Wireless Sensor Networks for Bridge Monitoring

Bridge Research GroupBridge Research Group

Paul FidlerPaul FidlerResearch AssociateResearch Associate

Dr Neil HoultDr Neil HoultResearch AssociateResearch Associate

Dr Campbell MiddletonDr Campbell MiddletonPrincipal InvestigatorPrincipal Investigator

Wireless Sensor NetworksWireless Sensor Networksfor Bridge Monitoringfor Bridge Monitoring


OverviewOverview

• Monitoring Monitoring OpportunitiesOpportunities

• Wireless Sensor Wireless Sensor Networks (WSNs)Networks (WSNs)

• Field InstallationsField InstallationsCUEDCUEDHumber BridgeHumber Bridge


A Variety of ProblemsA Variety of Problems

• Steel BridgesSteel Bridges corrosion, strain, corrosion, strain, displacement, bridge displacement, bridge bashingbashing

• Masonry Arch BridgesMasonry Arch Bridges water ingress, material water ingress, material loss, displacementloss, displacement

• Reinforced Concrete Reinforced Concrete BridgesBridges corrosion, strains, corrosion, strains, crackingcracking


Steel BridgesSteel Bridges

• The Humber BridgeThe Humber Bridge• One network has One network has

already been installed already been installed to measure the to measure the corrosion environmentcorrosion environment

• Future networks could Future networks could include vibration and include vibration and acoustic emission acoustic emission monitoring monitoring


RC Bridges – RC Bridges – Monitoring OpportunitiesMonitoring Opportunities

• Half JointsHalf Joints450 bridges450 bridgesDifficult to inspectDifficult to inspect

• Hinge JointsHinge Joints100 bridges100 bridges

• Prestressed Prestressed reinforcement reinforcement conditioncondition


RC Bridges – RC Bridges – Monitoring TechniquesMonitoring Techniques

• StrainsStrainsElectrical resistance or Electrical resistance or MEMS vibrating wire MEMS vibrating wire gaugesgauges

• CorrosionCorrosionAcoustic Emissions (AE), Acoustic Emissions (AE), but are there others?but are there others?

• InclinationInclinationAbutments & bearingsAbutments & bearings

• DisplacementsDisplacementsAcross joints & cracks, Across joints & cracks, bearingsbearings


Masonry Arch BridgesMasonry Arch Bridges

• Monitoring Monitoring possibilitiespossibilitiesDigital imaging to Digital imaging to measure displacements measure displacements & loss of material& loss of materialSensors to measure Sensors to measure water ingress into the water ingress into the jointsjointsMEMS to measure MEMS to measure pressure at the jointspressure at the joints


Other IssuesOther Issues

• Bridge bashingBridge bashing• Terrorist threatsTerrorist threats• FireFire• WeatherWeather

Snow or ice on the Snow or ice on the running surfacerunning surface


WSNsWSNs• Networks composed Networks composed

of Sensors, Motes of Sensors, Motes and Gatewaysand Gateways

• Motes take signal Motes take signal from sensor from sensor (typically analogue), (typically analogue), process it and process it and transmit ittransmit it

• Gateways collect Gateways collect data from Motes and data from Motes and transmit it to the transmit it to the outside world (ADSL, outside world (ADSL, GPRS, WiFi etc.)GPRS, WiFi etc.)


Current WSNsCurrent WSNs• Currently have a Currently have a

Crossbow network up Crossbow network up and running in the and running in the Engineering Engineering DepartmentDepartment

• System measures System measures Temperature, Light, Temperature, Light, Sound, Acceleration Sound, Acceleration and Magnetic Fieldsand Magnetic Fields

• Data is acquired Data is acquired wirelessly from Motes in wirelessly from Motes in multiple roomsmultiple rooms


Data VisualizationData Visualization

• A web interface to A web interface to interrogate the interrogate the Engineering NetworkEngineering Network

• Allows user to Allows user to interrogate the data interrogate the data for multiple motes, for multiple motes, sensors and date sensors and date rangesranges

• Ultimately also have Ultimately also have alerts and tie-in to alerts and tie-in to analysis softwareanalysis software


Humber Bridge Humber Bridge WSN DeploymentsWSN Deployments


Anchorage DeploymentAnchorage Deployment- Success! (eventually)- Success! (eventually)

• Network consists of Network consists of 11 MICAzs (10 with 11 MICAzs (10 with MTS400 sensor MTS400 sensor boards) and a boards) and a Stargate gatewayStargate gateway

• The Stargate is The Stargate is connected to the connected to the Cambridge server via Cambridge server via ADSLADSL

• Data can be Data can be accessed in near accessed in near real-time via a real-time via a webpagewebpage


Anchorage Deployment Anchorage Deployment - Monitoring Results- Monitoring Results

• Data shows good Data shows good correlation with correlation with expected resultsexpected results

• System has already System has already picked up an anomaly picked up an anomaly in operation in operation (dehumidifier testing)(dehumidifier testing)

• Future developments Future developments may include tabulating may include tabulating maximum values and maximum values and email alerts if email alerts if thresholds are crossedthresholds are crossed

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Mote 2 Mote 8Mote 7Mote 4

Mote 3


Anchorage Deployment – Anchorage Deployment – ProblemsProblems

• Initial network formation Initial network formation problems due to wrong problems due to wrong monitoring software & monitoring software & lengthy route update lengthy route update timestimes

• Radio transmission Radio transmission problems due to:problems due to:Antenna qualityAntenna qualitySpacing between wall and Spacing between wall and antennaantennaFadingFading

• Solution: external Solution: external antennas with higher antennas with higher gain (5 dBm)gain (5 dBm)


RC Bridge MonitoringRC Bridge Monitoring• Monitor inclination of Monitor inclination of

bearings using bearings using inclinometersinclinometers

• Monitor crack Monitor crack movement using movement using LPDTsLPDTs

• Determine if there is Determine if there is long-term movementlong-term movementKey Challenges: Key Challenges: determining thresholds determining thresholds and actionsand actions

• Potential for expansion Potential for expansion of the networkof the network


Truly Remote MonitoringTruly Remote Monitoring• Proof of concept for Proof of concept for

completely remote completely remote systemsystem

• Data will be Data will be transmitted using transmitted using GPRS (mobile GPRS (mobile phone) technologyphone) technology

• The gateway will be The gateway will be powered by a solar powered by a solar panel attached to panel attached to the bridgethe bridge


Acceleration Response of Acceleration Response of HangersHangers

• Vibration response may Vibration response may indicate damageindicate damageWe need to be able to We need to be able to determine damping ratio with determine damping ratio with timetime

• Issues exist in terms of Issues exist in terms of high data rate (power) high data rate (power) and aerodynamic and aerodynamic behaviourbehaviourFortunately we can minimize Fortunately we can minimize power use by ‘windowing’ the power use by ‘windowing’ the datadataUsing MEMS sensors we can Using MEMS sensors we can minimize the profile of the minimize the profile of the motemote


RH / Corrosion / Moisture Sensing RH / Corrosion / Moisture Sensing of Main Cablesof Main Cables

• A number of potential A number of potential techniques:techniques:Acoustic Emission (AE), RH Acoustic Emission (AE), RH or electrical resistanceor electrical resistance

• AE is commonly used AE is commonly used but requires high data but requires high data rate processing & high rate processing & high powerpowerWe are working with We are working with Holroyd / Corus and Holroyd / Corus and colleagues from Imperial to colleagues from Imperial to develop a potential systemdevelop a potential system

• Are the other techniques Are the other techniques viable?viable?


Can we cram it all in?Can we cram it all in?• Advantages of this Advantages of this

project include staged project include staged deployment, projects of deployment, projects of interest to everyone, interest to everyone, various levels of various levels of complexitycomplexity

• However implementing However implementing everything may be everything may be beyond the temporal beyond the temporal and financial means of and financial means of the projectthe project

• Priorities?Priorities?

Documents

Wireless Sensor Networks for Bridge Monitoring