NYSDOTNYSDOTBRIDGE SAFETY BRIDGE SAFETY

ASSURANCE PROGRAMASSURANCE PROGRAM

HYDRAULIC VULNERABILITYHYDRAULIC VULNERABILITYASSESSMENT ASSESSMENT

IMPLEMENTATIONIMPLEMENTATIONAND MONITORINGAND MONITORING

HYDRAULIC VULNERABILITYHYDRAULIC VULNERABILITY

Overview of the HydraulicOverview of the HydraulicVulnerability Assessment ProcessVulnerability Assessment ProcessFHWA Item 113 CodesFHWA Item 113 CodesMonitoringMonitoring

FloodwatchFloodwatchPost Flood InspectionPost Flood Inspection

HYDRAULIC VULNERABILITYHYDRAULIC VULNERABILITYApproximately Approximately 60% of bridge 60% of bridge failures are due failures are due to hydraulic to hydraulic forces.forces.

Catastrophic Catastrophic Partial Partial CollapseCollapseStructural Structural DamageDamage

HYDRAULIC VULNERABILITYHYDRAULIC VULNERABILITYSchoharie Bridge Schoharie Bridge Failure Failure -- April 1987April 1987

Technical AdvisoryTechnical AdvisoryT 5140.20 T 5140.20 ---- 19881988Technical Advisory Technical Advisory T 5140.23 T 5140.23 ---- 19911991

New bridgesNew bridgesdesigned for scourdesigned for scourEvaluate existing bridges for scourEvaluate existing bridges for scour

23 CFR 650.313.e.323 CFR 650.313.e.3 ---- 20052005

HYDRAULIC VULNERABILITYHYDRAULIC VULNERABILITYASSESSMENTASSESSMENT

1.1. ScreeningScreening2.2. Classifying Classifying 3.3. RatingRating4.4. Plan of ActionPlan of Action

MonitoringMonitoring

HYDRAULIC VULNERABILITYHYDRAULIC VULNERABILITYASSESSMENT (HVA)ASSESSMENT (HVA)

1.1. Screening Screening –– Prioritize bridges toPrioritize bridges toproceed with HVAproceed with HVAassessment. assessment.

Was not done for local bridges Was not done for local bridges

HYDRAULIC VULNERABILITYHYDRAULIC VULNERABILITYASSESSMENTASSESSMENT

2.2. Classifying Classifying ---- Evaluates the Evaluates the vulnerability of avulnerability of astructure to scourstructure to scourfailure.failure.

General Hydraulic AssessmentGeneral Hydraulic AssessmentFoundation AssessmentFoundation Assessment

HYDRAULIC VULNERABILITYHYDRAULIC VULNERABILITYASSESSMENTASSESSMENT

2.2. Classifying Classifying –– General Hydraulic General Hydraulic AssessmentAssessment

Streambed MaterialStreambed MaterialRiver SlopeRiver SlopeHistoric Scour DepthHistoric Scour DepthAdequate OpeningAdequate OpeningChannel BottomChannel BottomChannel ConfigurationChannel Configuration

Refer to binderRefer to binder--Session #2Session #2--for detail form for detail form

HYDRAULIC VULNERABILITYHYDRAULIC VULNERABILITYASSESSMENTASSESSMENT

2.2. Classifying Classifying –– Foundation AssessmentFoundation AssessmentAbutments and PiersAbutments and Piers

Existing Scour Existing Scour CountermeasureCountermeasureFoundation TypeFoundation TypeCulverts Culverts ---- Less susceptibleLess susceptible

to scour damage?to scour damage?Refer to binderRefer to binder--Session #2Session #2--for detail form for detail form

CLASSIFICATIONCLASSIFICATIONFinal General Foundation

Classification = Hydraulic + Assessment Score Assessment Score

Higher of the Abutment and

Pier Scores

Refer to binder-Session #2-for detail form

HYDRAULIC VULNERABILITYHYDRAULIC VULNERABILITYASSESSMENTASSESSMENT

2.2. Classifying Classifying –– Vulnerability ClassVulnerability Class

Classification Classification ScoreScore < 25< 25 20 20 -- 4040 >35>35

VulnerabilityVulnerabilityClassClass

LOWLOW MEDIUMMEDIUM HIGHHIGH

Refer to binder-Session #2-for detail form

HYDRAULIC VULNERABILITYHYDRAULIC VULNERABILITYCLASSESCLASSES

1.1. LOW LOW ---- Bridge has little potential for failureBridge has little potential for failure..

2.2. MEDIUM MEDIUM ---- There is a recognizable potentialThere is a recognizable potentialfor failure from several stormfor failure from several stormevents. events.

3.3. HIGH HIGH ---- The occurrence of a single intermediateThe occurrence of a single intermediateor large flood could result in failureor large flood could result in failure..

HYDRAULIC VULNERABILITYHYDRAULIC VULNERABILITYASSESSMENTASSESSMENT

3.3. RatingRating –– Provide a uniform measureProvide a uniform measureof the structureof the structure’’s vulnerabilitys vulnerabilityto failure.to failure.

VULNERABILITY RATINGVULNERABILITY RATINGPROCEDUREPROCEDURE

BridgeClassification

ExposureTrafficVolume

Funct.Class

Failure Type

Likelihood Score Consequence Score

Vulnerability Rating

High-10Medium-6

Low-2

VULNERABILITY RATING SCOREVULNERABILITY RATING SCORE

RatingRating Rating ScoreRating Score> 15> 15 11 Safety PrioritySafety Priority

13 13 -- 1616 22 Safety ProgramSafety Program9 9 -- 1414 33 Capital ProgramCapital Program

< 15< 15 44 Inspection ProgramInspection Program< 9< 9 55 No ActionNo Action

Refer to binder-Session #2-for detail form

FHWA Item 113 CodeFHWA Item 113 CodeScour Critical BridgeScour Critical Bridge

Foundation of abutment or pier is unstable Foundation of abutment or pier is unstable due to observed, calculated or assessed due to observed, calculated or assessed scour depth.scour depth.

FHWA 113 Code FHWA 113 Code -- Scour Critical BridgeScour Critical Bridge

‘‘00’’ = Bridge has failed and is closed to= Bridge has failed and is closed totraffic.traffic.

FHWA 113 Code FHWA 113 Code -- Scour Critical BridgeScour Critical Bridge

‘‘11’’ = Field review indicates that failure of piers= Field review indicates that failure of piersand/or abutments is imminent. and/or abutments is imminent. Bridge is closed to traffic.Bridge is closed to traffic.

FHWA 113 Code FHWA 113 Code -- Scour Critical BridgeScour Critical Bridge

‘‘22’’ = Field review indicates that extensive = Field review indicates that extensive scour has occurred at bridge scour has occurred at bridge foundations. foundations.

FHWA 113 Code FHWA 113 Code -- Scour Critical BridgeScour Critical BridgeSpread on Earth Supported on Piles

AssessedScour Depth

Are Piles Stable?

‘‘33’’ = Bridge foundations determined to be = Bridge foundations determined to be unstable for assessed or calculated unstable for assessed or calculated scour conditions.scour conditions.

FHWA 113 Code FHWA 113 Code -- Scour Critical BridgeScour Critical Bridge

‘‘77’’ = = Countermeasures have been installed to Countermeasures have been installed to mitigate an existing problem with scour mitigate an existing problem with scour and to reduce the risk of bridge failure and to reduce the risk of bridge failure during a flood event. during a flood event.

FHWA 113 Code FHWA 113 Code Scour Critical Bridge reScour Critical Bridge re--coded to coded to ““88””

‘‘88’’ = = Bridge was analyzed, countermeasure hasBridge was analyzed, countermeasure hasbeen designed and installed to mitigate all been designed and installed to mitigate all existing and potential scour conditions. existing and potential scour conditions.

FHWA 113 Code FHWA 113 Code -- Scour Critical BridgeScour Critical Bridge

‘‘UU’’ = = ““UnknownUnknown”” foundation that has not beenfoundation that has not beenevaluated. evaluated.

HYDRAULIC VULNERABILITYHYDRAULIC VULNERABILITYASSESSMENTASSESSMENT

4.4. Plan of ActionPlan of Action(POA):(POA):23 CFR 650.313.e.323 CFR 650.313.e.3Scour Critical Scour Critical bridgesbridgesDetour routeDetour routein placein place

HYDRAULIC VULNERABILITYHYDRAULIC VULNERABILITYASSESSMENTASSESSMENT

4.4. Plan of Action Plan of Action (POA): (POA):

Scour RetrofitScour Retrofitand and

CountermeasuresCountermeasures-- HEC 23HEC 23

A properly designedA properly designedand installedand installedcountermeasure cancountermeasure canremove a structureremove a structurefrom the POA.from the POA.

HYDRAULIC VULNERABILITYHYDRAULIC VULNERABILITYASSESSMENTASSESSMENT

4.4. Plan of Action:Plan of Action:Monitoring Monitoring ---- Flood WatchFlood Watch

---- Post FloodPost FloodInspectionInspection

Plan of ActionPlan of ActionMonitoring: Floodwatch Monitoring: Floodwatch

Post Flood InspectionsPost Flood Inspections

What ?What ?When ?When ?Who ?Who ?Where ?Where ?How ?How ?

MonitoringMonitoringFloodwatch Program Floodwatch Program -- What bridges?What bridges?

Classification ScoreClassification ScoreHighHighMedium, based on recommendation by RHEMedium, based on recommendation by RHE

FHWA Item 113 CodeFHWA Item 113 Code““22””““33””Maybe Maybe ““UU””

Rating ScoreRating Score1 and 21 and 23, based on RHE recommendation3, based on RHE recommendation

MonitoringMonitoringFloodwatch Program Floodwatch Program -- What bridges?What bridges?

Bridges flagged by inspectors for scour Bridges flagged by inspectors for scour damage.damage.

MonitoringMonitoring

Floodwatch Program Floodwatch Program -- When?When?

During Flood Warning issued by the During Flood Warning issued by the National Weather Service (NWS). National Weather Service (NWS).

During Flash Flood Warnings????During Flash Flood Warnings????

Reports of flooding from local Reports of flooding from local residents and/or maintenance crew.residents and/or maintenance crew.

MonitoringMonitoringFloodwatch Program Floodwatch Program –– WhoWho……

……determines what bridges are on the determines what bridges are on the Flood Watch Program?Flood Watch Program?

……receives notification of Flood Warnings?receives notification of Flood Warnings?……carries out the Flood Watch?carries out the Flood Watch?……carries out Post Flood Inspections?carries out Post Flood Inspections?……reopens a bridge after it was closed asreopens a bridge after it was closed as

a result of Flood Watch? a result of Flood Watch?

MonitoringMonitoringFloodwatch Program Floodwatch Program -- Where?Where?

GIS database of Scour Critical bridgesGIS database of Scour Critical bridgesTrack storms using satellite imageryTrack storms using satellite imagery

InternetInternet

MonitoringMonitoringFloodwatch Program Floodwatch Program -- How?How?

Continual MonitoringContinual MonitoringHigh Risk bridges: Potential to have a High Risk bridges: Potential to have a sudden or catastrophic collapse.sudden or catastrophic collapse.

MonitoringMonitoringFloodwatch Program Floodwatch Program -- How?How?

Periodic Monitoring:Periodic Monitoring:NonNon--High Risk bridges: Bridges that will High Risk bridges: Bridges that will undergo structural damage/partial undergo structural damage/partial collapse as collapse as a result of a result of substructuresubstructuremovement.movement.

Flood Watch ProgramFlood Watch ProgramInspection Procedures:Inspection Procedures:

Flood Warning Inspection ReportFlood Warning Inspection Report–– Critical ItemsCritical Items

AlignmentAlignmentTiltTiltVibrationVibrationFreeboardFreeboardSnagging DebrisSnagging DebrisBridge NoiseBridge NoiseSuperstructure DistressSuperstructure Distress

Flood Watch ProgramFlood Watch ProgramInspection Procedures:Inspection Procedures:

Flood Warning Inspection ReportFlood Warning Inspection Report–– NonNon--Critical ItemsCritical Items

LengthLengthErosionErosionSettlementSettlementCrackingCrackingDebrisDebrisImpacting DebrisImpacting DebrisFlow CharacteristicsFlow CharacteristicsStream NoiseStream Noise

Critical ItemsCritical Items

AlignmentAlignment–– VerticalVertical–– HorizontalHorizontal

• Any change inalignmentshould result inbridge closure.

Critical ItemsCritical ItemsTiltTilt–– Plumbness ofPlumbness of

piers and piers and abutments abutments

–– Change of Change of inclination of inclination of bearingsbearings

• Any changeshould result inbridge closure.

Critical ItemsCritical ItemsVibrationVibration–– Check for Check for

vibration or vibration or swaying motion swaying motion from stream from stream flow. flow.

• Any noticeableamount shouldresult in bridgeclosure.

Critical ItemsCritical ItemsFreeboardFreeboard–– Zero freeboard or overtopping is cause Zero freeboard or overtopping is cause

for immediate closure.for immediate closure.

Critical ItemsCritical ItemsFreeboardFreeboard–– Critical freeboard or water depthCritical freeboard or water depth

Critical ItemsCritical ItemsSnagging DebrisSnagging Debris–– Any noticeable amount of snagging Any noticeable amount of snagging

debris caught along the structure is debris caught along the structure is cause for immediate closure.cause for immediate closure.

Critical ItemsCritical ItemsNoiseNoise–– When there is no traffic, listen for creaks, When there is no traffic, listen for creaks,

groans, snapping, or popping noises coming groans, snapping, or popping noises coming from the bridge.from the bridge.

NonNon--Critical ItemsCritical ItemsLengthLength–– An increase or decrease in bridge length, An increase or decrease in bridge length,

measured at the deck or curb joints.measured at the deck or curb joints.

NonNon--Critical ItemsCritical ItemsErosionErosion–– Check approach roadways, embankments Check approach roadways, embankments

slopes, shoulders, and pavement for erosion.slopes, shoulders, and pavement for erosion.

NonNon--Critical ItemsCritical ItemsSettlementSettlement–– Check approach roadways, embankments Check approach roadways, embankments

slopes, shoulders, and pavement for slopes, shoulders, and pavement for settlement.settlement.

NonNon--Critical ItemsCritical ItemsCrackingCracking–– Look for cracking in pavement, shoulder Look for cracking in pavement, shoulder

areas, and embankment slopesareas, and embankment slopes..

Flood Watch ProgramFlood Watch ProgramReopening a closed bridge as a Reopening a closed bridge as a result of a flood watch.result of a flood watch.

The bridge can only be reopened with the approval of a Professional Engineer registered to practice in New York State.

Post Flood Inspection ProgramPost Flood Inspection ProgramAll bridges on the Floodwatch ProgramAll bridges on the Floodwatch ProgramFHWA Item 113 Code FHWA Item 113 Code ““77””, , ““UU””Recommended by RHERecommended by RHEShould be done as soon as flood water Should be done as soon as flood water recedes (or within 2 Weeks)recedes (or within 2 Weeks)Scour DamageScour Damage–– Should be retrofitted ASAPShould be retrofitted ASAP–– If not, bridge should be included on theIf not, bridge should be included on the

Floodwatch Program (if not already on it)Floodwatch Program (if not already on it)

Post Flood Inspection ProgramPost Flood Inspection ProgramBridge Pier

Post Flood Inspection ProgramPost Flood Inspection ProgramBefore Flood

Post Flood Inspection ProgramPost Flood Inspection ProgramAfter Flood

Post Flood Inspection ProgramPost Flood Inspection ProgramScour Repair Completed

QUESTIONS ???QUESTIONS ???

Lallman RambaliLallman RambaliRegional Hydraulics EngineerRegional Hydraulics Engineer

NYSDOT Region 5NYSDOT Region 5125 Main Street125 Main StreetBuffalo, NY 14203Buffalo, NY 14203Phone: (716) 847Phone: (716) 847--32023202EE--mail: mail: Lrambali@dot.state.ny.usLrambali@dot.state.ny.us