Pre-XVIII CAVyT - Oto Hejmala

In-the-field Experience with Direct Enforcement Weigh-In-Motion Ing. Oto Hejmala

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Enforcement Systems – Discussion Topics » Drivers come up with new ways to avoid paying fines Enforcement system operators (together with vendors) must react Example – driving in shoulder lane or between lanes

» Problem of weighing at low speeds 5-20 km/h » Advanced camera system » Continuous monitoring of need for new calibration » Service partners 3 maintenance levels

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WIM System Accuracy Affected by various factors

Sensor parameters

Road quality

Vehicle behavior

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WIM System Accuracy – Sensors » Accuracy is a combination of sensor and road parameters » Typical parameters (today's standard) Longitudinal sensitivity (< ±2%) Linearity (< ±1 % of measurement range) Hysteresis (< 2 % of measurement range) Weighing accuracy (2 %) – in lab, for more see the road and vehicle influence

» Sensors must have additional parameters necessary for long-term functionality » Longitudinal sensitivity not constant » Sensor sensitivity not constant in time

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WIM System Accuracy â&#x20AC;&#x201C; Multiple Sensors

More measurements = lower uncertainty

Lower road age impact

Longer system lifespan

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WIM System Accuracy – Road Quality » Installation in a quality road required (COST 323, Version 3.0, August 1999) Low road deflection (high stiffness) No or minimal rutting (≤ 4 mm) Longitudinal slope < 1 % Transversal slope < 3 % Straight road section

» Parameters must be met during whole system operation lifetime

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WIM System Accuracy â&#x20AC;&#x201C; Road Quality

Longitudinal unevenness causes swaying (weight distribution shift)

Transversal unevenness (rutting) causes different sensor sensitivity

Dynamic road instability causes deflection (higher dynamic impact) 7

WIM System Accuracy – Vehicle Behavior » Drivers often try to avoid weighing Not all wheels fully on sensors Maneuvers (braking, acceleration, direction change etc.)

» Measurement validation to prevent higher weighing errors Checking the weight measurement process State which might cause a higher error marks the output as invalid

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Weighing in Whole Road Width

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Drivers avoid weighing by driving in the middle or on shoulder

Installing crash barriers can be unsafe

Solution by using additional sensors

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Weighing in Whole Road Width - Calibration » Driving between lanes or on shoulder may be affected by an error » Longitudinal slope causes measurement errors when wrongly calibrated

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α m/2+x%

m/2-x%

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Weighing Slowly Driving Vehicles

Drivers avoid weighing by driving slowly

A third row of sensors can be installed

Adding low-speed weighing sensors

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3D Scanning â&#x20AC;&#x201C; Vehicle Dimension Measurement

Using laser scanners

Highest possible scanning frequency for accurate measurements

Vehicle outline measurement

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3D Scanning â&#x20AC;&#x201C; Separating Closely Driving Vehicles

Vehicles drive too close behind one another

Difficult separation by inductive loops

Scanners to monitor separate vehicles

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3D Scanning â&#x20AC;&#x201C; Vehicle Classification

3D profile used to classify vehicles based on shape

Recognition of specific vehicle type

Cisterns, truck body types

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Discussion

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Road Quality – Recommendations » The road is the key part of the weighing system » Recommendation for existing road pavement Check the construction, rutting and deflection before installing sensors on roads where the WIM system should be installed WIM

» When designing a new road, it is necessary to consider: Road weakening caused by cuts for sensors (lower sensors = lower road quality requirements a longer lifespan) Future road wear and possible deflection change in time Temperature changes (and therefore deflection) so the road always meets COST 323 requirements The road must be of such quality to prevent long-term rutting above COST 323 requirements (≤ 4 mm)

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Road Quality – Choosing a Site » Correct approach – choosing site according to COST 323 Road radius, slope and expected lifespan are validated according to the project documentation Road evenness (rutting) and deflection is measured in the place of sensor installation and surrounding 200 m (COST 323 maximum limits: rutting 4 mm and deflection 150 μm) If the parameters do not comply, the road is reconstructed or a new site is chosen

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Road Quality – Choosing a Site » Example 1, Czech Republic (Q1 2019) Original road without reconstruction, remaining lifespan – 4 years, required warranty – 5 years Deflection in place of sensor installation – 225.5 μm, surrounding 200 m – 169 μm Conclusion: the supplier refused to install the system, road reconstruction or new site selection is in negotiation

» Example 2, Czech Republic (Q1 2019) Repaired road – new abrasive, bedding, base layers Deflection in place of sensor installation – 112.5 μm, surrounding 200 m – 139 μm Conclusion: the road is suitable, system will be installed

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Weighing in Whole Road Width

?

Drivers avoid weighing by driving in the middle or on shoulder

Installing crash barriers can be unsafe

Solution by using additional sensors

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Weighing in Whole Road Width - Calibration » Driving between lanes or on shoulder may be affected by an error » Longitudinal slope causes measurement errors when wrongly calibrated

m

α m/2+x%

m/2-x%

m

m/2+x%

m/2+x% 20

Weighing in Whole Road Width - Calibration METHOD A » Calibration not only inside lanes » But also in "virtual" lanes Between lanes On the shoulder

» Reliable detector necessary

METHOD B » Vehicle weighed by axle scales directly above sensors » The static weighing must be done in each lane separately » Problematic due to necessary traffic restrictions

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3D Scanning â&#x20AC;&#x201C; Inductive Loop Replacement

Reduction in intrusive road works and cabling simplification

Installation and maintenance cost reduction

Accurate detection of driving between lanes or shoulder 22

Speed Measurement of Weighed Vehicles » WIM measures speed (CZ certificate) Using existing system infrastructure inductive loops or wheel response This principle cannot be used for fining in RF

» New – 3/4D radar Can be used for vehicle behavior monitoring before and at the station – sudden braking, oblique driving, very slow driving etc.

Works in all weather conditions without need of high performance computers Certification in preparation in RF

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CAMEA Camera System Âť Overview cameras with wide field of view can document the whole weighing process from the front and rear Single image, sequence of images or video

Âť Documentation of vehicle behavior at the weighing site E.g. when driver claims to have braked or changed direction because of sudden road situation (obstacle, other vehicle, animal etc.)

To eliminate hidings, it is suitable to install cameras in all 4 corners of the station

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Lifted Axle Documentation

Drivers lift axles to reduce tire wear

And lower the axle when stopped to avoid fining

Solution by using a camera system

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Unique Customer Solutions www.cameatechnology.com Š 2020 CAMEA, spol. s r. o. All rights reserved. Specifications are subject to change.

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CAMEA WIM â&#x20AC;&#x201C; Bi-Directional, Free Flow Setup Overview camera

Portal

Scanners

Overview camera

Overview camera

ANPR cameras

Overview camera

3D radar

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