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 SLOVENIA SWITZERLAND

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 Considerations Provides 24/7 monitoring May be less accurate than traditional WIM systems Low cost supports wider implementation Estimated Cost $9,000 - $32,500 per lane Varies by sensor type, on-site communication requirements Requires additional, ongoing maintenance with associated costs

SUPPORTING TECHNOLOGIES Bridge WIM System 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 Considerations Requires suitable bridge and location Most successful on short, stiff bridges Structural assessments require transducer calibration Calibration may require specialized expertise Estimated Cost $100,000 - $130,000 per bridge/system Varies by sensor type, on-site communication requirements

SUPPORTING TECHNOLOGIES Vehicle Identification System Functions Cameras capture vehicle silhouette, license plate images OCR software converts license plate image to numeric data Images/data transmitted via DSRC to portable computer used by enforcement officials Considerations Conversion of license plate images may result in errors Estimated Cost $52,000 - $80,000 per system Varies by camera type, on-site communication requirements

SUPPORTING TECHNOLOGIES Archived Records Database Functions Supports data-driven enforcement scheduling 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 In-road WIM System AND/OR DSRC Camera/OCR Database Computer Interface/Software Weight/Axle Sensors (X Weight Accuracy) Computer Interface/Software Voltage/Axle Sensors (X Weight Accuracy)

IMPLEMENTATION CONTINUOUS CALIBRATION QUALITY ASSURANCE Dynamic Calibration Vehicle Archived Records Database Vehicle Identification System Bridge WIM System In-road WIM System AND/OR Database DSRC Camera/OCR Database DSRC Camera/OCR Computer Interface/Software Weight/Axle Sensors (X Weight Accuracy) Computer Interface/Software Weight/Axle Sensors (X Weight Accuracy) Computer Interface/Software Voltage/Axle Sensors (X Weight Accuracy) Computer Interface/Software Voltage/Axle Sensors (X Weight Accuracy)

IMPLEMENTATION CONTINUOUS CALIBRATION QUALITY ASSURANCE DYNAMIC CALIBRATION Dynamic Calibration Vehicle Archived Records Database Vehicle Identification System Bridge WIM System In-road WIM System AND/OR Database DSRC Camera/OCR Database DSRC Camera/OCR Computer Interface/Software Weight/Axle Sensors (X Weight Accuracy) Computer Interface/Software Weight/Axle Sensors (X Weight Accuracy) Computer Interface/Software Weight/Axle Sensors (X Weight Accuracy) Computer Interface/Software Voltage/Axle Sensors (X Weight Accuracy) Computer Interface/Software Voltage/Axle Sensors (X Weight Accuracy) Dynamic Calibration Vehicle Computer Interface/Software Voltage/Axle Sensors (X Weight Accuracy)

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