FLOOD04125

• County: Statewide
• Basin: Statewide
• Title: Interim Procedures for Evaluating Scour at Bridges
• Date: 9/1/1988
• Prepared By: Federal Highway Administration
• Floodplain - Doc Type: Educational/Technical/Reference Information

EXHIBIT III-B, I of 2

SCOUR PREDICTION EQUATIONS AS' PER FHWA DRAFT ADVISORY

TIllS PROGRAM WILL GENERATE CONTRACTION AND LOCAL - ABUTMENT
AND PIER SCOUR DEPTHS FOR HOST CASES. RELIEF BRIDGE CASES WILL
NOT IlORIC. .

INPUT THE DATA KNOIIN FOR DIE CASE. IF NOT APPLICABLE INSERT 'N/A'
IF TIlEN AN ERROR 'ERR' IS INDICATED mIS SHOUlJ) BE INVESTICATED
AND GENERALLY IGNORED.

TIlE RELATIONSHIP BETWEEN SHEAR STRESS TAU 1 AND TAU C lIAS
NOT BEEN USED IN TIlESE COMPUTATIONS. AND mEREFORE IT IS TIlE
RESPONSIBILTY OF mE TECH/ENGINEER TO DETERMINE WHETHER TIllS
IS APPLICABLE OR NOT IN ANY INDIVIDUAL SITUATION.

INPUT mE DATA ON TIlE NEXT PAGE - "PgDn" KEY.
****BE SURE TO PRESS "F9" TO CALCULATE mE WORlCSHEET BEFORE PRINTING
TIlE LAURSEN AND TOCH EQUATION IS NOT GIVEN IN mE FHWA ADVISORY.
INPUT TIlE DATE STARTING WIDI MONTH EG 'MAR'
IN CASE AN ERROR MESSAGE APPEARS PRESS "Esc" AND RETYPE.
TO CALCULATE "F9" TO PRINT DATA" A1t I" TO PRINT RESULTS" A1t P

TITLE : BRIDGE. 6622 DATE: Jul-88
ALL INPUTS @ DISCHARGE: Q50 Q100 Q500
IF LEFT FLOW IS OVERBANK (CASE 4),
ENTER 1 OTHERWISE ENTER 2 1 1 1
IF RIGHT FLOW IS OVERBANK (CASE 4),
ENTER 1 OTHERWISE ENTER 2 1 1 1
LEFT OVERBANK FLOW DISCHARGE Qo 120 149 419
LEFT OVERBANK FLOIl DEPTH Yo 1.20 2.00 5.10
WIDm OF !fAIN CHANNEL 1011 57.00 59.00 60.00
RIGHT OVERBANK FLOW DISCHARGE Qo 116.00 130.00 269.00
RIGHT OVERBANK FLOIo1 DEPTH Yo 2.20 3.00 6.10
FLOW IN !fAIN CHANNEL Qc 1350 1600 2500
CONTRACTED SCOUR INPUTS
WIDm OF !fAIN CHANNEL 1011 57.00 59.00 63.00
Io1IDm OF CONTRACTED CHANNEL 1012 54.00 55.00 58.00
FLOIo1 IN CONTRACTED ~rlANNEL Qt 1586 1879 3188
FLO\J IN !fAIN CHANNEL Qc 1350 1600 2500
IlANNING FOR CONTRACTED CHANNEL N2 0.05 0.05 0.05
IlANNING FOR !fAIN CHANNEL N1 0.05 0.05 0.05
ABUT 6. PIER SCOUR INPUTS:
ABUT AND EMBANK. LENGTH RIGHT Al 4.90 4.60 5.00
ABUT AND EMBANK. LENGTH LEFr A2 3.30 3.50 4.10
UPSTREAM VF.T.OCITY V1 4.70 5.00 5.60
AVERAGE UPSTREAM FLO\J DEPTH Y1 8.90 10.00 13.50

PIER Io1IDm B 3.00 3.00 3.00
C FACTOR FOR PIER SHAPE 1(1 0.90 0.90 0.90
C FACTOR FOR FLOW ANGLE 1(2 1. 00 1.00 1. 00
ENTER 1 FOR SPL SLP ABUT, 2 FOR VERT 2 . 00 2 .00 2.00
PRESS "N" KEY TO PERFORM COtlPUTATION NOll I "F9"

FOR LAURSEN AND TOCH EQUATION SOUlTION:
I( SIGKA 1tE 1.00 1.00 1.00
I( SHAPE kS 0.80 0.80 0.80
FLOll DEPTH APROACH PIER Yo 9.20 10. 00 13.10
_PRESS "F9" KEY AGAIN TO PERFORM mIS CALCULATON.

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