Monitoring for Bridge Scour Phase 3 Installation PennDOT Technical Advisor:
Paul Koza
Principal Investigator:
Dr. Ervin Sejdic
Graduate Students:
Nicholas Franconi Michael Rothfuss 1
Introduction Requirements
Design Installation Discussion Conclusion
2003 – Montezuma Creek Utah
2009 – Malahide Dublin
What is Bridge Scour?
2015 – I-10 California 2
Introduction Requirements
Design Installation Discussion Conclusion
Scour Code Description 8 ‐ Bridge foundations determined to be stable for the assessed or calculated scour condition. 6 ‐ Scour calculation or evaluation has not been made 5 - Bridge foundations determined to be stable for assessed conditions 4 - Bridge foundations determined to be stable for assessed scour conditions but field review indicates action is required 3 to 0 ‐ Bridge is scour critical; bridge foundations determined to be unstable U ‐ Bridge with unknown foundation that has not been evaluated for scour.
The National Bridge Inspection Standards require highway bridge inspections every 24 months
A bridge is classified as “structurally deficient” and in need of repair if the rating for a key structural elements is 4 or below
Bridge Scour Assessment
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In the United States… Over 200 million trips are taken daily across structurally deficient and functionally obsolete bridges in the 102 largest metropolitan U.S. regions. Introduction Requirements
Design Installation
As of 2015, Pennsylvania has the 4,783 structurally deficient bridges
In 2013, the American Society of Civil Engineers assigned a grade of C+ to the Nation’s bridges
While conditions of bridges have steadily improved, the 2015 National Bridge Inventory reported: 58,000 structurally deficient bridges 84,000 functionally obsolete bridges
Discussion Conclusion
The FWHA estimates that to eliminate the bridge backlog by 2028, an investment of $20.5 billion would be required annually.
Bridge Scour Statistics
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Introduction Tilt Sensor
Requirements
Design
Electrical Conductivity
Installation Discussion Conclusion
Sonar Scour Monitor
Example data from Sonar Mapping
Techniques for Monitoring Scour
Float-out Device
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Introduction Requirements
Design Installation Discussion Conclusion
Techniques for Monitoring Scour
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Introduction Requirements
Design
Requirements
Installation Discussion Conclusion
• Goals Mechanical and electrical float-out specifications Lifetime and indicators for RF receiver
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PennDOT Requirements
Introduction Requirements
Design Installation Discussion Conclusion
RF Receiver Low Power Continuously Operating Custom Light Indicator Durable Enclosure
Float-Out Device Tilt Sensitive Activation Conforms to FCC Regulation External Magnetic Switch Unique Serial Number
Float-out and Receiver Requirements
8
Introduction Requirements
Design
Design
Installation Discussion Conclusion
• Goals Overview of float-out electronics Float-out collision avoidance, and construction durability testing Overview of receiver electronics Receiver electronics validation
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Receiver PCB
RF Receiver with Off-Grid Power
Charge Controller
Introduction Requirements
Design Installation
Software Architecture
Discussion Conclusion
Power Consumption Calculations
RF Receiver Design
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Introduction
• Key Float-out Improvements Passive Reset Switch Extended 20 Year lifetime Automated false trigger reset No external reset switch
Power Enable and Reset Circuitry
Requirements
Design
Float-out Device Hardware Architecture
Installation
Voltage Regulator
Discussion
Power Enable
Conclusion
RF Microcontroller Power Amplifier
Passive Tilt Sensitive Switch
Antenna
Float-out Device Design
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• Collision Avoidance Algorithm Custom ALOHA NET Algorithm Transmit Period (T) of 2.5 milliseconds Pseudo-Random seeded from Serial Number Introduction
PseudoRandom Number Generation Transmit Scour Data Packet
Requirements
Design
Bridge ID #
Installation
Wait Predetermined Period of Time
Scour Data Packet Serial # Scour Loc.
Scour Depth
Possible Float-out Devices = 216 = 65536 devices
Discussion Conclusion
• Complies with FCC Regulation Maximum Transmit Power - 16.47 dBm Power Spectral Density - 6.72 dBm/3 kHz 6 dB Bandwidth - 513.25 kHz
Testing of the Float-out Devices
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Float-Out Devices Painted and Labeled for Installation
Introduction Requirements
Design Installation Discussion Conclusion
• Float-Out Testing Procedure Reset RF Receiver Removal of magnet to activate ARM State Tilt Float-out 90 degrees to activate ON State Verify scour indication Re-secure magnet
Final Testing Procedures
13
Introduction Requirements
Design
Installation
Installation Discussion Conclusion
• Goals Receiver Installation Float-out Device Installation
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Introduction Requirements
• PennDOT Selected Bridge Covers Pine Creek Scour present at bridge Armstrong County SR 1028 Segment 240 Bridge ID #: 03102802400395
Design Installation Discussion Conclusion
• Scour location Selection Process Location 1 – Significant scour present Location 2 – Significant scour present Location 3 – Scour expected to occur Location 4 – No expected scour
Bridge Location Information
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Introduction
Due to the age of the bridge (1923), limited documentation is available, specifically relating to the supporting structures.
Requirements
Design Installation Discussion Conclusion
Bridge Documentation
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L.G. Hetager Drilling was contracted to perform the installation in November, 2015.
Introduction Requirements
Design Installation Discussion Conclusion
Gardner Denver articulated drill rig track mount.
Articulating rig with geotechnical mast, tooling, and platform extending over the bridge
Float-out Device Flush Casing Drill Rig
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Float-out Installation 1. Prepare backfill 2. Drill to 8 foot depth 3. Lift drill by 8 inches 4. Test Float-out Device 5. Lower Float-out Device 6. Hold in position with Tamper 7. Backfill appropriate quantity 8. Repeat Steps 3-7 until completed
Introduction Requirements
Design Installation Discussion Conclusion
Float-out Installation Jig
In slow water, float-out devices remained under the bridge, however in flood conditions, the capsule should be carried downstream.
Installed Float-out Device Locations
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Introduction Requirements
Design Installation Discussion Conclusion
Backfill Calculations
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Introduction Requirements
Design Installation Discussion Conclusion
Antenna Orientation and Receiver Installation
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Introduction
Antenna Selection Directional Patch Antenna Trade-offs Facing downstream for Maximum Coverage Successful communication to tree line (~500 ft.) Unable to receive signal from upstream installation location due to antenna orientation
Requirements
Design Installation Discussion Conclusion
Distance Testing of float-out device and Antenna Orientation
Antenna Orientation and Receiver Installation
LEDs visible in daylight after button press
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Significant debris downstream cause the float-out device to be trapped in slower moving water
Introduction Requirements
Design Installation Discussion Conclusion
Antenna Orientation and Receiver Installation
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Introduction Requirements
Design Installation Discussion Conclusion
The proposed scour configuration requires a total drilled depth of 8 feet. The drill time for Location 1, Location 2, and Location 4 was approximately 45 minutes. Location 3 took approximately 90 minutes to drill, due to a boulder The installation of each individual float-out device took approximately 15 minutes.
The use of multi-depth float-out devices is impractical for monitoring purposes Float-out devices will outlast the RF receiver solar panel and battery backup system The float-out capsules in quantity will cost under < $100/device in parts Due to solar panel and battery, receiver is significantly more expensive ~$2,000
Float-out Installation Discussion
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• Conceptual Map of Scour Database Bridges monitored remotely Not limited to float-out monitoring Big data processing to aide in detection Event Prediction Introduction Requirements
Design Installation
Birmingham Bridge
Location 4 Start Scour Depth: 1 foot GPS Latitude: 40.434176 GPS Longitude: -79.973581
Location 1 Location 2 Location 3 Location 4
Discussion Conclusion
Location 4 – Level 3 Serial Number: 0x0000 Depth Indicator: Orange Scour Depth: 8 Feet GPS Latitude: 40.434176 GPS Longitude: -79.973581 Installation Date: 09/27/2015 Release Date: 09/27/2015 Additional Bridges: Bridge 1 / Time 1 Additional Bridges: Bridge 2 / Time 2
IoT Implementation of Bridge Monitoring
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Introduction Requirements
Design
Conclusion
Installation Discussion Conclusion
• Goals Low Cost solution for monitoring scour Low maintenance Solution Designed for shallow water ways and rural bridges Improvements to the system can be made by reducing lifetime
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Introduction Requirements
Design Installation
Questions?
Discussion Conclusion
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