1. Bridge Research Group Dr Campbell Middleton Principal Investigator Dr Neil Hoult Research Associate Paul Fidler Research Associate Wireless Sensor Networks for Bridge Monitoring

2. Bridge Research Group Overview Monitoring OpportunitiesMonitoring Opportunities Wireless Sensor Networks (WSNs)Wireless Sensor Networks (WSNs) Field InstallationsField Installations  CUED  Humber Bridge

3. Bridge Research Group A Variety of Problems Steel BridgesSteel Bridges  corrosion, strain, displacement, bridge bashing Masonry Arch BridgesMasonry Arch Bridges  water ingress, material loss, displacement Reinforced Concrete BridgesReinforced Concrete Bridges  corrosion, strains, cracking

4. Bridge Research Group Steel Bridges The Humber Bridge One network has already been installed to measure the corrosion environment Future networks could include vibration and acoustic emission monitoring

5. Bridge Research Group RC Bridges – Monitoring Opportunities Half JointsHalf Joints  450 bridges  Difficult to inspect Hinge JointsHinge Joints  100 bridges Prestressed reinforcement conditionPrestressed reinforcement condition

6. Bridge Research Group RC Bridges – Monitoring Techniques Strains  Electrical resistance or MEMS vibrating wire gauges Corrosion  Acoustic Emissions (AE), but are there others? Inclination  Abutments & bearings Displacements  Across joints & cracks, bearings

7. Bridge Research Group Masonry Arch Bridges Monitoring possibilities  Digital imaging to measure displacements & loss of material  Sensors to measure water ingress into the joints  MEMS to measure pressure at the joints

8. Bridge Research Group Other Issues Bridge bashingBridge bashing Terrorist threatsTerrorist threats FireFire WeatherWeather  Snow or ice on the running surface

9. Bridge Research Group WSNs Networks composed of Sensors, Motes and GatewaysNetworks composed of Sensors, Motes and Gateways Motes take signal from sensor (typically analogue), process it and transmit itMotes take signal from sensor (typically analogue), process it and transmit it Gateways collect data from Motes and transmit it to the outside world (ADSL, GPRS, WiFi etc.)Gateways collect data from Motes and transmit it to the outside world (ADSL, GPRS, WiFi etc.)

10. Bridge Research Group Current WSNs Currently have a Crossbow network up and running in the Engineering Department System measures Temperature, Light, Sound, Acceleration and Magnetic Fields Data is acquired wirelessly from Motes in multiple rooms

11. Bridge Research Group Data Visualization A web interface to interrogate the Engineering NetworkA web interface to interrogate the Engineering Network Allows user to interrogate the data for multiple motes, sensors and date rangesAllows user to interrogate the data for multiple motes, sensors and date ranges Ultimately also have alerts and tie-in to analysis softwareUltimately also have alerts and tie-in to analysis software

12. Bridge Research Group Humber Bridge WSN Deployments

13. Bridge Research Group Anchorage Deployment - Success! (eventually) Network consists of 11 MICAzs (10 with MTS400 sensor boards) and a Stargate gatewayNetwork consists of 11 MICAzs (10 with MTS400 sensor boards) and a Stargate gateway The Stargate is connected to the Cambridge server via ADSLThe Stargate is connected to the Cambridge server via ADSL Data can be accessed in near real-time via a webpageData can be accessed in near real-time via a webpage

14. Bridge Research Group Anchorage Deployment - Monitoring Results Data shows good correlation with expected results System has already picked up an anomaly in operation (dehumidifier testing) Future developments may include tabulating maximum values and email alerts if thresholds are crossed

15. Bridge Research Group Anchorage Deployment – Problems Initial network formation problems due to wrong monitoring software & lengthy route update timesInitial network formation problems due to wrong monitoring software & lengthy route update times Radio transmission problems due to:Radio transmission problems due to:  Antenna quality  Spacing between wall and antenna  Fading Solution: external antennas with higher gain (5 dBm)Solution: external antennas with higher gain (5 dBm)

16. Bridge Research Group RC Bridge Monitoring Monitor inclination of bearings using inclinometersMonitor inclination of bearings using inclinometers Monitor crack movement using LPDTsMonitor crack movement using LPDTs Determine if there is long-term movementDetermine if there is long-term movement  Key Challenges: determining thresholds and actions Potential for expansion of the networkPotential for expansion of the network

17. Bridge Research Group Truly Remote Monitoring Proof of concept for completely remote system Data will be transmitted using GPRS (mobile phone) technology The gateway will be powered by a solar panel attached to the bridge

18. Bridge Research Group Acceleration Response of Hangers Vibration response may indicate damage  We need to be able to determine damping ratio with time Issues exist in terms of high data rate (power) and aerodynamic behaviour  Fortunately we can minimize power use by ‘windowing’ the data  Using MEMS sensors we can minimize the profile of the mote

19. Bridge Research Group RH / Corrosion / Moisture Sensing of Main Cables A number of potential techniques:  Acoustic Emission (AE), RH or electrical resistance AE is commonly used but requires high data rate processing & high power  We are working with Holroyd / Corus and colleagues from Imperial to develop a potential system Are the other techniques viable?

20. Bridge Research Group Can we cram it all in? Advantages of this project include staged deployment, projects of interest to everyone, various levels of complexityAdvantages of this project include staged deployment, projects of interest to everyone, various levels of complexity However implementing everything may be beyond the temporal and financial means of the projectHowever implementing everything may be beyond the temporal and financial means of the project Priorities?Priorities?