HI-TRAC® 100+

HIGH SPEED WEIGH-IN-MOTION DATA COLLECTION & PRE-SELECTION SYSTEM WITH ADVANCED LOOP PROFILING TECHNICAL MANUAL

HI-TRAC® is a registered Trade Mark of TDC Systems Limited

TDC Systems Limited Weston-Super-Mare ENGLAND Tel Fax Email Web : : : : +44 (0)1934 644299 +44 (0)1934 644255 sales@tdcsystems.co.uk www.tdcsystems.co.uk

TDC Systems Limited

HI-TRAC® 100+ Technical Manual

CONTENTS
1. System Overview 1.1. 1.2. Introduction Operating Principles 1.2.1. Weigh-in-Motion (WIM) 1.2.2. Automatic Counter/Classifying (AVC) Sensor Layout Options The In-Road Thermistor Advanced Features 1.5.1. Piezo Sensor Temperature Non-Linearity Compensation 1.5.2. Loop Profiling HI-TRAC 100+ Electronic Unit The Piezo Sensors The …ver más…

This function utilises an Advanced Vehicle Loop Signature Identification Algorithm to enhance vehicle classification accuracy.

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TDC Systems Limited

HI-TRAC® 100+ Technical Manual

1.2 1.2.1

Operating Principles Weigh-in-Motion (WIM)

The piezo-electric sensor outputs electrical charge proportional to the applied pressure of a vehicle axle passing over it. The electrical charge is converted into a voltage, by the HITRAC® 100+ electronic unit. The voltage signal is monitored by HI-TRAC® 100+ and used to determine axle detection times. The amplitude of the signal gives an indication of axle weight. With Piezo-Loop-Piezo sensor configuration, the piezoelectric sensors are installed a distance of 3 Metres apart in the road surface. The inductive loop is 2 Metres square. The loop is situated symmetrically between the sensors, in the lane. The time between the same axle being detected on both piezo sensors provides an axle speed measurement. The separation between each axle pair on the vehicle is calculated from the axle detection times recorded on a single sensor and multiplying by the calculated speed. For improved accuracy this result is averaged over the two sensors. The inductance value of the road-installed loop changes when a vehicle passes through the loop detection zone. This causes a change in the oscillation frequency of the loop detector circuitry inside the HI-TRAC® 100+ electronic unit. This change in