Weigh-in-Motion (WIM)
Weigh In Motion Enforcement (WIM-E)
The checking of overloaded HGVs using calibrated scales as well as in conjunction with 
WIM-P systems entails interfering with the flow of traffic and is also very costly in terms of time and personnel. The stated objective of Traffic Data Systems was to develop, in conjunction with a competent partner, a fully automatic process for continuously checking and registering overloaded vehicles (WIM-E) which required no subsequent manual weighing.
Project partner, Robot Visual Systems, and Traffic Data Systems installed a WIM-E system in the Czech Republic (to the south of Prague) in December 2007. The system is intended to monitor compliance with the ban on heavy goods traffic and, in the event of an infringement, to provide evidence for retribution.
The world's first WIM system with calibration facility was approved by the Czech Meteorological Institute (CMI) in Brno on 15th August 2008. Since then, an average of 500 overload infringements above the limit of the permissible gross weight of 12t has been recorded each month. One of the outstanding advantages of this system is that it checks the traffic 24 hours a day and 365 days a year so that continuous monitoring is possible.
A condition for approval by the national approval authorities was evidence of the accuracy and a description of the process for determining the weight. The national requirements for image and video data relating to the vehicle and driver also had to be documented.
TDS 821R/WIM-E
The TDS 821R/WIM-E system is equipped with 2 or 3 rows of sensors and one double inductive loop per lane. The vehicle, driver and correct traversal are documented by means of an IR photographic camera and an IR sequence camera.
As well as the gross weight, the TDS 821R/WIM-E also calculates the weights of wheels, axles and axle groups which are also subject to weight limitations as part of the vehicle weighing process.
Examples of hardware and software expansions include:
- Robot IR photographic and IR sequence camera
- Robot ANPR camera (Automatic Number Plate Recognition)
- Hardware and software for image and data transmission
Sensors
LINEAS quartz sensors from Kistler Instrumente AG , which are available in lengths of 150 cm, 175 cm and 200 cm, are used for measuring weight. This enables rows of sensors to be arranged in any widths. Interference with the carriageway is minimal, as the installation depth is only 55 mm and the width of the slot only 72 mm.
The high-impedance signals of the LINEAS quartz sensors are converted into low-impedance output signals by a multi-channel charge amplifier, and subsequently digitalised by means of an A/D converter.
Signal processing
Wheel, axle and axle group loads (double and triple axles) as well as the gross vehicle weight are calculated from the data. The time stamp for the data has a resolution of 10 ms. Classification by axle silhouette and total weight is carried out in accordance with TLS 2002, FG2, and the European COST 323 directives (European WIM Specification produced by the COST 323 Management Committee). External devices are monitored and controlled by means of function group FG6.
Software for a central unit is available for the automatic interrogation of data in an extensive network of traffic and axle load monitoring systems.
The traversal of each vehicle is documented by the sequence camera. If no overload is detected, these data are irrevocably deleted. If an overload condition is reliably detected, the sequence is stored and in addition a photograph is taken of the vehicle.This photo with superimposed data (date, time, weight etc.) enables the vehicle and driver to be identified. In parallel, the integral ANPR camera reads the number plate.
The data are encrypted on the Robot system and transmitted to a central unit where the data are checked by an operator.
Technical data
- Up to 8 double loops with superimposed frequencies
- Optimised for TLS loop type 2
- BASt certification, accuracy class A1 with 300 m cable length
- Up to 6-lane WIM each with 2 rows of sensors
- Optimised for LINEAS sensors from Kistler Instrumente AG
- ARM processor
- Integral quad-band GPRS/EDGE modem (UMTS optional)
- Card holder for 3V SIM cards
- Control module with integral FG1, FG2 and FG6
- RS 485 interface (local bus)
- RS 232 interface (modem)
- Up to 32GB Mini SD card
- RTC incl. leap year, 24 h, min, s, 0.01 s
- 28-channel A/D converter 100 kS/s
- 16 digital inputs/outputs
- USB host
- Ethernet interface
- Temperature range –25°C/+75°C
- 19-inch rack or desktop case
- Power supply 230V/50-60 Hz or 12-28VDC
(Technical data are subject to change without notice)
