Transcript Slide 1

WEIGH-IN-MOTION SYSTEM
CALIBRATION
CURRENT CHALLENGES
Significant Growth in CMV Traffic
• Increased congestion and delay
• Demand for larger and heavier vehicles
• Mounting stress on infrastructure
• Greater need for effective and efficient enforcement
CURRENT CHALLENGES
Traditional WIM System Calibration Method Limitations
• Field calibration procedures
– Costly to perform
– Occur infrequently
• Auto-calibration procedures
– May lead to progressive drift
• Multiple weight sensor installation
– Costly
– Provides modest gains in accuracy
• Post-collection data editing
– provides only general indication of data conformance to expected
weight distributions
– not timely in flagging WIM performance problems
BACKGROUND
2006 European Scan Tour
• Emerging technologies
• Unconventional procedures
• Novel data
applications
• Innovative funding
mechanisms
• Multinational
harmonization
THE NETHERLANDS
BELGIUM
GERMANY
FRANCE
SWITZERLAND
SLOVENIA
EUROPEAN APPROACH
WIM System Calibration
• Continuous calibration
– France, The Netherlands, during scheduled enforcement
• Quality assurance
– The Netherlands issues QA Statement with every data request
• Dynamic calibration
– The Netherlands
utilizes specially
designed vehicle
SUPPORTING TECHNOLOGIES
• Overheight Vehicle Detection System
• Vehicle Profiler System
• WIM Systems
– In-road
– Bridge
• Dynamic Calibration Vehicle
• Vehicle Identification System
• Advanced Routing/Permitting System
• Archived Records Database
SUPPORTING TECHNOLOGIES
In-road WIM System
Functions
• Measures and records axle, gross weight using
piezo quartz, piezo ceramic, fiber optic sensors
• Provides 24/7 monitoring
Considerations
• May be less accurate than traditional WIM systems
• Low cost supports wider implementation
• $9,000 - $32,500 per lane
Estimated Cost
• Varies by sensor type, on-site communication requirements
• Requires additional, ongoing maintenance with associated
costs
SUPPORTING TECHNOLOGIES
Bridge WIM System
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•
Considerations
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•
Estimated Cost
Requires suitable bridge and location
Most successful on short, stiff bridges
Structural assessments require transducer calibration
Calibration may require specialized expertise
• $100,000 - $130,000 per bridge/system
• Varies by sensor type, on-site communication requirements
1,0
0,5
0,0
-0,5
Strain (V)
Functions
• Measures, records weight using existing structures
instrumented with strain transducers/gauges
• Measures, records axles using traditional sensors or
Nothing-on-Road/Free-of-Axle Detector (NORFAD) systems
-1,0
-1,5
-2,0
-2,5
-3,0
Static
-3,5
Dynamic
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0,5
1
1,5
Time (s)
2
2,5
3
SUPPORTING TECHNOLOGIES
Vehicle Identification System
• Cameras capture vehicle silhouette, license plate images
Functions
Considerations
Estimated Cost
• OCR software converts license plate image to numeric data
• Images/data transmitted via DSRC to portable computer
used by enforcement officials
• Conversion of license plate images may result in errors
• $52,000 - $80,000 per system
• Varies by camera type, on-site communication requirements
SUPPORTING TECHNOLOGIES
Archived Records Database
• Supports data-driven enforcement scheduling
Functions
• Supports preventative carrier contacts
• Supports enhanced data quality
• Encourages long-term performance monitoring
Considerations
• Requires procedures for quality control
Estimated Cost
• $225,000 - $300,000
SUPPORTING TECHNOLOGIES
Dynamic Calibration Vehicle
Functions
• Calibrates dynamic load measurements
to true dynamic - rather than static - loads
Considerations
• May be used to calibrate traditional
static weigh bridges
Estimated Cost
• $1.72 million for vehicle construction
• $6,300 per in-service day
IMPLEMENTATION
CONTINUOUS
CALIBRATION
Dynamic Calibration
Vehicle
Archived Records
Database
Vehicle Identification
System
Bridge WIM System
AND/OR
In-road WIM System
Database
Camera/OCR
DSRC
Voltage/Axle Sensors
(X Weight Accuracy)
Computer
Interface/Software
Weight/Axle Sensors
(X Weight Accuracy)
Computer
Interface/Software
IMPLEMENTATION
CONTINUOUS
CALIBRATION
QUALITY
ASSURANCE
Database
Database
Camera/OCR
Camera/OCR
DSRC
DSRC
Voltage/Axle Sensors
(X Weight Accuracy)
Voltage/Axle Sensors
(X Weight Accuracy)
Computer
Interface/Software
Computer
Interface/Software
Weight/Axle Sensors
(X Weight Accuracy)
Weight/Axle Sensors
(X Weight Accuracy)
Computer
Interface/Software
Computer
Interface/Software
Dynamic Calibration
Vehicle
Archived Records
Database
Vehicle Identification
System
Bridge WIM System
AND/OR
In-road WIM System
IMPLEMENTATION
CONTINUOUS
CALIBRATION
QUALITY
ASSURANCE
Dynamic Calibration
Vehicle
Archived Records
Database
Vehicle Identification
System
Bridge WIM System
AND/OR
In-road WIM System
DYNAMIC
CALIBRATION
Dynamic Calibration
Vehicle
Database
Database
Camera/OCR
Camera/OCR
DSRC
DSRC
Voltage/Axle Sensors
(X Weight Accuracy)
Voltage/Axle Sensors
(X Weight Accuracy)
Voltage/Axle Sensors
(X Weight Accuracy)
Computer
Interface/Software
Computer
Interface/Software
Computer
Interface/Software
Weight/Axle Sensors
(X Weight Accuracy)
Weight/Axle Sensors
(X Weight Accuracy)
Weight/Axle Sensors
(X Weight Accuracy)
Computer
Interface/Software
Computer
Interface/Software
Computer
Interface/Software
BENEFITS
• Eliminates need for resource-intensive
manual field calibration
• Enhanced weight data quality benefits broader
transportation and enforcement agency activities
– Planning and programming
– Enforcement
– Design and engineering
FUNCTIONAL INTERFACE

QUESTIONS