T auom oor suou 000'ET “TH ‘oyaourg te yeas neamg 3g OOsossse 9st
¢L TL-6S61 su0u gst 000 SEL “TH ‘vepLeyA 1e Aremgrn ysery UORMUAA SELSSSsO St
4 9L-9S61 su0u 962, erou 9cz. “TIL T2Mo7] 3 Areyngin reaTy woTTIAA GOPSSSSO PST
£9 €6-1E61 suon oor‘es ou0u QOL ‘FE ‘TIL “sz0U0e7 Jeou Feary WOTTIEA QOESELSO est
or O€-ST6I euoU ooL'ez eu0u 0e'1z “If Jowang ye Joary UOTTIULIEA OO0SSSS0 374
81 9L-6S61 eu0u LOT suou Oat “TH ‘TPC swau Aremnqun 42215 PRL OOSPSESO 4
1s £6-P961°29-EP6T-EL61 anou 009°ST ouou 000'FT “III ‘Sep 18 Joan UOTMEIDA OOSPSSSO Osz
“I enopwey
1g £6-Eb61 Suou 006'9 ouou OFz'9 JOU JWATY WOTMULAA YO YON OOOPSSSO 6b
8h £6-9Z6EPZ-SI6T Ss6L O0E'8E Sse O08'Ee “TE ‘WoVMec 38 JOATY XO ODSZSSSO 44
91 08-S961 euou 188 9uou €6L “I “You Big sesu FeexD UTA OLGISSSO Lez
“In 00U Be
SI 6L-S961 suou OEL'E PLél OPs'T seaU Yoar Joy Hq youelg eT OG SSs0 Ove
pealesgo Piogas papeeoxe  enino “boy Pepesoxe rund ‘bay WRU ONS Jequinn = (¢1 ‘By e286}
eiBak {© poned seM OOLD payybyam, oun pajyBjom wong dequind
JOON ‘sIBeA, wosy- 0g SIE, wo~ eauauee1
(ig) 0010 (eu) oso dew
panuyuag—pepesoxe

819M Senjea USYM sIBek poyBIOOSse UIIM SiON]; U| SUCHEIs BusGeB-weens Aerung jea1Ho}08H *g'f) Je seGreyosip pooy 4eeA-NO1 Pue -Og jo epnyubeyy “Z eIGeL

Development, Verification, and Application of a Simplified Method to Estimate Total-Streambed Scour at Bridge Sites in illinois



4 £6-SP6T L861 OCe'1 Ls61 Ozr't AN ‘siqBIOH OSeITY> JOU Ysary 109 SEZIESSO ser

Lad £6-0S61 oom ative ‘suoD oz8'z “IE ‘poomuap ye Joa Woy] SIZIESsO ver

ST 6L-S961 euoU 099% Suu O8e'z TL Sy8t9R OFeaTYD eeu Ried tag O1Z9ESS0 €aT
“TT ‘s1y8eR

gt LL 2961 8961 Ov0'r 8961 898 oBeo[YD we Ameynqu YarD WOUL LOTIESSO 781

at BL-Z96TLSETSSEL Suou E8'T euou ogr'T “TIT 3ssuo se 1B Yat WoL, TOZIESSO 18h

ey £61961 L86T:L96T OLU'z LE6T+L961 020% “TH ‘SUN Te soary OdvonAD youRIg TON OONSESSO ost
ee)

iy 4 61-0961 L961 One 1961 Ose'T KOHOW 18 Jeary OFBI1YD Yours WON QORSESSO 6LT
“TH Maraua[D 18

BI LL-0961 suou Otel ouou OCZ'T JOARLOSWINGD YOURIG YHON JO Wa AA, OOLSESSO BLT
“AI AOorquPION 12

tp E6ES61 2861 OcI'T L86UZ861 O€0'T TOATY OBeOIYD Youerg THON JO WOT NOSSESSO iil
“TH “Pleyssaq 38

91 9L-T1961 euou 8e9 auc 109 ToATY OBeo1tTD Yours YVON JO FOT SSA OOPSESSO SLL
mig AUNgyaouUEg Te

eat 9L-1961 auton or anu LU JOAY OFvoRID BauELG WON JO WoL WAM OOESESSO SLT
“TH MarAUaTD

3 LL-0961 rou Orel 9161 O1eT ye soaTy OBeo1y> YouU_ YON OOZSESsO Las

0% 64-0961 suou L6S L961 Los “JUL ‘PISUMMON 18 Jeary SPIOYS OSTSESSO ELT

te £6-L96L 2861 £08 L861 yeh TN ed puRLUsTH Jesu FART aP|OAS OLOSESSO tL

ow €6-2S61 9861 €8p 9861 SPP “IE ‘ISat0,J Dye] 32 JOARY IPOYS OOOSESSO 1

$I 9L-C961 auow 165 ouon ces “TL SUNT ONE OANT SPHOAS OOSPESSO aLt
“TH ‘PYTHON

it4 08-0961 auou £09 enou les ye Joan OBeaTYD youerg YON OO9PESSO 691
“TH ‘Prleysaq

a 6°ES6T L861 £82 L86U'Z861 60L qe JOATY OBkOIND YOUBIG PION OOSPESSO a5
uINqyoOUTE

ral 94-0961 ouou ose auou cer ye JoATY OFBd1YD Touesg THON OOPPESSO LoL
“HI aso] ET

or 92-1961 auon 60P auou Oe. ye JoALy OB¥aIYD yours YON OOEPESSO 99t

ae peS16t auou Oze'9 enon ozs “TW ‘ourey Je Jeary SaUTE]d 59. OOSEESSO Sor

a €6-986T'6L-196T 0661 oEg'! £661°0661 o0s'T “quowiy’] Jeeu OOK) [TIME OOPEESSO vol

st 9L-¢961 auou agT suou edi ‘ABPLPOOA Je2T Y9II SPIE ODECESSO 91
“TM ‘OUEAIPSEL

61 6L-1961 9uou SOE auou 6bE eau Aremnqin YIUD RIMES OOTEESSO zl

ve £60961 euou 000'E 1961 oss? “UL ‘sdundg moma, 90 y2auD Fe] OOOLESSO 191

peniesqo prcoed papeeoxs  evuno ‘bey Bepecoxs a@aino ‘bey seu UOHES sequnn = (4 "iy ees)
samoh yO poled sem DOLD peysjon SEM peryBjem uopels sequinu
yo°oN wee, wddj- GSO see, wos soueiajor
: {8/,44) 0010. (eg) 090 dew

penulyjusg—pepeeoxe
olem senjea UeUM SHeBh Payeioosse YYM S}OUl|I| UI SUOHEIS BulBeB-weans Adrung jealbojoey "S118 sobseypsip pooy 1264-90) PUB -0g JO epnyuBeyy ‘Z aygeL

Application of the Method 25


the necessary computations. The Illinois Department
of Transportation is analyzing all State highway
bridges by applying conventional hydraulic and scour-
analysis methods (more than 500 analyses have been
completed to date (1995)). However, complete
hydraulic and scour analysis of the more than 10,000
local agency bridges (those bridges not owned and
maintained by the State of Hlinois) is not possible
because of financial and personnel constraints. The
U. S. Geological Survey (USGS), in cooperation with
the Illinois Department of Transportation (DOT),
developed a simplified methed to estimate the total-
streambed scour at local agency bridges to assist in
addressing the FHWA mandate. - Total-streambed-
scour envelope curves are utilized in the method.
These curves relate total-streambed. scour with easily
obtainable bridge-site characteristics. In this report,
total-streambed scour is the sum of the local and
contraction scour only, Very little hydraulic informa-
tion is required in the method and the analysis can be
completed in less time than the conventional method.
The method offers local agencies an economical tool
to analyze bridge sites for total-streambed scour. The
tradeoff in time saved is that the estimates from the
simplified method may be significantly more conser-
vative than scour estimates from the conventional
method.

This report describes the development, verifica-
tion, and application of a simplified method to estimate
total-streambed scour at bridge sites in IHinois. The
method was developed from 213 bridge sites for which
conventional total-streambed bridge-scour analyses
had been done by IDOT and verified from 106 and
15 bridge sites for which conventional total streambed
bridge-scour analyses had been done by IDOT and
county highway departments, respectively. The
method was applied to two county highway bridges in
central Hlinois, which are included as examples in this

report.

SIMPLIFIED METHOD TO ESTIMATE
TOTAL-STREAMBED SCOUR

Development of the Method

In developing the simplified method, the main
objective was to relate some combination of easily
obtainable bridge-site characteristics to an estimate of
the total-streambed scour resulting from the 500-year

flood discharge. A further constraint, at the request

of IDOT, was that no hydraulic computations would

be necessary to use the simplified method. The

bridge-site characteristics would be obtained from a

reconnaissance-level bridge-site visit, 7.5-minute

topographical maps, and bridge plans. The method
to estimate streambed scour was initially envisioned in
the form of a multiple regression equation or envelope
curves of total-streambed scour.

More than 500 State highway bridges that had
been analyzed by IDOT personnel using conventional
methods were screened based on the following
criteria;

1. Sufficient site-characteristic data were available in
the bridge-site file.

2. The bridge was not part of a dual system of
bridges (being either the upstream or downstream
bridge) because the hydraulics of dual bridges
would be dissimilar to those of single bridges.
Most local agency bridges are single-span bridges.

IDOT is organized into nine geographical
districts. To attain a good spatial distribution of data,
an attempt was made to select an equal number of
bridges from each district (approximately 30-35
per district). On the basis of the above criteria,

319 bridges (fig. 1) were selected for developing the

method. These data are contained in a computer file

listed in appendix 1.

For each of the 319 bridges, characteristics of
the bridge site, easily calculated or measured from
either the bridge plans, topographical maps, or a field
visit, were determined and compiled in a data base
along with the estimated total-streambed scour result-
ing from the 500-year flood. Of the 319 bridges,
213 were used to develop and calibrate the simplified
method to estimate total-streambed scour. The
213 bridge site data sets were divided into multi-span
and single-span categories (124 multi-span and
89 single-span). The remaining 106 bridges in the
data set were utilized to verify the applicability of the
simplified method.

At the beginning of the development of the
method, several attempts were made to develop a valid
multiple linear regression (MLR) model to estimate
the total-streambed scour resulting from the 500-year
flood discharge. After 40 MLR model trials, the
model calibrations for both multi- and single-span
bridges resulted in correlation coefficients less than
0.6 and a model fit through the center of the data,
which would mean underestimating scour calculated

2 Development, Verification, and Application of a Simplified Method to Estimate Total-Streambed Scour at Bridge Sites in Illinois


Development, Verification, and Application of a
Simplified Method to Estimate Total-Streambed
Scour at Bridge Sites in Illinois

By Robert R. Holmes, Jr. and Chad J. Dunn

Abstract

A simplified method to estimate total-
streambed scour was developed for application to
bridges in the State of Illinois. Scour envelope
curves, developéd as empirical relations between.
calculated total scour and bridge-site characteris-
tics for 213 State highway bridges in Illinois,
are used in the method to estimate the 500-year
flood scour, These 213 bridges, geographically
distributed throughout Illinois, had been prev-
iously evaluated for streambed scour with the
application of conventional hydraulic and scour-
analysis methods recommended by the Federal
Highway Administration. The bridge character-
istics necessary for application of the simplified
bridge scour-analysis method can be obtained
from an office review of bridge plans, examina-
tion of topographic maps, and reconnaissance-
level site inspection. The estimates computed
with the simplified method generally resulted in
a larger value of 500-year flood total-streambed
scour than with the more detailed conventional
method. ‘The simplified method was success-
fully verified with a separate data set of 106 State
highway bridges, which are geographically
distributed throughout Iilinois, and 15 county
highway bridges.

INTRODUCTION

Bridge failures are most commonly caused by
the scouring of the streambed from around bridge

foundations during floods (Richardson and others,
1993). All bridges over waterways in the United
States must be evaluated for the risk of failure because
of streambed scour (Thomas O. Willett, United States
Department of Transportation, Federal Highway
Administration, written commun., 1991). Each
bridge must be rated on the basis of Item 113 of the
National Bridge Inspection Standards (Code of Fed-
eral Regulations, 1992). The Item 113 tating is
assigned by determining the stability of the bridge
structure when the streambed is subjected to scour
resulting from a flood of either 500-year recurrence or
1.7 times the 100-year recurrence interval (1.7 times
the 100-year flood discharge is recommended in Fed-
eral Highway Administration (FHWA) Hydraulic
Engineering Circular Number 18 (HEC-18) as a rea-
sonable approximation to the 500-year flood peak dis-
charge), either case will be referred to as the 500-year
flood in this report. For Illinois streams, the 500-year
fiood discharge regression relation determined by Cur-
tis (1987) essentially ranges from 1.25 to 1.3 times the
100-year flood discharge, which indicates that 1.7
times the 100-year flood discharge is more conserva-
tive than the method outlined in Curtis (1987). The
500-year flood scour has typically been estimated con-
ventionally from equations contained in the HEC-18
manual (Richardson and others, 1993). The hydrau-
lic information needed in the HEC-18 equations is
determined by simulating the bridge-site hydraulic
conditions using computer models for estimating the
lateral water depths and velocity distributions for each
cross section in one or two dimensions.

The conventional hydraulic and scour-analysis
method is time consuming and expensive, requiring
field surveying and extensive office time to complete

Introduction = 1


“G-antsuarxa Jo ‘g-orerepow ‘Z-7y37s

*|-ouou) inoos Supsixs Jo JUNOUTe oI Jo woUssassE SATIZOIQNS & ST SIL, “SITEMSUTM JO
syuourjnge ‘sroid ay) 32 Inoos a[quaariou Jo ‘Aue JT ‘gougep oy) ‘uoTIoadsuy ays TenIsIA & WOT]
“oplag oy Jo yrpIn said wnTUTKeWu af,

“ols oBptiq ay) 38 uasord sueds Jo Jaqumu OL,

“(ag “By 208)

sord o8priq ayy oeduyy [11 Spooy SurMp Nog Oy Yor As 1 ‘soasSop U1 ‘jue oyeurutopald ayy,
“@]BUIASO INOS PANVAIOSUOD ISOW SU] UT SYNSAT Tey adky rod ou) ‘xosra-pue-peny Aq

«suaid Jo saddy aydnyynar quia saSpuqiog “(ag “Hy 398) oBptiq ay ye quasard sod Jo ad Ay ayy,
“aus o3piiq atp mau ‘yay 19d 1293 ut ‘adoys jeuUwYo [Poo] HULL

“(g- pies “gy -apisypures “p—AepopTEs *p-jaawsB puns *E—jeawa ‘Z~Ae]9 *[—s919909) uonsadsuy
JeNsTA B WONT PAUTULIOLSP PaquiBalts oy UL quosaid jewayeu poq jo odA} ayeuTUOpald on,

“(g ‘8g 208) jauTeyo-paa

regu uogEAs PD paquiwans Ueoul aetuTKordde oy pie GsIg SoufINS TEM SUIS ON] IFUOO

01 S8paq ap jo wed yep) oBp1sq 213 Jo J9qUIeUT [somo] BT) USSAIAg “Jeay UY “2ouesip oYL
*(g-Saqsua}xa 10 ‘2143s

*|-auov) juasaud SUNS Jo TENOUTE yp Jo JUSUIssassE sarjoalgns @ St SIRT, “sAuRquTEans

Su UL Tasard Sumo Jo jUNOWE aq ‘sys SBE o1p JO uonoadsuy peNsIA B UOR]

“(6 ‘By 208) ‘E-STTRASurn INOYITM SyUSUINGR [BOTA *Z-STTRAZUIA UIT SUSIE

fearon *T-squsunnge ysnoryp [ds saBpuq oy) 1 quasesd st yetp JuSUTINGE JO od UL

+(g “By 20s) juswange 07 JUAUTINIGE Wody 199J Uy “wy3uz] odpug su,

“(g “By 098) oBprig ous ye yueq

Suypraosep 149] 0} YULQ Tuypusssep YS Woy ‘3993 UT ‘JoHUEYS MOY-esEq Ol JO UIpIM FEL
“(g ‘By 208) s8puq amp wor ureaysdn yySue] aBprig suo wreajsdn wy8ua] a%piq yueq
Suypusosap 12] 01 yueg Turpuoasep syS11 wWosy “Jo0} UT ‘ToUUEYS MOY-aseq St JO MPLA don ayy,
‘yesn amp Aq pauinbar s}

”(g ‘By 29s) yppias wrefd-pooy aApoayye ou Jo ONTEA STP Sunoojes uj wowSpnliseg = “PryeA STP
Jo-asn ayy yioddns 07 ojquyreae sr elEp sANTUySp OU UsnayyE ‘sus, 93piq oy salH ¢ st paan
Usyo onyea uQ “WAPI UrEfd-pooy aarioayja atp aujwW9}ap 03 SnfeA qUEISTOI e 4q paydpyner
Buyuado pFuel-23pisq ayp posn sauiTiatwos sAeY Sisouldug «“SUTUOVOp OF I[MOYsTP saTupauT0S
St anfBa STIN ‘TONRUAOIN AA MMIPAY PaTTEIOP MOWPIAA “UNpHAs Breyd-pooy aanaaye ou JO
ped pasepision st Suruado o8pirq oy y3nomp Supasooad pue Arjso[an autos 1e Buy MOT JOB
Sururequoo uteyd poog ay) Jo ed ay Apu “MOPSAG PEOI WIM SSB JO] “Sujuodo a3piiq Ip
usnomp Suto admeyasip poo 1e24-99] 37 Supnp 11 Burddoyaao AjaojaA OUTOS JOUTIEA
aay pinows 11 ‘aepuq ay} wory weansdn upSupy eBpyiq suo ‘ured pooy ap jo Tpplas sy
“puoses rod yay o1qn9 oye syqun

aH, “(6L61 ‘yooh pur wally ‘zg6T “sHND) suonenbe voyssasSer Aaaing eO180]03D ‘S11
‘2tj Aq POUnULrolap aq Des OnTRA siyy ‘SUMUANS STOUT! 10.5 “teak uaAl® Aue ut Supango0 yo
souryo usored-] & sey jeT] WeSTS ajnorted e Jo ware odeupesp reynonsed B soy oBreyosip Sy,
“a8pliq Su] OAOge USE adeUTEIp B Ut “SoTL auenbs ut ‘ware JeUy,

aE&

ak <

wa

iv
AG

ano

Adel

v
va

souasard mnoos SunsIKg
Uppién Jayd wmnupxepy
sueds Jo JoquInN:
Yous Jo spue MORL

addy Tog
adoys jauuey

adAy yelroyun pag

BOULISIP PSq 0} {9018 MOTT

souesad yueqing:

adAa eunngy
wyduay a8pug

Sprig oy) ye Uppias PouURYS MOY-sseq

umaysdn Wausy a3puq auc WPpIM jauUEYyS MOB-oseg

unpis uretd-pooy sanoayyal

sdreyosip poop re04-Q0T
vom send

uoyjeuelaxg

uopeasiqay

ONSLeIEIEUD

S{OURH[[ UE poysolU TOHEMISe snoss paquiaNs-[eIo} payrduis amp ut pasn suoHE}Asqge Poyeroosse Pur SONsts eres ous-s8pyg “T aTqeL,

Davelopment, Verification, and Application of a Simplified Method to Estimate Total-Streambed Scour at Bridge Sites in Winois

4



with the conventional method on many of the bridges,
which is an unacceptable method to estimate scour.

Many of the bridge-site characteristics were
plotted with the total 500-year flood scour that was
estimated with the conventional method. No relation
was found between any single bridge-site characteris-
tic and total-streambed scour. A representative
example illustrating no relation among specific bridge-
site characteristics and the conventionally estimated
total-streambed scour is shown in figure 2.

By trying to represent quasi-hydraulic properties
(because actual hydraulic computations can not be
made) with combinations of various bridge-site char-
acteristics to serve as a surrogate hydraulic property, it
was thought that relations between these surrogate
hydraulic properties and the estimated 500-year total
scour may be obtained. For example, a hydraulic
property such as the flow Reynolds number, which is
the flow velocity times a characteristic depth divided
by the kinematic viscosity, could possibly be repre-
sented by a surrogate measure of velocity, estimated
as the 100-year flood discharge divided by the bridge
length times the low steel to bed distance, and a surro-
gate characteristic depth, such as the low steel to chan-
nel bed distance. Starting with combinations of
characteristics for both multi-span and single-span
bridges that represent the bridge site hydraulic proper-
ties of constriction ratio, flow Reynolds number, and
Froude number, the total scour and these hydraulic
Properties were plotted as a means to envelop the data
points to provide a curve whereby scour could be
estimated. These physically meaningful prediction
variables provided no basis to envelop the data in such
4 Way as to not be overly conservative in the estima-
tion of total-streambed scour. For example, a plot of
the surrogate Reynolds number for multi-span bridge
and total-streambed scour is shown in figure. 3. An
enveloping curve will result in very conservative esti-
mates of total-streambed scour. The plots of the
other “pure” surrogate variable of constriction ratio
and Froude number were very similar in appearance to
figure 3 for both single- and multi-span bridges, and as
such did not provide a useful relation. Therefore, a
trial-and-error scheme was used to add various charac-
teristics and adjust exponents to optimize the envelop-
ing of the data points for each of the six curves. After
seven iterations using the verification data set, two
curves each for single-span and multi-span bridges are
used in the final simplified method (figs. 4-7). Some
of the 213 bridge sites are not plotted in figures 4-7, as

some of the bridge characteristic values required in
the predictor variable were missing from the data
files. As can be seen in the four envelope curve
(figs. 4-7), the physical significance of the predictor
variable has been lost in the trial-and-error process.
The bridge characteristics utilized in the envelope
curves (figs. 4-7) will be defined later and shown on
example bridge site drawings in figures 8 and 9.

Different envelope curves are utilized in the
simplified method depending on the type of bridge
(single- or multi-span). For single-span bridges,
two envelope curves are utilized in the method, and
similarly, for multi-span bridges, two envelope curves
are also utilized, To estimate the total scour for a
single- or muilti-span bridge, the predictor variable for
each envelope curve must first be computed. The
predictor variable varies for each envelope curve and.
consists of an equation combining some of the bridge-
site characteristics from table 1. Once the predictor
variable is known, the total-scour estimate is deter-
mined from the envelope curve. The final total-scour
estimate from the simplified method is determined as
the minimum of the two envelope curves for multi-
span bridges, or the minimum of the two curves for
single-span bridges. For example, if the predictor
variable for multi-span envelope curve 1 in figure 5 is
computed to be | and the predictor variable for multi-
span envelope curve 2 in figure 6 is computed to be
200, then the total-scour estimate from envelope
curve 1 would be 15 ft and the total-scour estimate
from envelope curve 2 would be 9 ft. Therefore, the
final total-scour estimate would be the minimum of
9 ft and 15 ft, or 9 ft.

One curve per type of bridge was intended to
be needed; however, multiple curves were found to be
necessary to make the simplified method as robust
as possible. If only one curve per type of bridge
(single- or multi-span) had been used, the total-scour
estimate at some bridge sites would have been highly
overestimated because of potential anomalies in the
combinations of the bridge characteristics. By
utilizing multiple curves and taking the minimum,
the number of anomalous total-scour estimates was
decreased.

Verification of the Method
The 106 State highway bridges not utilized

in the development and calibration of the simplified
method were used, along with 15 county highway

4 Development, Verification, and Application of a Simplified Method to Estimate Tota-Streambed Scour at Bridge Sites in liinois


JUL Morey ieou yoary xouTeO ON

S@ 08-9561 uou 69r ouou ety OSPOREED OE
a CL 1961 uou Leb ouou 36L “TN ‘sonte: reou ATemIgEN YeoID 3810 OOPOBEEO 6z
st £8-9961 euou 009"6T LOGI 000°LI ‘Ul EAN] AOU OL TPIS OSEOSEEO 14
st 08-9561 1961 ssi 1961 sel “TY “eany zeau Areyngi yserD sud OOEOBEEO Lt
1% 9L-9S61 196 O8F'T 1961 0971 “TT ‘Wapeg way, JeOU FAD YOppBI OLIGLECO 9%
6L e6-S161 euau 007'9S euon 00'S? “TH ‘AND AeTD moje Toapy UsEqeAA STIT OOS6LEEO SZ
“TE ‘AND 4219
cca 08-6961 ou0u 98s auou 90S, ye Aremiquy Joary yseqey, SPW O868LE0 <4
[eA 76-996I suou OO9EE ouou o00‘0E "TIL @IAsTHO] 72 JOART WSeEMA PHT OOGBLELO x4
i TL9SEL OL6T TE6, OL61 96L, ‘TN ‘wmojdayy 18 Areyngin 3901 puccsg OSORLECO a4
lz €6-L96T suou 00L'ET ouou 00v'2T “TT “weysuyjY sway JOATY Yseqem ONT SEIBLECO ir4
es £671 P65 suo 068°L 1961 090°L “TH ‘sumorg 28 y2ory seduog QN08LE£0 0%
“IM "Bu090
€s €6-1b6E su0u 006°8¢ OS6T 00z'Sz Jwou JOATY SBLTEQUI HOH YHON OOO9PEED 61
8 £6-ST6UZT-O16T'806E Su0n a00'es auou ons “TM ‘SERA IG We JOATY SeuquI, OOSSPEEO SE
Te le-Ts61 euou OLo'r T961 O0F'e “Ti AoseD sou yoarD aBuey OOSPEEO al
81 92-6861 ouou UT auOu OFT ‘TI ‘Ainqpooga 2e Areyngen year Appryy SZhPPEEO or
“Tn ‘dnuseip
‘54 08-9861 ouou €L pLél 89 seou AreNgLY Jeary seLIEquI OSTPPELO st
8 CETLETLE-SP6UEPGTOP-6E6T ou0U 00s‘9z uel oOs'Ez “TL PUOIC sea Joary seLrequ OOOPPEEO vai
ee £6-1961 suo 0720's suou oped “TM ‘OBreureD Iwou JoaTY SeIEQUI OOPEPELO €1
“ul ‘stfodeuuy
St 08-9561 suou ca avon 9 sadu AreyNgL] Yaer) wOORA OOGIPELO ral
sl SL-1961 euou OrL suou Eo “yr ‘Sepang sesu Areynqrn 49019 Bq OOLTPEEO WW
Te EGTEET SEL TS-SIET 6e61 oor'Ty GEGTOSELEPET o08'9t “HT ‘opitaueq] seou ear Seid ia QQO6ESED. ol
. “TM “taced
14 9L-9S61 PL6L OsTT yL6l Or0'r seau ATBINUH Jeary UOYTULIEA F104 WON QOSBEEEO 6
4 BS-6E6T €h6l 008'FE POT 000'0 “TTL WIRD Iau JOATY UOTE OOSBECLO 8
[<4 08-6561 euou 878 pucu Tél “TL “weg Tesu Aneynqi YO] WES OOTSECEO L
Be TS-SP6T ouou 006'01 y96T OLL'6 "TU TauOH WOU FIO" WES OOOSELLO 9
6 SL"LEGT $961 one's $96) osre TH ‘sueqiy yw Young suTYs OOSLEEEO s
oF €6-8F61 EEO66TELEL ECB. £6-0661°6L61 O84, “TI ‘euegip) 18 year prekovog OOOLEEED v
£6 16-6561 au0u 096: euou 086'9 “IH ‘Ydasog “1g wou Yloy ES OVSIEECO €
ce T8086 Stou OLE'S 8961 OBL‘ “]U SBUTDIOg 1B Footy sseIToNI GOSIEEEO z
S% 08-9861 suou Ose guou OTE “IL voyxeg Jam Areingin YC Mod Fel OOTIEELO U
paviesqo Piaga pepessxe  saina ‘bay pepesoxe pauno “bed SWEU LOBES sequinn = (en ‘By oes}
saeah JO poped SBM DOLD peybjem sam poyBiem uoyerg dequunu
J0°ON 81804, wou 090 BiBe, wo4j— eousle}o2
(79) OOD (iu) OSD. dew

[soqamu “opy :Aouanbauy “-bauy spuooas 10d yaay 2499 “9/,14 ERE ‘SLND wOY) oBEYOSIp pooy Teah-OOT
pepeeoxe 616M Senjea UBYM S1BOK PEyE|OOSSS YUM S!OUTII] U} SUOREIS BujSe6-urans fening [201Bojoes “S*7 18 seBreyosip pooy seed-90) pur

“01D ‘14961 ‘spAnD Woy) aBreyosip swek-gs OSD]
-09 Jo epnyubey

‘eael

Development, Verification, and Application of a Simplified Method to Estimate Total-Straambed Scour at Bridge Sites in Itlinois

20


DEVELOPMENT, VERIFICATION, AND
APPLICATION OF A SIMPLIFIED METHOD
TO ESTIMATE TOTAL-STREAMBED SCOUR
AT BRIDGE SITES IN ILLINOIS

U.S. GEOLOGICAL SURVEY
Water-Resources Investigations Report 95-4298

Prepared in cooperation with the
ILLINOIS DEPARTMENT OF TRANSPORTATION, DIVISION OF HIGHWAYS



5. After all categories have been filled in, click on
the Calculate Scour button. The estimate of total
scour will be near the bottom right of the window.

6. To save the input data and results to a computer
file, click the Save Data button. An example
output from ILSCOUR for the single-span bridge
example previously presented is shown in
figure 22.

If the Windows software package is not utilized,
the following are instructions for use in the Disk Oper-
ating System (DOS) mode.

1. Type ILSCOUR at the DOS prompt. This will
invoke the ILSCOUR program.

2. The 100-year flood discharge is not computed
in the DOS version of ILSCOUR; therefore, the
100-year flood discharge must be computed by
another means before using the program.

3. Ateach prompt, enter the requested input to
compute the total-scour estimate.

SUMMARY AND CONCLUSIONS

A simplified scour estimation method was
developed by the U.S. Geological

Survey (USGS), in cooperation with the Wlinois
Department of Transportation, for application to local
agency bridges in Illinois. Data from 213 State bigh-
way bridges, previously analyzed for total-scour
estimates with conventional methods, were utilized to
empirically develop 500-year flood total-streambed
envelope curves. The State highway bridges were
selected on the basis of geographic distribution and
similarity to local agency bridges. A separate verifi-
cation data set of 106 State highway and 15 county
highway bridges was used to verify the simplified
method. The method consists of determining predic-
tor variables (combinations of bridge-site characteris-
tics) used to estimate the total scour from each
applicable envelope curve for a bridge site. Two
envelope curves are applicable for single-span bridges
and two curves are applicable for multi-span bridges.
‘The minimum of the total-scour estimates from the
applicable envelope curves provides an estimate of the
500-year fiood total scour. Verification proved suc-
cessful with the simplified scour-estimation method,
underestimating the conventional scour-estimation
method on only five bridges in the verification data
set.

ILSCOUR OUTPUT

Stream: Flatville

Single Span Structure

Drainage Area

100-Year Discharge 2082.933 cfs

Floodplain Width 37 feet
Channel Width at Bridge 23 feet
Channel Width Upstream 26 feet
Bridge Length 67 feet
Low Steel to Bed Distance 11.05 feet
Bed Material sand/silt
Cutbank Presence None

Abutment Type

sl 5.695 feet
82 9.772 feet

Estimate of Total Scour 5.695 feet

Scour Project - Illinois District, U.S. Geological Survey, WRD

Drainage Ditch near Flatville, Illinois
Bridge Number and Location: Structure 4357, County Road 20505

10.75 square miles

Spill Through

Figure 22. Sample output fromm the computer program ILSCOUR for estimating tatal-streambed scour at bridge sites in

Ilinois.

Summary and Conclusions 43


odo'ol

00'L

1X

oL

2a6't-(ixdur ga06's = 4

yee} ul ‘yy6ue] eBpyg =
yee) uy ‘oBpyg out
ye YIPIA jouUuBY Moy-eseg =
709} Ut ‘Weansdn YyiBue] eBpuq
QUO UIPIM JeUUBYD MOY-BsEg =
499) Uy “ULpIM UleId-pooly eANoBya =
pucres Jed yea)

POPO'O-(LX)EZO'O+, (LX) gp. OL # = A

Ma
amo

Mo
Md

oiqna ul ‘eByeyosip pool 4eek-00} = 0

ma
go (BMO-NMO+09) * gg Medley. 9®

u) 011s eBpyq 40) poyyeus PeuORUSAUOD ey! UIE PSyEUINISS JNOES [e10} Jo) | @xino adojenue URds-o[BUIS “y eUNB]y

41334 NI ‘HNODS GALVWILSS 8l-D35H

7

Simplified Method to Estimate Total-Streambed Scour



ODE

“g]0u!

YASWNN SCIONASH ALYDOuNNS

08

oRe ose Ope oze leer 08 OSL Or Ozh all
T T T v T T T T t T

quewinge
Oo} UeUNGe Wo Wp ebpug = Ag
¥9) Ul ‘Wdep peg Oj e035 MOT = GIST
Puooes Jed
386} O1gN9 ur! ‘eGeYosip sBek-OO) = H

M@ MG « €ls7

Oo “asix 5

= JeqUNU spjolKey ereboung

se

Of

SE

Or

og

| U seBpuiq Ueds-Inu 70) pomneu |EUORUEAUD eu) YUIM PeleUIASE ANODE jzI0) PUB JequNU sploUAey eyEBoUNg “E eunBly

4354 Ni ‘UNOS GALVWLLSA 81-035H

Development, Verification, and Application of a Simplified Method to Estimate Total-Streambed Scour at Bridge Sites in Winois



to be valid. In addition, the ratio of base-fiow chan-
nel width at the bridge to flood-plain width was 0.13,
which also meets a pre-established criterion that the
ratio must be greater than 0.03.

The length from abutment to abutment for the
bridge over the Embarrass River was 125 ft. The
bridge contained three spans as two piers are present.
Both piers have square noses, which are coded on the
field sheet as a type 1 pier (see fig. 8D). The angie of
attack of the fiow on the bridge piers was determined
to be zero degrees as the flow lines for a flood appear
to be parallel to the length of the bridge piers. The
width of each pier was 2.25 ft. If the piers had differ-
ent widths, the larger pier would have been entered on
the field data sheet. The distance from the low steel
of the bridge to a mean streambed was measured with
asteel tape at 11.1 ft. The location of the representa-
tive streambed is subjective, but generally should
equal the average streambed elevation for the main
channel.

Examining the streambanks both upstream and
downstream in the vicinity of the bridge, small local-
ized cutbanks were noted. A “2” was coded onto
the field sheet in the Cutbank Presence category to
indicate that slight cutbanks were present at the site.
No scour was noticeable at either the piers or the
abutments. Therefore, a “1” was coded in the
Existing Scour Near Piers/Abutments category.

The bed material type was determined by collecting
and inspecting a sample of the streambed. By quali-
tative inspection, the material was determined to be
of a silt/clay composition and a “4” value was entered
into the Bed Material category as specified in the
instructions.

Once all the necessary data were collected, an
estimate of total scour was made utilizing the simpli-
fied method. The 100-year flood discharge was not
known; therefore, to determine this value, methods
outlined in Curtis (1987) were used to compute a value
of 1,770 fC/s. Examining the simplified-method
envelope curves 1 and 2 for multi-span bridges in
figures 5 and 6, the predictor variable for each enve-
lope curve was calculated and a corresponding total-
scour estimate was determined from both of these
curves at 27.8 ft and 24.8 ft, respectively. The mini-
mum of these two values (24.8 ft) is the final estimate
of the total scour at this bridge site.

Computer Program ILSCOUR

The computer program ILSCOUR.EXE can be
applied to compute 100-year flood discharge and for
estimating the total-streambed scour (combination of
contraction and pier scour only) resulting from the
500-year flood at the bridge site. If the Windows”
software package is utilized, the first data entry page
of the ILSCOUR.EXE program is shown in figure 18.
Following are instructions to use the Windows version
of ILSCOUR.EXE.

1. After invoking the program in Windows, using
the right mouse button, click on either the Single-
Span Bridge or Multi-Span Bridge button
(fig. 18). If Multi-Span Bridge is selected, the
user will see the screen shown in figure 19.

2. Using the mouse, position the cursor next to each
highlighted category, click, and type in the neces-
sary data.

3, If the 100-year discharge is known, then type in
the value, otherwise click on Calculate Discharge
and the screen shown in figure 20 will appear.
From this screen (fig. 20) click on either Rural
Method (method from Curtis (1987) for ungaged
basins) or Urban Method (fig. 21) (methods from
Allen and Bejcek (1979) for ungaged basins in
northeastern Illinois). NOTE/WARNING:

The ILSCOUR.EXE program only computes the
100-year discharge based on the Site on Ungaged
Stream method in Curtis (1987). If the site is at
or near a gage location, consult Curtis (1987) for
appropriate methodology. In addition, applica-
tion of methods outlined in Allen and Bejcek
(1979) sometimes result in a smaller 100-year
discharge estimate than methods from Curtis
(1987). The Rainfall Intensity and Regional
Factor categories can be presented in a map if the
user desires by clicking on the Show Regions or
Show Intensities button.

4. Single-span bridges, click on the down arrow for
choices of Abutment Type, Cutbank Presence, and
Bed Material categories.

Muiti-span bridges, click on the down arrow for
choices of Cuthank Presence, Pier Type, Existing
Scour Presence, and Bed Material categories.

2Use of trade names in this report is for identification
purposes only and does not constitute endorsement by the
USS. Geological Survey.

Application of the Method 3


6t O86T'8L-1961 ono sts auou wep “Hi ‘xo eau Z ‘ON Ansingin yeary xoq OOBTSSSO Sve
€€ £6- 1961 euou Ore'z £861 o10'z, “TIE 'SITAYLOA, Teau yas Ausqyoei OOLTSSSO 444
SI SL" 1961 uou oop euow WE HD etaereg Jeau Aremqin une aye] aSoTsssO ee
il 6L-6961'L9-S9G6T+E9-T96T suou rs su0u S8L [HL ‘aT[Aouey reau year) AUsqyor[ OZSTSSSO 444
él 6L-1961 uo S06 arou 98 “TM BzOIMY Je FOAUD WeIpyy ESTSSSO We
al 6L-1961 auou 19F BL61 SOP “HL “Bion YON Jeau Yoary WePUT OZSTSSSO Ore
ee £61961 auou 00% suou Obr'z “IT1 'S91YQ “IS sBOU Year VOSIAT OOZISSSO 6EZ
61 GL-Z96TLS61 L961 OL L961 6iE TIL ‘S9H8YD 3S TAU ysaxQ UOLON OSOISSSO Lix4
61 OL-T96TLE6T L861 OFL LOGTSLS6T 685 “WI ‘oudepy TeoU Yoary UCLON OSOISSsO L&t
st 6L°7961 uu 8E6 euow Lig TIT “sat, Ad]TeA 72 HOD Josmar_ OCOTSssO OES
& 6-761 auou OE0't sucn v6 “WI ‘tHBiq w y2exD Tedog GOsosesO —-SEZ
61 6L-1961 L961 Ors L961 tLe ‘nopreg mau Areingin yor) eidod OLvOSSSO ee
al LL-1961 suou L6S auou Les “TE ‘eqToueG Tweau ysex JePdog osPosssa eet
“I ‘ounered
cas LL-196T 4961 gst L961 €2e Jean Yaarg sedog yourrg ise] OEPOSSSO cara
ét 08-BLOHSL-SO6IE9-T961 euow OL Suou eso “TM ‘UHBTa Te Y90ID J9}AL, ODEOSSSO 1tz
BL £@-9T61 ouou OEPL ouou 0189 "TIL ‘uinbuodyy 3 19ATY xO 0OOISSSO Et
ve 6L°9961 ouou RL euoU cd UT ‘Areg seau Arenngys Joara XO O066PSS0 67
07 £6-0661'9L-Z96 10961 0961 Lob 0961 cep “III ‘9A0ID JOATY NOY TWO Asad IL OS86PSSO 87
91 9L-CO6T0961 ouou 10s guow oly “TUL ‘2321 PURIST Te Yeas WOH, QOLGPSSO Le
4 26 6r6T uo TLE 9861 Lee “TH ‘ATUSPOW. Jesu YoaTD BUOO OOOGFSSO 9
8% £6-996T suo ope'e suon oLo's “TY ‘eaorry Suds eau yeorD yusieddin O87sPSsO Ste
4 €6-P06T‘0061'86"F68 12681 suon Q00's01 aou Q0ss6 “TIE ‘se]]easTe PA] ¥2 Joaky STOUR], OOSEPSSO L444
$s £6-0F6T suot oorse £861 GET “WL Ard Rog Feo Jeary uozeW] GOOTPSSO 1544
44 08-6S61 ouoU 09% euou Ove. “TIT seupsen Jeon Areinqun 19Ary UOZEAL OSLIPSSO Tee
€s €6°1¥61 arou OOFZT SS6lBr6t 08'0T “{I1 ‘poomaroyg Te zany eBed MC OOSOPSSO Tee
0% 08-1961 Suou OTL euou 609 “TL BIS] eau Yoory sual OpZOPSSO 02
di EL-1961 SuoU Sr6 auou sss [1 ‘Moura 18 yeep ydosoe IS O6TOFSSO 61Z
“TI ‘Saag SISUMOC
4 £6-0661'9L-E961 19615865 quou ole suon oss'l eau JAtY a8uq NC ee 38Bq  OSTOPSSO BIZ
TH BATTS VAD
61 08-€96T:1961 ZL6T 198 GL6I SSL We saary oe nC Yourlg sey OSTOPSSO LIZ
“TH ‘erepsupwooTg
él 62-1961 suou 19% auou Le Jeou I9ATY Oded NG Yous eT OFIOPSSO o1z
paniesqo. puosel pepesesxe = gaina “boyy, pepeesxe enna ‘boy, SWEU UONRIS sequinn = (} “6y es)
sieok jO poled SBM 0010 peyyBjam SUM payyBiem UOTaIS dequinu
40ON A wiosy- DSO sIEe, woay- saueiejel
(sigH) 0010. (sf) 0S dew

penuyuog—pepeeoxe

GJSM SONJEA UAYM SueeA POFZOOSSE LIIM $/O1 4 suopEys BuiBeb-wueess Aerung solBojoey “S'11 18 sei BYOSIP POoy 4BeA-QO} PUR -OS Jo epnyubey ‘2 SIGeL



Application of the simplified scour-estimation
method requires less field and office time than with the
conventional scour-estimation method. The bridge-
site characteristics needed to apply the method can
be obtained from an office review of bridge plans,
USGS 7.5-minute topographical maps, and a brief site
inspection. The simplified method has been demon-
strated to be conservative in estimation of the 500-year
flood total scour when compared to conventional esti-
mates of total scour. ‘The simplified method,
conservative in estimating the 500-year flood total-
streambed scour, can be utilized. in estimating total
scour for a large number of bridges without perform-
ing the more complex conventional hydraulic and
scour computations. This facilitates screening of
bridge sites so that the more detailed conventional
analysis is only applied to more complex and problem
sites. A computer program (ILSCOUR) was written
to automate the application of the simplified method.

REFERENCES

Allen, Jr, H-E., and Bejcek, R.M., 1979, Effects of urban-
ization on the magnitude and frequency of floods in
Northeastern Hlinois: U.S. Geological Survey Water-
Resources Investigations Report 79-36, 48 p.

Becker, L.D., 1994, Investigation of bridge scour at selected
sites on Missouri streams: U.S. Geological Survey
Water-Resources Investigations Report 94-4200, 40 p.

Code of Federal Regulations, 1992, 23 CFS 650
Subpart C, National Bridge Inspection Standards,

U.S. Government Printing Office, Washington, D.C.

Curtis, G.W., 1987, Technique for estimating flood-peak
discharges and frequencies on rural streams in
Illinois: U.S. Geological Survey Water-Resources
Investigations Report 87-4207, 79 p.

Matthai, H.F., 1968, Measurement of peak discharge at
width contractions by indirect methods: U.S. Geolog-
ical Survey Techniques of Water-Resources Investiga-
tions book 3, chap. A4, 44 p.

Mueiler, D.S., Miller, R.L., and Wilson, J.T., 1994,
Historical and potential scour around bridge piers and
abutments of selected stream crossings in Indiana:
U.S. Geological Survey Water-Resources Investiga-
tions Report 93-4066, 109 p.

Richardson, E.V., Harrison, L.J., Richardson, J.R., and
Davis, S.R., 1993, Evaluating scour at bridges:
Federal Highway Administration Hydraulic
Engineering Circular No. 18, 132 p.

a4 Bevelopment, Verification, and Application of a Simplified Method to Estimate Total-Streambed Scour at Bridge Sites in Illinois

‘AUS. GOVERNMENT PRINTING OFFICE: 1996 - 747-151


6 671961 oun LT suou Sve “MM ‘aTTAuoreyy 1 yoorD AUT QTIOPSSO SIZ
"TT “Apftauarie yy,

4 £6-6961 £861 asst 2861 OLET wou JaaTy a8eg nq youerg isa S600KSSO FIZ

él 6L-1961 z61 aa 7261 TE TI ‘wowaqay 8 YOOIg dg QEOOPSSO EIT

8 €6-9861'08-1961 avo 289 $961 919 “TT ‘Odeo W941 BAIN Ss QIGOPSSO ZZ
“TIE ‘OB Bo1yD 1S2M

0% GL-I96T'SS6T enou O9L'T ZL61 O19 Je reany oBeq NC] YoueIT SAM OEOPSSO ue

6r 61-1961 ZL61 94 zL61 a9 “TIT ‘umwang joreg 8 Y9e1D UTY OsssEsso 1
“TH ‘odwoeyS 184

ee £6-1961 auou Oor'T ouou O10'T Jeau Joany adeg NG YURI Se, OOSEESSO 607
“TH ‘oud,

4 6L-196T'SSEL auou O8L'T ss6l OFs'T Jwau Joary aed UC yOUBI SAM O6EESSO «807

“TIL “aqAoue UG

61 6£-1961 ‘auou bbb euou €S8. Je Jeary a8ed NC WURIG SBA OLBEESSO L0
(45 €6-SPETZP61 976 T-ZO6T 1861-ZO6E o0T‘9T TR61°LS61°Z06T 00671 “I “Tour Fe Yer MOY OOGGESSO 90%
aT LL-T96T-SS6T SSéT raul SS6 oor “TH Hed PUETC Kou YoaND Buds OpPsEsso $07
81 ZESI6L uou O0v'Ez suou o0r'7z TIE ‘Tatyor 18 JOATYE seureTd S89 GOORESSO. vOe
€b E6rISET gsét O6L'T LS6U-SS61 ocet “Ill uous] yeau ony Bue] OOSLESSO £07
0c 6L-196LSS6T SS61. O€g'T ssér OFT “Id Wed Soped W F293 TA OC9IESSO 0%
él LL-196T suou PSE 996T LTe “TL Hzed Sofed wou Yea TNA OZ99ESSO 107
st 9L-T961 auow og9o'T 9L6T Otr'L “TH “TH0,4 1 (seq) yEID AuoIs OASOESSO o0z
6I O8-Z96T suon 61S suor esp “UT OMe] YeQ Teo YoU eUTATAI GOS9ESSO. 66T
61 6L-196T auou Os suon PLP “TH S1US19H soyed We YoarD ofeaen’ OTSOESCO 861
cA EG-LSGLSS-1S61 auon Ore Se SS61 Ol6T “Hl ‘ed Sofed Jeau yaary Avjay], GOSESSO 261
él 6L-196T su0u osz'T suou Orr “TIL I8e104 FBO Tou YearD Ao[UL_, OVPOESSO 961
4 €6-1S61 uou zo €L61 BLS “IH {8220.4 YEO We Jeary UVNPo[pl OpPEIESsO S6T
9 6L-PS61 emu cats LS6L:SS61 09 TH eq AB[ULL Iau YoarD weMpoyprn SEEIESSO Pol
af SE-LT6T auou ose's eu0u 098'F ‘TIT *Aoarey 3e Jeary lume eT SzESESsO £61
Wh wey
Br SL-I96T!LS6I°SS61 ouou Tas Suou os Jeau JeutD sBeurwiq uoluy LIN OTE9ESSO TéL
ip C6-LP6I ecou O8t's guou Ozer “TH ‘PUR ION Wns 3 JoATY SUMNTED BRIT OGZ9ESSO T6L
ie €6-Lr61 ouou oge's ouou oss'r ‘IIT ‘MowoYy Te Yay wos, 6Lz79ESs0 06
ve 6L-8F61 Suou 668 suou L18 “HL Suysue7] wou Y291Q MON OLZIESSO 681
oF £6-8P61 auou LIg ‘auoU ely TN ‘Bursuey reau yoni BusueT SOzOESSO 88
Sb E6-LS61'SS-BPST ouou 006'2 suou aa “II Toousssopy ye Year) PlyouM SSz79EssO 281
61 6L-1964 euou IIL. euou 009 “TH ‘sorersg UOoUr] Jesu YsorD ppegyreung RETIESSO 98T
paasssqo pangas pepesoxe sand “bey popaaoxe eaxino ‘boug BUWUEU USES sequinn (21. “By 908)
sueek JO Pojed gM 0OLD peryBjan sem peyyBjom uopeas aequinu
40 'ON BBO, wor 090 BIB, wodj- eouss8j01
ig) ooo (si) oso. dew

: panuyjueg—pepesoxe

26 . Development, Verification, and Application of a Simplified Method to Estimate Total-Streambed Scour at Bridge Sites in IHinois


NS

nN

EXPLANATION
VALIDATION BRIDGE

CALIBRATION BRIDGE

“

60 MILES

2
=

© 20 40 60 KILOMETERS

ar

2
©
=
s
$
2
5
3
3
3 58
= Be
& oe
Bay
Baek
ses.
S988
2iar
O5rs
BOTS
2338
ere
go $e
aod
al2H

Location of bridges used in calibration and verification of the simplified method to estimate total-

Figure 1.

streambed scour in Illinois.

3

Simplitied Method to Estimate Total-Streambed Scour



Application of the Method

For each bridge to be evaluated with the simpli-
fied method, several bridge-site characteristics must
first be determined. The field/office data sheets that
can be used to compile the bridge-site characteristic
data needed to successfully apply the simplified
method are shown in figures 11 and 12 for single- and
multi-span bridges, respectively. After the necessary
bridge-site characteristic data have been compiled, the
user can manually determine the estimates from the
applicable total-streambed-scour envelope curves and
compute the minimum value. The computer program
ILSCOUR (see Appendix 2), specifically written to
estimate the total-streambed scour with the simplified
method, also can be used to determine the estimates.

For both single- and multi-span bridges, the
100-year flood discharge is required for the simplified
method. This may have been previously determined
during desigh of the bridge or may have to be com-
puted from methods outlined either in Curtis (1987)
for rurat basins or Alien and Bejcek (1979)! for
urbanized basins in northeastern Illinois. Options
to compute the 100-year discharge by either of these
two methods are contained in the ILSCOUR program.

As previously discussed, the simplified method,
by design, is conservative in estimating the total-
streambed scour at a bridge site.. Each bridge would
be analyzed with the simplified method and bridges
evaluated as stable for the total-scour estimate with
the simplified method would need no further analysis,
whereas bridges that were determined to be unstable
or borderline, could be reanalyzed on the basis of
the conventional method outlined in HEC-18.
Furthermore, the past occurrence of scour at the
bridge site during major floods should also be taken
into consideration. The years that greater than 50-
and greater than 100-year floods have occurred for
the period of record at USGS stream-gaging stations
are listed in table 2 for the gages shown in figure 13
to assist in documenting when significant floods have
occurred on various streams in Illinois.

An example of both a single- and multi-span
bridge is presented to demonstrate the application of

‘The method outlined by Allen and Bejcek (1979) is rarely
used in Iltinois as it has often yielded smaller 100-year flood
discharges for urban basins when compared with the method
outlined in Curtis (1987). If the Allen and Bejeck (1979) method
is used, it is recommended that the larger of the two 100-year
discharge estimates from these two methads be used.

the simplified method, Total time to collect office
and field data and compute the total-streambed scour
estimate was approximately one-half day per bridge
site.

Single-Span Bridges

Knowledge of all the bridge-site characteristics
on the field data sheet shown in figure 10 is required in
the simplified method for single-span bridges. Once
the bridge-site characteristics are determined and
listed on the field data sheet, the two envelope curves
for single-span bridges should be used to determine
the estimated total scour at the bridge site. The
collection of the necessary data from single-span
bridges and determination of the total-scour estimate
are demonstrated in the following example.

A single-span bridge over Fiatville Drainage
Ditch near Flatville, Dlinois (fig. 14) was evaluated.
Site plans, provided by the Champaign County
Engineer’s Office, and a topographic map of the
bridge site and associated watershed were reviewed
in the office before visiting the site. For many bridge
sites, the construction plans contain such information
as the abutment type, drainage area, 100-year flood
discharge, bed-material type, or bridge length from
abutment to abutment. However, for this bridge site,
only abutment type and bridge length were readily
determinable. From the topographic map, the drain-
age area was determined to be 10.8 mi’, In addition,
the elevations and thalweg distance required to com-
pute the 100-year flood discharge outlined in Curtis
(1987) were also determined from the topographic
map. The Rainfall Intersection and Geographic
Region values are determined from the graphs in
Curtis (1987).

At the bridge site, most of the other bridge-site
characteristics were determined and listed on the field
data sheet for single-span bridges (fig: 15). For this
bridge site, flood-plain width for the 100-year flood
was taken as the distance between the top of the banks
(37 £0. This is because for flows above the banks,
the water would go over the road, as this area is very
fiat. For the simplified method, the effective flood-
plain width is that width which contains water of some
velocity greater than zero (not ponded) that goes
through the bridge. For cases with road overflow,
only the part of the flood plain containing water flow-
ing at some velocity and proceeding through the
bridge opening is considered part of the effective

Application of the Method 17


88°18" ere 48°
1

Michigan

42° 16

4 45 4

9 5 10 MILES
0 5 10 KILOMETERS
EXPLANATION
STREAM-GAGING STATION AND

28 MAP REFERENCE NUMBER -
(See table 2)

Figure 18. Continued.

34 Development, Verification, and Application of a Simplified Mathad to Estimate Total-Streambed Scour at Bridge Sites in Hlineis


Figure 14, County Road 2050 East single-span bridge over Flatville Drainage Ditch near
Flatville, iit.

flood-plain width. For very wide flood plains, an
effective flood-plain width that is some factor times
the length is recommended (fig. 8), especially when
levees or other distinguishing laterally controlling
features (for example, a valley wall) are absent. The
magnitude of the factor can vary as based on engineer-
ing judgement.

The base-flow channel width was measured
from the left descending bank water surface to the
right descending bank water surface with an engineer’s
steel tape. The base-flow channel width was 23 ft
at the bridge and 26 ft one bridge length upstream.
The abutment type, determined from bridge plans
and verified from the site visit, was a spill through.

A “1” was coded on the field sheet as specified in the
instructions. Diagrams of spill through and other
types of bridge abutments adapted from Matthai
(1968) are shown in figure 9, No cutbanks were
noted after examining the streambanks both upstream
and downstream in the vicinity of the bridge, and “1”
was entered onto the field sheet in the Cutbank Pres-
ence category. The distance from the low steel of
the bridge to the average streambed of the main chan-
nel was measured at 11 ft with a steel tape. The
bed-material type was determined by collecting and
inspecting a sample of the streambed. By qualitative

inspection, the material was determined to be of a
sand/silt composition and a “4.5” value was entered
into the Bed Material category as specified in the
instructions.

Once all necessary data were collected, an esti-
mate of total scour was made utilizing the simplified
method. The 100-year flood discharge was not ~
known; therefore, methods outlined in Curtis (1987)
were applied, resulting in a 100-year flood discharge
estimate of 2,080 f(?/s. To estimate the total scour,
the predictor variable for both single-span envelope
curves (figs. 3 and 4) was calculated and a correspond-
ing total-scour estimate was determined from each of
the two curves as 5.7 ft, and 9.8 ft, respectively. The
minimum of these two values was used as the final
estimate of the total scour at this bridge site. Asa
final check, all the bridge characteristics for the site
were in the acceptable range of values used to develop
the simplified method (see “Limitations of the
Method” section). In addition, the ratio of base-flow
channel width at the bridge to base-flow channel width
one bridge length upstream was 0.88, which is greater
than the 0.5 limiting value described in the “Limita-
tions of the Method” section. The ratio of base-flow
channel width at the bridge to the flood-plain width

Application of the Method a5


23

Appilcation of the Method

oz £6-0661°9L-7961 ‘0961 suou OST ouou OzF'T TH 22D TH PIO ® ¥9AD THA OS6L7SS0 is43
LI 92-0961 su0u BLS anou 6s “TIL S180 ATO¥PTH Te S279 MAL UVON 06LZSS0 per
dt 92-0961 O96T 62E 0961 282: “TIL ‘Tauro soBpoy, 12 FAI TIAL OLBLZSSO x4
si 9L-2961 auou ose ouou Ops'z TT ‘uomspeay ye JaaTy Saure[d Se OFBLZSSO ras
€€ €6-8961°99-0961 ouou oco'e ‘ST0u ors'e “I Tassny vw Jeary soure[g Seq, 008LZSS0. Ter
6L €6-SI6T iset o0r's9 T66TE861:ZS61 o0L'09 “NL uorBuTUN YA Te0U ToATY coyeMUEY OOSLZSSO «Ot
rag 7L-OS61 S61 Leb isel 69€ TM WoyAUEIy War yaar) Tel OSOLZSSO «6.
9% $L-0S61 0161 O0z'T oL6L 896 “TL ped Jeisng seu YoauDy AUal, OOSVZssO «BIT
“HIE ‘sreudoqinog
.34 08-9561 suou £0. Suou Bez qeou Areingyn Jeary soxeyUEH OST9TSSO dit
Te CO-VEETETOT £161 ores €16t 00167 “TH ‘esueqoy) mou JaAny slonboH —9ON9ZSS0 OIL
a 6-661 Saou 0099 1961 OOEIe “TO "PIOFTIA 38 YAN TeBag OsSzssO Sit
it TL-9S61 £561 O6L'1 LS61 O9¢'T "THI ‘Bopisyg Jesu MopoH Wingisey OSOSZSSO La
6b £6-SP61 BS6I O96 Ss6r 069'8 ‘UL ‘sionboyy ye Jeary sionbory goOsTssO €11
6L €6-ST61 6161 OOE‘ET 6L6T 00r'ZT “TI ‘SouSUTO YA] 38 JoANY sayeyWEyY OOSOZSSO ran
ee LL-SP6I 9L6l ore OL6T Oste “TL TOUNTTT 28 Yani] UoIeFBUES ODOZSSO He
st 08-9561 euow O94'T suou Osr'T It ‘PuaID swou yoary Bund yes OOZETSSO On
te 98-0F6T auou O0z'St Ov6L ooe'ze “TH ‘ogant7e yaar Avg OOOEISSO Ol
oS €6-0F61 ouou OOTLT uou ool'si “TH ‘Praystitd 38 42019 AB NSZTSSO 801
st 08-9561 ouou O0S‘T 996T OLe'T “TH ‘Aumeg seou Aremqun yeeI9 40ST 0ZTZOSSO LOT
ie 98-0F61 ouou 00207 suou OoT'sT “I ‘ooupopury ye ye0r9 AorpeH OyOTOSSO 901
Le £6°C66T'06-9S61 suou OorZL auou 00801 “Ul ‘Aueg zwen yoar5 Ao[PEH OZOZOSEO Sor
oI 9L-1961 auou 6i8 2961 €€b ‘TH Toung teou AreEyngen yae1D uoUN GOSTOSCO Or
Te 9L-9S61 auou 020° suou $76 “WL ‘Aound swou Areingin year weUtoH] 00696%S0 OL
os £6-Pr6T suou 00'0E S861 00s‘9z “TH ‘SUR Isasepy Jeol yay wag =OOSSEPSO zor
St O8-9S61 suou OT suou o9r'T “TH “eSprmexarg mo yoexD OPT OOTS6PSA tor
st 08-9961 ouou 007. Qs6T SLL “HE SUtAosoy seou Areingyy Fax] UOSTTI OSL69VSO O01
ee 78-0F61 z861 000°0T TAGTELET oso's “TH OpfAs3ig ye yaaxD Uosspuay YING GOS69SO 66
6S t6-SE6I £661°Z861. 00z'%z S661:7861 o0s's1 “TH “2yKenbo wot yoasD uosIopuay 00069PS0 86
we €6-O86T'8L-1P61 £661 000°ET €661'2861 o08‘0T TH ROA ST 18 HoAID Jepsy OOSROPSO 46
aif TS-1e61 auou Ore't suau 06s'% “TU ‘Woreas Jean yaar uosTapuay THON O0089rSC 96
a T8-1r6l 7861 O0€'Z1 ZBL odo‘o! “TW HOA any] weau YaasD Vostepusy] OOSLOPSO $6
ss £6-1661:98-SE6T €L6t OST'8 £661 -C86UELEE Ore ‘TH ‘Bingsyney seen ysery edog 00L9PS0 6
6S £6-SE6I €L6T 000°ET ELOT 009'TT “TI ‘voIsog Man JHaU JOARY SpreMpA OOS99PSO 6
&s £6-TP6L IS61 OBL. 1S6i O6t'L “IE UOC Tea JOARY Sprempy 0ON99PSO o9
St 08-961 suow €ze su0n 14 “HI ‘Wey Jeou ysarQ pueg OSOs>PSO 16
PeAsasqo: pucges Pepesoxe = evn “bea pepesoxe nuns ‘bely aweu Woes jequinn = (g} 643 468)
e1B0A JO payed SBM DDO peqybem Sey polyBrem uOoBeIS Jequind:
19'ON S180, wo- agp ste, woy- e0ue8}e1
(s/4) GoLo. (s/) 090 dew
penujuog—pepesaxe

JOM SEN|eA USM BIBOA PEyBiOOSse YIM SlOUIN] Ul SUOHEYS BUIbe6-weeys Aenung jealGojoeg “g‘f ye sefeyosip pooy seef-O0} pue -0g jo epnyuBey) *Z ejqel,


CONTENTS

Abstract
Introduction.......+--.6s sere reer ee
Simplified Method to Estimate Total-Streambed Scour .
Development of the Method. .
Verification of the Method .
Limitations of the Method .
Application of the Method.
Single-Span Bridges
Multi-Span Bridges . .
Computer Program ILSCOUR .
Summary and Conclusions .
References

APPENDIXES = In Pocket

1. Computer File of Bridge Characteristics and Scour Analysis For 303 State Highway Bridges—(DATA.TXT)
2. Computer Program to Compute Total Streambed Scour by the Simplified Method—(ILSCOUR-EXE)

FIGURES

1. Map showing Jocation of bridges used in calibration and verification of the simplified method to estimate
total-streambed scour in Illinois.
2-7. Graphs showing:
2. Channel slope near the bridge and estimated scour determined with conventional methods for a
500-year flood for bridge sites in Illinois +e
3. Surrogate Reynolds number and total scour estimated with the conventional method for mul
bridges in Illinois...
4. Single-span envelope curve 1 for total scour estimated with the conventional method for bridge sites
FOr 11 Fer tes
5. Single-span envelope curve 2 for total scour estimated with the conventional method for bridge sites
jn Wnts oc ce ee eet ee cece etree seen ener ere r enter seer e eres seer eee ee
6. Multi-span envelope curve 1 for total scour estimated with the conventional method for bridge sites
in Minois ... 0.0.02 eee eee eee nee beeen ene eterna ers sea rages eee sess eet
7. Muilti-span envelope curve 2 for total scour estimated with the conventional method for bridge sites
in Minois
8-9. Diagram showing:
8. Plan view and detail of bridge site and characteristics for a hypothetical bridge site. . . .
9, Abutment types (adapted from Matthai, 1968) used in the simplified method.........
10. Graph showing estimated total-streambed scour determined with the conventional method and estimat
total-streambed scour determined with the simplified method for bridge sites in Illinois
ll. Field and office data-collection sheet for single-span bridge sites in Hlisois .
12. Field and office data-collection sheet for multi-span bridge sites in Tllinois . .
13. Map showing U.S. Geological Survey stream-gaging stations in Illinois corresponding to flood frequency/
exceedance data
14. Photograph showing County Road 2050 East single-span bridge over Flatville Drainage Ditch near
Flatville, I. 0.0... e cece eee erence ee eee ener ee eeestesersenebererressssrrsstnss sees ee
15. Sample of a completed single-span field and office data-collection sheet for County Road 2050 East bridge
over Flatville Drainage Ditch near Flatville, 111
16. Photograph showing County Road 300 North multi-span bridge over the Embarras River near Pesotum, Ill.
17. Sample of a completed multi-span field and office data-collection sheet for County Road 300 North bridge
over the Embarras River near Pesotum, Ill

Contents

9

. £0

il
. 13

-. 16
. 18

19


“(6261) ya0I8g pUe LAITY Ul paUINO spoujoW Bulsn sulseq ueqin peBebun Jo, eBseyosip Jeaé-00} Bupepnajeo soy useuos jndui 4X3 WNOOST1

“be aunBiy

Ino spojew Suisn sujseq yeins peBeBun so) eBreyosip seek-00 |, Bupe(nojeo Joy Uses0s yndul 3x3"WNOOSTI

“oz oanBig

abieyasiq aeynaye5

Development, Verification, and Application of a Simplified Method to Estimate Total-Streambed Scour at Bridge Sites In Ilfinois

42


‘seBpyq ueds-e/Buls 10) usados Indul 3X HNOOST “eb eanBis

5319903)

3 | auoy E
ue e 5 Dey Santis oe 3 ats 5 eres 8 nee
: ybnoy) id

| - a

reine
a
ie
ation, and Application of a Simplified Method to Estimate Total-Streambed Scour at Bridge Sites in Illinois

40 Development, Ve



“StOUl)} Ul SoYs @BPLG Jo) PoyJeU [eUo|UeAUOD AY) YIM PeyEUUISe JNODS [210] 10) Z eaino edojeaua UEds-WINW “2 eunByy

124
o00'000‘oo! 000'000'oL ooo'ode'y ac0'o0t aca‘or 000° OOL OL
T T T T ie)
E 4s
.

L 4 ot
in
. . ee qs 9
oe
ao
id m
. 70 ®
F a
° 5
L . je dl
i~]
. Q
Q
b edhiig= 1d 1% 2
7809} uy ‘eG pygq ey ye Ylpim jsuUeYyo Mojy-eseg = OM a
edhy (eusyew peg = WG _
L ezepe-(pxel Zoo's = A —__—| esuesaid yueqng= 80 Igo =
a@oueseid inoos Buysixg = SB qi
60} Ul UNPHM UrB}d-pooy eAnoeYya = Md ft
jee) Ul UIPIM aerd WinWXeW = Md a

L. . sueds jo lequny= dS =] OP

seaiBep uy ‘yorye jo ajBue mojg = ¥
L , dd * 9, 8M0 4g
. 7 = OX
. gr NG * go € * SA * go, Mdd * 2Md «dS + )Sh't
Li \ A 1 f os

Development, Verification, and Application of a Simplitied Method to Estimate Tota!-Streambed Scour at Bridge Sites In linais

10


Type 1 - Square Nose Type 2 - Round Nose

Type 3 - Cylinder Type 4 - Sharp Nose

OO

Type 5 - Group of Cylinders

D. Common pier shapes {adapted from Richardson and others, 1993)
Figure 8. Continued.

12 Development, Verification, and Application of a Simplified Method to Estimate Total-Straambed Scour at Bridge Sites in Hlinois


U.S. DEPARTMENT OF THE INTERIOR
BRUCE BABBITT, Secretary

U.S. GEOLOGICAL SURVEY
Gordon P. Eaton, Director

For additional information
write to:

District Chief

U.S. Geological Survey
102 E. Main St., 4th Floor
Urbana, IL 61801

Copies of this report can be
purchased from:

U.S. Geological Survey
Information Services

Box 25286, Federal Center
Denver, CO 80225


g9°

3
¢ < seer
om ; 262 0294
10L-~ aa, é a) ve
02 elo LMR Ha 3 ga

Ses ay 13823) e
40° 3 322, BA Tad ei farae7} 4
a Bang og 0808 Safe“ anga” Egy
ARPA (226824 g0bFys0d oe rete SAL Ag
05 anette teh ct gg Se tag BT

EXPLANATION

2&2 STREAM-GAGING STATION AND
MAP REFERENCE NUMBER -
(See table 2)

ce) 20 40 60 =MILES
ty

Oo 20 40 60 KILOMETERS

37°

Figure 13. U.S. Geological Survey stream-gaging stations in lilincis corresponding to flood fraquency/exceedance data.

Application of the Method = =—.33


ze TL"O¥61 suou 0097 auc o0s'07. “II ‘PUEPHIG 38 JOART EaTOTEDag OOOLEPSO 09.

Oz 08-1964 uot sce auou 962 “TH ‘pueing seau Aremgrn yea1Q JNO OO6IEPSO —-6E

91 94-1961 avon zoL suo 189 ‘TI ‘uous ze3u Arenqun 4805 SOT OSISEPSO BS

08 £6-V161 auow 008'1Z vou 0L'8I “TL Hodaoag ye taAry woTUOIeOe OOSSEPSO LE

st DL-ESOL auou o6t't euou £56 “TT MOpsUTNA MOU SIAID TPA) OOOSEPSO «9S
“[f] ‘euuearg:

Le Li-Ty61 eudu oe’ ouou o0E'zt eau Ya) POUVD MOpOq IOATY WM GOOOTPSO «SF

6s €6-SE61 auou 000'9T uou OTE “IT Yeaouvy] Jvau weary addy ooosirso | #S
TH ‘Puno

0% SL“DS6I avou 090°C auou 916 sayeog suau Areinqin 490%) [TAL O0SSTPSO ES

4 08-1961 auou 668 auou DEL “TL eI0N Seat saaTy addy Hog HNOg OSLETPSO = -zE
ai

o¢ 69-0¥GI LY6T 000‘! LP6L oor'0l {UH Hounog 1 Jonny eugTED yO SEA OOSSIPSD TS

9% £6-8961 auor o0s'el 6961 OE‘ “TIT ‘caupuousyy Jou roary BABUTSUIS OZRPTPSO OS

st 9477961 6961 6b8 6961 Ot “TT ‘vor, 1 autsey 880710 OOPLROVD = 6
‘JOQIEH

ras ZL-9S61 aucun 6lF 6961 Ose donputaa 18 Areyngin west FET OOELBObO ar

ti ZL76S61 anou O€0'T auou S76 “IT ‘AND punoyy reeu Aranqiy nodeg sop OOOPI9EO = LP

1% 91-9561 auou 09s nou Rr “|| ToD wou ArongIn YO OOLZISEO «9b

OL £6-6R61:LE-EZEL auou oop'et ouow OOLI “IL ‘euog yw Jonny ByIeD OOOTIIEO «SF

we T8-0S61 €L61 ORE ELT 016% “IIL ‘sBunrdg uoxrg zou ysaxQ BAG OOSIBEED aa
“Td ‘s8undg

9% 08-SS61 auow 068'1 suou oi9'T VOXICL eau I9TUT F[ePUTIO MT OOSSBEEO «EF

tal €6-0861 sa6l OLY'8 $861 O8TL “TH ‘21epuaID Te eA sede OOOSEECD «TY

% €6-8961 SB6I 008°FT SR6T 006'Z1 TIL ‘OMAAPpY eau YORI ASN] OSPPRECO TP

eI ZL-0961 ‘auow 968 uo TOL ‘I ‘Wonoung seou Areinqun youerg Youle OzszsECO OF

9 78-4961 auou 060° avon 0z0'T “ML ‘Aujenby rear yaar oeH OTSTBECO = 6E

9€ SL-OPEL auou 006'6¢ POETOSEL'ShEl ——«OOZ'E “IL woroune seau JoAry SUITES OOSTRELO BE

+1 78-6961 suo ose'z LL6t Ors'c “IJ ‘corey eau yaar) AysMG OLIZSEEO = LE
AU “SITGA STED

8 €6-9961 auou O9€'L nou 089'9 Rou JOARY SuTTeS Pog wring OIZEEO «ME
‘TI 2TAa0H

ww 08-6561 auou 109 696I Ses sean Areyngyn) yaar SUES TTT SZOZBEEO SE
Ti ‘UaAeH MON

Lh 94-0961 viel SOE, PLOL eee mou Arengin sary USeqUM, @TNFT QO9ISECO PE

ys £6-0F61 uo O0E'Lb 1961 00P'Ib “TL ‘TwueD Fe Isa USeqEM UNF] OOSTSEEO = EE

9b $6-6Z6L'TC-ST6LE1-606! O6sItI961 —_O0E'EE 066T'986T'196T 02°82 “HL ‘AND oudeyy 18 VOT NPIS OOSOBEEO CE

1€ 06°096T Q66ETS6T —00F'OT O66T'196T 0876 “TI ‘Seusoy Jeon YI] OSIOH SLPOBEED =—TE

Panuesqo picoa, pepesoxa ‘eauna ‘bau Papseaxe nino ‘bez UU UONRIS sequnn = (¢) “Bij 228)
sivek 40 poped SEM DOLO payysjom sem peyysiom yoNaS sequunu
JO°ON side, Woy 09 Bea, woy- @0uelejal
(oi) 0010 (s/,4) 09 dew
penuyuog—papesoxe

dlem SenjeA ueYyM siBeA PELEIOOSSE LYIM SICUIII{ Ul] SUC!TE}S BulBeb-weans Aening jeoi6ojoed ‘gf ye sebreyosip pool 1284-00} puke -OS jo epnyubey "2 a1qeL

21

Apnilcation of the Method


Development, Verification, and Application of a

Simplified Method to Estimate Total-Streambed

Scour at Bridge Sites in Illinois

By Robert R. Holmes, Jr. and Chad J.Dunn

U.S. GEOLOGICAL SURVEY
Water-Resources Investigations Report 95-4298

Prepared in cooperation with the
ILLINOIS DEPARTMENT OF TRANSPORTATION, DIVISION OF HIGHWAYS

Urbana, Illinois
1996


ov £6-8P6T suou o06‘oI auou 080'6 “TI ‘Proysundg ye yoo Suds QOsiLsso soe
£61 R6TGL“SLOTEL EC6T
08 STE-626LLE-SEGTZT-SO6T evel QOE'Le EP6T‘6L6L 008'th “TI ‘wowoary 8 Faary uourRBueg OOSPLSSO HOE
“Foysayooy,
ad €6-0S61 nou 09'0z suo one'sT Wow JoANY wouraBuBg Woy WINDS QODSLSSO —«EDE
81 $8-8961 auou ost’s auou 006'F. ‘TT ‘oauaed We 9221 SO OOBSLSSO ZOE.
. ZOrSPOLEFOLEE-ZEET “T ‘Preoury
lb O€-6Z6T5L7-ST6L'ZI-8061 Lot 000'1Z eLettését ooL't we JOATY UOUMABUBS FrOY FOG OOSSLSSO —«TOE.
it ZaOS6T ‘euou 0g" LS61 OL TT “TU ‘opuoyAey, weou YIU WL OOSPLSSO OE
“Ul ‘snmoyon
ze B-1S6E S61 OLz'9 OLGULSEI ase'y eau JaATY UOUTeBUES HOY YMOS QOOPLESO «66
ia Li 1S61 suo ooL'ez ‘SuOT 006'81 "TH AofeO Wau Jeary voUTRsueS OOSTLSSO «867
o1 B-L961 auou OEE auou oIz'9 "IT "eieary We YeurD spuounl OSPZLESO LEZ
‘TIL ‘opeanwoWy
1% 9L-9S61 auou 06 auou 08 Jwau Are ngiT] YOK} WOPTIM OOTZLESO «KT
se £6-S1GTE1-806T anon O0s‘6I Lz61 000‘ “IU ‘orjeonuoyy ze saapy UouTeBURS OOOTLESO «SBT
Te 8L-8h61 sI0U oor'or 9s6l OOr'rt "YM “WewOYRIA 78 JoAnY uoWEBUES OOOTLSSO a4
aI eSL61 9861 l6r 06619861 Eta “TE quesig rau omy Byg OBEOLSSO EBT
1 ZE-TL6T auou OL2% uo 0907 “TI wwetig resu y2arD SIE OLEOLSSO = COZ
1% 22161 LR6Los6T = LPT £861°9861 61z “II ‘wredag eau yousig UXTPAT O9E0LSS0 T6z
$I 99-7261 suou obec ¥L6L 010% Ww IX OSEOLSSO —O6Z
tL S6GISTLI“OIGT euou Q06'RE S661 PLOT PZ6L O0r're TAag 8 JoATY UOOdS OOOOLESD —68Z
St Q8-9S61 suou OST L961 Ds] «=I ‘ounsniny yg ye Araingin yeory repay SzR6ISS0 —BBZ
is EEE El veel o09'se PLOLSRET oor'0e “IN SIAL wopuET We z04py UoodS OOSEISSO = L8Z
ot 9L-1961 euou us uot a7 “WI BHO, sWau ArEgu Hoary MINUET OSEBISSO «9B
ve £60961 Lt oeL's viol oee'y “TL ‘Burumok yy Jeau yearD uepUT OORBISSO = S8Z
ul EL-9S6I uot 912, U0 68t ‘Ty voued Teau yaary Yon OSGBOSSO PAZ
€s E6°1761 suou 09°66 auou 00F'%6 “TI ‘sauqpy uosBury 38 TOATY SOUTIT] GOSROSSO EBT
Ik £6°0961'85-7261 £861 OOS‘LP €861°086) 000'8¢ TIL ‘Aa]TeA Us2N WAU JOATY MBUPIIEWY OOOLOSSO «TAZ
a 1L-0961 auon 269 3u0u 009 “TH 2qepadoy zedu Aremqun Year UEIPU] OsLISSO TRE
or £6°SP61 £861 QOTILE —-LBGTIERET‘OREI‘IS6T —O00'TE TH ‘afpfazeBu03 seou reary MaUPIOZW OOSLISSO OBZ
vy £6-0561 1S61 0s6'6 1S61 Ole “TH ‘omg Te eau yar Javed OOOLISSO LT.
&e 28-0561 Is6t ozs'¢ 161 07g't “TL ose 1g 8 399K soured Yours a o0ss9sso LZ
“TH ‘Korpt
4 ZL-OS61 TS6I Q00'T 1861 mg amau YoarD Jom You ISA OOOIISSO LL
“TH WOETWOOTE
4 85-6661 uo Orz'z eucu ret ONE] sage Hoa AFI ONOSISSO —«9LT
peniesqo puogel pepesoxe = erino‘bay enino “hay eweU UOITEIS: sequinn = (et ‘By ea)
eeed 40 po}ied SBM OOLD paubem pelydiom Ones sequinu
4O'ON BIseA wou} woy- eOUelajes
{87} 0010. (si) 090 dew

poenunuog—papseaxe
uj suns BujSeB-weeas Aening [Ro|Go}OeD *g’N 78 sebasyosip pooy week-O01 pus -O¢ Jo epnyubeyy *Z SIGeL

QJoM SONIA UBYM sJeBA PETEIOSBE YIM SIO

29

Application of the Method


Data-Collection Sheet
plified Method for Bridge Scour Estimation
FOR USE WITH MULTI-SPAN BRIDGES ONLY

FIELD PARTY_J Ln County. Date_ 5-3 /-95
Structure Number_4/8 4 Feature CrossedEmbarass River

Facility Carried_County Road 300N Location County Rood 300N__ 1400 E

TO BE COMPLETED IN THE FIELD OR

FROM TOPOGRAPHIC MAP
Flood-Plain Width For 100-Year Flood. 375 feet
(FPW)
Base-Flow Channel Width @bridge 14 feet
(CWB)
Base-Flow Channel Width 1 Bridge feet
Length Upstream (CWU)
Bridge Length From (BW) 125 feet
Abutment to Abutment
Number of Spans (SP) 3.
Slope Of Channel in Vicinity 0.00031 feevffeet
of Bridge Site (S)
Cutbank Presence (CB) 2

(None-I, Slight-2, Extensive-3)

Existing Scour Near Picrs/Abutment (ES) 1
(None-1, Slight-2, Moderate-3, Extensive-4)

Pier Type (1, 2, 3, 4, 5, .. . see instructions) |

(PT)

‘Angle of Flow Attack on pier (A) _o
Maximum Pier Width (PW) 2.25 feet
Low Steel To Bed Distance (LSTB) 1A feet
Bed Material (BM) 4

(Cobbles—1, Clay-2, Gravel-3, Sand/Gravet-4,
Silt/Clay-4, Sand/Silt-4.5, Sand-5)

Information Entered Into Computer Program On_!O - 26-45

Entered By__ fe. fe. bt
Estimated Scour__24..7.93 ft

Figure 17. Sample of a completed multi-span field and office data-collection sheet for County Road 300 North bridge
over the Embarras River near Pesotum, Ili.

38 Development, Verification, and Application of a Simplified Method to Estimate Total-Streambed Scour at Bridge Sites In Iinois


08 £6161 L861 006". OLeL “II ‘opIssaAny TB OAR soure]d Se QOSTESSO ool
wo EG-TS6T L861 6 O66TL86T786L Obs TH ‘pooajag Je yeaxy WosIppy GOOZESSO 6ST
Ot 08-1961 suou 06h suo OLF “I ‘SYeNPION 3 YaazD uosippy GORTESSO SST
8b €6-9r61 O66 1°L861 008'z 0665°L861 OST “TTT ‘s8undg wroysepy 1? FAD NES OOSTESSO Est
Te GL-DOST'LSET'SSOT-OS6T8F5L amou OLs'T auou oss'T “TL HOI FEO 38 Y9OHD NES OBETESSO 9ST
686 F°08°096T
9% ‘LEGTSSELOS6L'SP6T ZLOL Ovi‘ TL6T O61 TN “ismnytoy Fe YU Nes OOETESsO SST
1Z QLO96TLEGISS6TOS6L' SPT TLOT Osi CLOT OoLT “TI ‘vostppy tae WS OOZIESSO PSI
“TH “e2seaL
él 6L-1961 ZL6T WL tL Leo ye anuoay jnupeay 18 yooIg Suds OETTESsO est
174 6L-9861 tL61 Lt 2161 z6r “TL Weurpay Te Year weysesy] OOTTESSO cI
61 6L7 1961 tL61 6bS CL61 Lip “TI ‘d[epSumuooyg 38 Yoorg Suds OROTESsO IS
124 6L-O96T'LEGT'SSEL uu OLo'z auou Org't “TIL ‘21 poo, Jesu YaatD YES OSOLESSO Ost
9% OL-IS6I 9u0u O9E'T u0u OUT “TIL SIYSt9 UOBUTTTY TEU FsArZ YES OOOTESSO 6F
0% €6-PL6T L861 ost 6861-4861 ont “TIE SSMOpeay ZuJoU Te FAD UPS OGGOESSO 8rl
6L 6L-1961 suo 696 uou 1s8 “Vil ‘ounEled Feau Yo yes OOGOLSSO Lbt
0% 08-1961 auow €Ls tL6T eas Tn “SUnElR 12 FOND UES OPGOESSO orl
i 114 OL-PS61 suon ase's S00n 0s0's “TL ued [sero] 4 JOATY SOUTP]d S9q. OOBOESSO SI
<4 O8-19°SS61 Suu C6L. CLE ObL “HL Wed SSAA] Te ASAT ASATIS GOLOESSO Pl
Br LL-0961 nou 68°F euou 079'F [M1 ‘9403 Joana 1 JaARy sourB{d 89. QOSOESSO trl
i<4 GL T96T'LS6LSS6L suou Olle ouou tra “TIL 258[d PIEqIO 2 eer) MOTTA OBPOESSO rags
61 : 6L-1961 uo 19 auou oes “qn qeedsoug tunopy wa yoorD SUIBIT OOPDESSO —— LT
| 4 £6°1S6T suou 006'T auou OL'T TH ‘souretg sacl ye F224D JaTTEM O0ODESSO OvT
\ 61 61-1961 quou OCLT uou O6+'T “I edsorg UNO! We AAD ISTIAM 006EZSSO eT
i Or TOESET auow 0€6 L861 08 “TUL ‘eadsorg yunoPY IuaU yA PReUOoW OOS6ZSSO BEL
y 1% GL-T96TLSELSSOL uot 908 LS6E $69 “TT ‘SureayAy Feau Year PUA OOE67SSO cel
+S E6-T POL BE6T avon Ors LR6T-8E6T oos'p “TH ‘SoUre]g Soc] Tau JOATY SAUTE] SCT OOOGTSSO oct
Ir t6-ES61 9u0u Ort ouou p26 “IT ‘Saryooy A Jou Hoar) OTM OOSRZESO set
oF 94-1961 euou rath euou £b9 "IN 2A03 BuO] 18 Yoo] OEYNA OLP8ZSSO vel
or 9L-1961 ouou £87, euou Ose “HL young, aye] tea Yoon) OBA OPbEZSSO €ET
u LETLOVOL-696 L9G 1E9- C961 auou Ors'b euou ost'r TH ‘Suraouy We Jeary SaureTY $e OOFEZSSO Zel
OL 9L-T961 euou ver TLEL Sle “TT oispyeady 38 year oisprendy o9¢8zZss0 Tel
€6-0661'9L-EL61
at SPL-LOGT*S9-E96 119-0961 auow OL suOu a0s'L “TH MOT, Of Je FOAD URTPUT GEZRZSSO Oct
“HL “UTS [>puRA,
or 9L-1961 Su0U 659 euou ois Jeo You eseuleIq WOMMeL] OOZRTSSO 6et
91 9L-1961 euou tel Sgou 027 TO ‘WoTepUNA 3B UTIG oxe'] uote OLISTSSO R21
ral 94-0961 ou0U O67'T Q961 Ov TL exe] puourviq 18 YAID URIPUL OSTSZSSO Lat
i id E6-Db6T 9861 Ore 9861 07's ‘PIT ‘s0uANE FOU TOALY SAUIid SAT ONO8ZSSO 971
| pesesgo pucoes pepesoxe  edino "bey Papesoxe @aino ‘bay eweU UORES sequinn § (e1 By 29s)
| sune@A je poped sem 0010 payysjem uM peywdjem USNs aequind
JO°ON s1ae, Woy ogy sige, wo eousieyes
(3/4) G01. igase dew
Hl penuyuog—pepasoxs

@jam Sanjen USYM ssBed Poyeoosse YUM S|OUIIT] Ul SUO!ETS BulGeb-weens Aering jeoiBojoed ‘s'n 18 sableyosip poo) 204-00) PUe -OS JO epnyubey ‘2 SIqeL

Development, Verification, and Application of a Simplified Method to Estimate Total-Streambed Scour at Bridge Sites In Illinois:

24


000'000' ooo'o!

0b

es2e-(2x)y z9ge'9 = A,

x
000'01 000")
T 7
* .
. . . «
oon . oe
. . .
eee
eae ° .
*
.
°
° oe

3064 u ‘eBpugq
6U3 18 YIDIM JOUUBYO Moy-eseg = GMO
ed{ jepeyew peg = We
edfy juewingy = LY
368} U} ‘BQUEISIP Poq o} |ea15 MOT = ALS7
puoses sad yea;
o1qno uy ‘eBiwyos|p pooy se84-o04 = O

amo :
qoMla+ ive aists mas «, DX

1 4] seus 26pud 40) potyou jeUO_UeAUOD eU] YIM peTeUUNSe NODS 4240} 30) Z BAND Bdo}eAUB URdS-eIBUIS “g olny

4334 NI ‘YNOOS GALVWLLS2 91-O5H

Devefopment, Verification, and Application of a Simplified Method to Estimate Totat-Streambed Scour at Bridge Sites in illinois



Abutments

-

BW

EXPLANATION

a Flare ratio, based on
individual engineers
judgement

BW Bridge length

CWB Base-fiow channel
width at the bridge Base-Flow

Channel
GWU Base-fow channel
length one bridge
fength upstream

FPW Effective flood-ptain A Plan view of bridge site
width

Bridge deck

‘Low steel

EXPLANATION Low steel to bed distance (LSTB)

A Flow angle of attack ¥

Pier width (maximum)

B. Plan view of pier and associated . . .
angle of attack of flow Cc. End view of bridge site

Figure 8 Plan view and detail of bridge site and characteristics tor a hypothetical bridge site.

Simplified Mathod to Estimate Total-Streambed Scour

abe