Federal Highway Administration Long‐Term Bridge Performance Program

LTBP UpdateforAASHTO Subcommittee on Bridge & Structures 2011

Scientific Quality Bridge Performance

Database

• Detailed inspection, periodic evaluation and monitoring (representative sample of bridges)

• Taking advantage of legacy data and existing research activities

Desired/Anticipated Outcomes

Improved knowledge of bridge performance

Development of improved predictive and deterioration models

Means to quantify effectiveness of various maintenance, preservation, repair and rehabilitation strategies

Tools for bridge management

Standards for testing and monitoring

LTBP Objective

Program Highlights to Date 

• Identification of key performance issues• Pilot bridge program• Inspection protocols• Data infrastructure & interface - LTBP Bridge Portal • Development of long term data collection phase• Outreach, communication & collaboration

Most Common Bridges in the US

Material / Type Number Cumulative 

Area

Million Sq. m.

Cumulative 

ADT

Millions VPDSimple Span Steel Stringer 103,836 469 704Continuous Steel Stringer 46,491 720 618Simple Span Concrete Slab 33,873 78 114Simple Span Concrete Stinger 9,988 51 44Simple Span Concrete T Beam 21,162 87 121Continuous Concrete Slab 31,565 132 190Continuous Concrete T Beam 6,247 53 102Simple Span Prestressed Concrete 

Stringer

51,731 637 655

Simple Span Prestressed Concrete 

Multiple Box Beam

38,103 122 181

Continuous Prestressed Concrete 

Stringer

13,560 205 146

Totals 356,556 2,554 2,875

Pilot Bridges

• I-15 over Cannery Road near Perry, UT

• Constructed in 1976• Single span AASHTO beams with

integral abutment• CIP concrete deck with asphalt

overlay and membrane• AADT of 22,250 with 29% truck traffic

• U.S Route 15 over I-66• Constructed in 1979• Continuous built-up steel

girder• CIP concrete deck• AADT of 16,500 with 6%

truck traffic

VA UT

Pilot Study PhasePilot Study Phase

Activity VA UT CA NJ NY MN FL

Bridge Selection Done Done Done Done Done Done Done

Finite Element Model Done Done Done Done Done Done Done

NDE Deck Survey Done Done Done Done Done Done Done

Visual Inspection Done Done Done Done Done Done Deck, Super. Done

Coring & Physical Testing Done Done Done Done Done Done Deck, Super. Done

Live Load Testing Done Done Done Done Done Done Done

Analysis of Results In Progress In Progress In

ProgressIn Progress

In Progress

In Progress In Progress

VA : Continuous steel stringerUT : Simple span pre-stressed concrete stringerCA : 2-span prestressed post-tensioned continuous CIP box girderNJ : Simple span steel stringerNY : Two simple spans of adjacent concrete box beamsMN : Steel deck trussFL: Precast, segmental post-tensioned concrete box beams

Pilot Study Phase Pilot Study Phase ––

Valuable Lessons LearnedValuable Lessons Learned

1. Coordination of activities with DOT2. Speed at which the desired amount & quality of data can be

collected, 3. Duration of traffic interruptions, 4. Ancillary costs – traffic control onsite power, etc.5. Data interpretation and integration & correlation of data from different

tests6. Coordination of field activities for deploying NDE technologies, and7. Costs of collecting data from a large number of bridges8. Protocols for technology verification and validation

Data Collection ParametersData Collection Parameters

• Maximum automation of data collection

• Speed • Scope and duration

of traffic interruption• Reasonable cost• Repeatability• Reliability

Electrical Resistivity

GPRImpact Echo

USW

Coring

LTBP Inspection & Testing Protocols

Data Infrastructure

LTBP Portal

• LTBP Portal is a web-based application• Security features (authentication, authorization)• Portal home page: data querying, data and image uploads, account

management• Provides a flexible and convenient filtering mechanism• Complex cross-data source querying (NBI, Pontis, Clarus and

Wunderground weather data, traffic and accident data, LTBP metadata, image and image metadata, LTBP experiment data)

• Multiple visualization options (table, map, histograms, etc)• Table: paged results, supports paging, sorting, and exporting large

data sets to Excel• Map: overlays bridge conditions and yearly traffic volume

GIS visualization of searched bridges

Size of circles encodes ADT

Color encodes deck condition of 2007

Blue squares indicate WIM stations

GIS visualization of searched bridges

Size of circles encodes ADT

Color encodes deck condition of 2007

Blue squares indicate WIM stations

Performance distribution of this cluster

Each bar indicates the number of bridges with a certain deck condition

The blue bar indicates the subgroup which contains Bridge I-15

Performance distribution of this cluster

Each bar indicates the number of bridges with a certain deck condition

The blue bar indicates the subgroup which contains Bridge I-15

Map shows the location of those 3 bridges that have deck condition 9

Map shows the location of those 3 bridges that have deck condition 9

What is the expected condition in 5 years?

The substructure condition is predicted to decrease to 7 whereas to deck condition is most likely to stay at 7

What is the expected condition in 5 years?

The substructure condition is predicted to decrease to 7 whereas to deck condition is most likely to stay at 7

How fast did the deterioration process compared to similar bridges?

How fast did the deterioration process compared to similar bridges?

Bridge Portal Rollout

Long Term Data Collection PhaseLong Term Data Collection Phase

• Begin 2012• Reference Bridges • Cluster Bridges• Scale & Scope of activities will depend heavily on future

resources

Reference Bridge – Data Collection 

Visual InspectionNon‐standardArms lengthSegmentalConventional Tools

Mat’l TestingMaterial SamplingStiffnessStrengthPorosity

Chloride Content

Global TestingLoad Testing Modal TestingContinuous 

Monitoring

NDEImpact EchoGPRUltrasonicSeismicResistivity

Approximat e Scale: 200 ft

Reference Bridge and Supporting Cluster

Visual Visual InspectionInspectionNon‐standardArms lengthSegmentalConventional Tools

Comparison: Reference vs. ClusterComparison: Reference vs. ClusterIdentify discrepancies –

establish root 

causesEstablish typical levels of variability

Reference Bridge Cluster bridges

Approximat e Scale: 30 mi

Multiple Clusters of Similar Bridges

Cluster of Bridge 

Type A

Approximate Scale: 3000

mi

Comparison: Cluster vs. ClusterComparison: Cluster vs. ClusterIdentify influences of climate, traffic, 

maintenance practices, etc. 

Outreach, Communication & CollaborationOutreach, Communication & Collaboration

• TRB Advisory Board• LTBP State Coordinators • T-9• T-18• TSP2 Bridge Preservation Partnerships• TRB committees