Bridge Assessment Methods Using Image Processing · PDF fileBridge Assessment Methods Using...

April. 2013

Masato Matsumoto

Bridge Assessment Methods Using Image Processing and Infrared

Thermography Technology

1. Background2. Non-destructive Bridge Assessment Method3. Practical Application Pilot Projects4. Summary and Conclusions

Presentation Outline

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Traditional and New Approach

New Technology

High Definition Video Digital Camera Infrared Camera

Snooper Truck Bucket Truck Hammer Sounding

Traditional Approach

Typical Traditional Inspection Result

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Current Practice for Documentation of Inspection Results – Worded descriptions transcribed by hand.

More efficient, objective and safer bridge inspections can be realized only through technological improvements.

Long-Term Bridge Monitoring

An objective digital record is essential for monitoring long-term bridge performance and maintenance budget planning.

Year 2012 Year 2014 Year 2016 Year 2018

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Infrared Imagery TechnologyC

oncr

ete

surfa

ce te

mp.

(°C

)

morning

Sound area

Noon evening night

Temp.differences

Concrete surfaceHeat flow

Imagery Period A

Imagery period B

Imagery Period A

Air temp.

Inner Crack

Delaminated areaSound areaDelaminated area

Sound area

Imagery Period B

Delaminated area

Concrete surface

Heat flow

Heat flow Heat flow

Inner Crack

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Interpret Thermal Data into Damage Ratings

Damage Rating Definition

Crack Location RatingDamage Rating

Temp. Distribution

rebar

Concrete surface

Tem

p.（℃）

Depth�4㎝

Reaching surface

crack Indication

Caution

CriticalEmergent Action Required

crackrebar

Depth�2㎝

crack

rebar

Concrete surface

Concrete surface

Concrete surface

Tem

p.（℃）

Tem

p.（℃）

Concrete surface

Concrete surface

Automatic Camera System (ACS)

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8

Photographing by HDV

#3#2#1

Combined Image of full surface continuity

Camera

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Deck Top Scanning System

4.0 m

80 km/h(50mph)

GPS

Speed meter

Line sensor cameraIR cameraGenerator

2.6 kVA

Line sensor : 0.8 mm/pixel @ 50mph, Width = 4.0m→ detectable crack width = 0.2 mm

Color images are acquired

PC

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Advantages of New Inspection Technologies

Overcome some shortcomings of human subjectivity Providing an objective digital record for historical

inspection data comparisons and maintenance budget forecasts.

Reducing time for documentation of current bridge condition (Improve efficiencies in bridge inspection resource application).

Identifying areas of bridges to be targeted for closer inspection and/or future monitoring.

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Pilot Project in Florida

Government

IndustryAcademia

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Pilot Project Location

● FDOT District 5● UCF

● Bridge SR#5

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ACS Photographing (Deck Underside)

Deck #5

Deck #6

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Evaluation by FDOT Bridge Inspector

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Crack Widths Evaluation at Deck Underside

Crack#1Crack#2-1

Crack#2-2

Crack#3-1

Crack#3-2

Crack ACS Crack Detection FDOT Inspector Match

Crack #1 < 0.010″ 0.006″ OK

Crack # 2-1 < 0.010″ 0.007″ OK

Crack # 2-2 0.010″～0.030″ 0.025″ OK

Crack # 3-1 0.010″～0.030″ 0.016″ OK

Crack # 3-2 < 0.010″ 0.010″ OK

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IR Test Piece at Deck Underside

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1cm

2cm

3cm

CRITICAL CAUTION OBSERVATIONOK OK OK

Detectable Depth

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Temperature Recorded at Deck #6 Underside

07/11 07/12 07/13 07/14

Thunderstorm Rain

Thunderstorm Rain

RainThunderstormThunderstorm Shine

07/10

Concrete

Air

@ Melbourne, FL

IR Inspection Results (Deck #6 Underside)

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Hammer Sounding Infrared ID # IrBAS Result Match

Plastic inside 607 Detected

South

North

(Minimum Detectable Scale = 4.4mm)Photographed at PM3:00, August 1,

CRITICAL CAUTION OBSERVATION601 4.31602 1.94603 1.51604 4.84605 2.15606 1.29607 0.11608 2.15609 0.54610 3.77611 0.32612 1.29613 1.29614 2.83615 0.55616 13.95Total 21.06 16.06 5.70

ID#POTENTIAL SPALL AREA (sq. ft.)

Hammer Sounding by FDOT

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Hammer Sounding by FDOT

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(Deck #6 Bridge Underside - #607)

#607Before hammer Sounding

#607After hammer Sounding

Plastic sheet appeared

(Thermography) (Software Output)

Deck Top Scanning for I-4 Bridges in Orlando

Traditional Technique and New Approach

ＢＲＡＮＤ ＢＯＯＫ 22

Deck Top Scanning System

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Infrared Camera Line Sensor Camera

Speed Meter

Infrared Deck Scanning

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I-4 over South Street Bridge West-bound

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Deck Surface Image (#750050 - WB) – 2nd lane

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Insignificant Moderate Severe

Crack Size < 1/16’’ 1/16’’ to 1/4’’ >1/4’’

Crack Map (1/64” (0.3mm) or Greater)Deck Surface Crack Map

Infrared Thermography Image

Infrared Software Output

East Side Span

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Lane 1

Longitudinal crack

Transversalcrack

Hexagonalcrack

Lane 2

Hexagonalcrack

Transversalcrack

Longitudinalcrack

Delamination Hexagonalcrack

Pot hole

Lane 3Transversal

crack

Lane 4No significant

crack

Delamination

Comparison between Visual and IR Images (3)

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Construction Joint between old deck and new additional deck at 2nd lane

Typical Cracking Pattern for Concrete Bridge Deck Surface

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Typical Cracking Pattern for ASR-Induced Concrete Bridge Deck (FHWA, 2011)*

Map Cracking, Discoloration and Possible Delamination on the Scanned Bridge Deck Surface

* Federal Highway Administration (FHWA, 2011), Alkali-Silica Reactivity Field Identification Handbook (FHWA-HIF-12-022)

‘Initially cracks are initiated close to the expansion joints and tend to be orientated perpendicular to the joint. As ASR advances, the cracks spread around the perimeter of the slabs and there is often little or no cracking in the center of the slab. The reason that the region around the joints is more prone to cracking is because (a) there is often more moisture available at the joints, (b) there is less restraint to expansion close to the joints, and (c) mechanical stresses to vehicular loading are higher at the joints’

Surface Pop-out of Aggregates

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‘Alkali-reactive aggregates undergoing expansion near the concrete surface may induce the detachment of a portion of the mortar overlying the aggregate and leaving the reactive aggregate exposed. Such features are termed ‘pop-outs’.’

* Federal Highway Administration (FHWA, 2011), Alkali-Silica Reactivity Field Identification Handbook

(FHWA-HIF-12-022)

Surface Pop-out of Aggregates on the Scanned Deck Top Surface

An Example of Exudation Associated with Cracks

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An Example of Exudation Associated with Cracks(FHWA, 2011)*

An Example of Exudation Associated with Cracks (Observed in the scanned deck underside)

* Federal Highway Administration (FHWA, 2011), Alkali-Silica Reactivity Field Identification Handbook

(FHWA-HIF-12-022)

‘Surface gel exudations are also a common feature of ASR. The exudation may be alkali-silica gel or lime (or both) leaching from the cracked concrete.’

Condition States Based on FHWA, 2012

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West (South) - bound

Element Level Condition State

1 (good)

2 (fair)

3 (poor)

4 (severe)

East side span Center span West side span

Lane 4

Lane 3

Lane 2

Lane 1

* Condition States Based on:Federal Highway Administration (FHWA, 2012), Alkali Silica Reactivity Surveying and Tracking

Guidelines (FHWA-HIF-12-046)

Deck Surface Distressed Area Calculation

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Insignificant Moderate Severe

Crack Size < 1/16’’ 1/16’’ to 1/4’’ >1/4’’

Crack Map (1/64” (0.3mm) or Greater)

Distressed Area

（Including Cracks > 1/16” (or 1.6mm) and/or Potholes

Deck Surface Distressed Area Calculation (Example)

Total Deck Area(ft2)

Distressed Area(ft2)

Percentage ofDistressed Area

(%)

2,099.08 48.16 2.3

NBI Condition State Description

Condition State 1(good)

The combined area of unsound wearing surface (spalls, delaminations, delaminated temporary patches) is 2% or less of the total deck area

Condition State 2(fair)

The combined area of unsound wearing surface (spalls, delaminations, delaminated temporary patches) is more than 2% but not more than 10% of the total deck area

Condition State 3(poor)

The combined area of unsound wearing surface (spalls, delaminations, delaminated temporary patches) is more than 10% but not more than 25% of the total deck area

Condition State 4(severe)

The combined area of unsound wearing surface (spalls, delaminations, delaminated temporary patches) is more than 25% of the total deck area

Prioritizing Bridge Repair/Rehabilitation Program

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Phase 1: Pre-Screening(Video Image)

Keep the Recorded Image

Flagged Spans

Not Flagged

Phase 2: Prioritization (Determine Deterioration Type)

Spans in Red Phase 3: Detailed Bridge Scan (from

Underside)

Deck Repair/Rehab Planning

Lane Span % of Distressed Area Condition State1 20.0 32 1.6 13 1.8 14 5.7 21 6.7 22 3.8 23 1.2 14 9.0 21 2.7 22 2.9 23 4.5 24 3.6 21 1.5 12 1.2 13 1.3 14 1.7 1

1

2

3

4

NBI Condition States

Corridor/Network Level Bridge Inspection

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1. The pilot application for bridge underside inspection in Florida was successfully finished.

2. The accuracy of the imaging and IR inspection technologies were evaluated by FDOT certified bridge inspector through traditional technique

3. Employing NDE deck top scanning systems can improve distressed area mapping accuracy, reduce inspection time and cost.

4. Applying deck scanning system to corridor-level bridge deck will allow transportation agencies to prioritize their bridge deck repair/rehabilitation program

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Special thanks to..Florida Department of Transportation District 5West Nippon Expressway Company Limited

Ms. Azusa Watase Mr. Evan Prado

Ms. Manabu YoshinagaMs. Shizu Yoshida

Fuji Engineering, Ergo VisionNEXCO-West Eng. Shikoku

for their cooperation and support for this project

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