Weigh In Motion (WIM)

Last change: 09.12.2018

OIML R134-1 certified Weigh-In-Motion System WIM-DSP 32

The main focus in the dynamic weighing (Weigh-In-Motion) of vehicles is on the safety of road users, compliance with legal regulations and also the protection and long-term maintenance of the traffic infrastructure. Individual items of vehicle data are recorded using axle load sensors and inductive loops installed in the road surface. These items of data include wheel weights, axle weights, axle group weights and overall weights of heavy vehicles.

The WIM-DSP 32 system with PSHC (Piezo Sensor Health Care) was introduced in spring 2016 and has been certified by METAS according to the OIML R134-1 standard between Mai and August 2016. Traffic Data Systems is the world’s first and only manufacturer capable of providing an OIML-R134-1 certified low-speed and high-speed Weigh-In-Motion system with only 3 rows of OIML-certified Lineas sensors for a speed range of 5 km/h to 120 km/h for heavy goods vehicles and for 5 km/h to 140 km/h for light goods vehicles (temperature range: -30°C/+75°C with a relative humidity of up to 85%).

Accuracies of ±5% (initial verification) and ±10% (in-service inspection) respectively in accordance with OIML R134 have been achieved. Traffic Data Systems points out that although these results appear at first glance to be less accurate than those of most competitors, these have not been tested in accordance with OIML R134, and certainly not in the speed range between 5 km/h and 140 km/h.

For customers, the OIML certificate is a sign of quality at the highest level. Traffic Data Systems has already obtained type approvals for Switzerland (CH-W7-17844-00) and Latvia (987/2017). Only documents of this kind are accepted by local government authorities for calibrating WIM systems before they can be used for enforcement or tolling.

WIM-DSP 32 is the first Weigh-In-Motion system that has long-term sensor monitoring (PSHC). It has been developed for use with Kistler Lineas sensors and Kistler charge amplifiers. The new design has an integral colour graphics display and touch keys for easy configuration and functional control.

The WIM-DSP 32 enables a broad range of applications to be realised – starting from simple WIM systems for statistical purposes to sophisticated WIM-E (Weigh in Motion Enforcement) and WIM-T (Tolling) systems with monitoring and control of lane changes.

The lead-sealable aluminium housing of the WIM-DSP 32 and the connecting cables to the Kistler charge amplifiers comply with protection class IP67 (EN60529). With these features, the WIM-DSP 32 in conjunction with the TMCS-U Remote Monitoring Station sets new standards in the Weigh in Motion systems market.

The TMCS-U is a complete TLS remote monitoring station with control module, integral function groups FG1, FG2, FG3 and FG6, integral UPS, 3G/UMTS modem and 16 inductive loop detectors/classifiers. The data and power supply cables between WIM-DSP 32 and TMCS-U and the inductive loop connections can be up to 300 m long. WIM-DSP 32 and TMCS-U have a high integration density with outstanding performance features and low power consumption. The TMCS-U and WIM-DSP 32 assemblies ensure precise time synchronisation with optional data signature.

The WIM-DSP 32 also helps to greatly simplify the installation and operation of WIM systems. The reduced number of cable connections and terminations alone makes a major contribution to the reliability and performance of the overall system.

Weigh-In-Motion Enforcement and Tolling (WIM-E and WIM-T)

Traffic Data Systems was the first company to develop WIM Enforcement Systems, and is therefore the initiator of this technology. Unlike conventional WIM applications (Statistics and Preselection), the focus in WIM-E is on the dynamic weighing of vehicles with simultaneous photographic recording of the vehicle and the legally usable documentation of the 'incident' if overloading is detected. In case of tolling applications the system supplies the individual vehicle weights, which are needed  to caluculate the weight based tolling fees.

Three rows of Lineas sensors are required for Weigh in Motion Enforcement/Tolling systems in order to satisfy a higher accuracy class in accordance with OIML R134-1. With enforcement/tolling systems, the sensor installed at an angle at the end of the sensor field is required for providing evidence of the position of the vehicle in the lane and to detect single or twin tyres.

Weigh in Motion Enforcement (WIM-E) also requires an RWIS station (details on request) in order to suspend measurements in weather conditions /situations with impacted snow covering, slush or icy roads.

In addition, ANPR and overview cameras are required to document correct traversals and the number of rolling and raised axles, and to automatically filter out overloaded vehicles for checks.

Weigh In Motion Preselection (WIM-P)

Systems that allow monitoring to be carried out by the authorities have safety in mind. The measures undertaken by the police traffic monitoring unit or the Bundesamt für Güterverkehr (BAG - Federal Office for Goods Traffic) include the specific checking of axle loads and vehicle gross weights of commercial goods traffic. Potentially overloaded vehicles are specifically removed from the flow of traffic and re-weighed at monitoring stations using calibrated scales.

WIM-P systems only require 2 lines of Lineas sensors per lane. Depending on the customers requirements these systems can be equipped with ANPR and overview cameras.

Weigh In Motion Statistics (WIM-S)

Weigh-In-Motion statistic systems (WIM-S) are used to capture the traffic in total as well as the data of each individual vehicle. WIM-S can be seen as the bottom of the range of WIM systems.

WIM-S systems only require 2 lines of Lineas sensors per lane. In general these systems aren´t equipped with cameras.

Sensor Arrays

The WIM-DSP 32 supports an array of up to 32 Lineas sensors which can be arranged in any configuration. Known sensor geometries enable different wheel tracks to be combined – in the simplest case, the left and right neighbouring tracks.

The scenarios described above can also be supplemented by sensors installed at an angle to determine the position in the lane and to establish the type of tyres (single or twin tyres).

Sensor arrangement for Weigh in Motion Enforcement, lane changing (left) correct traversals (right)
Staggered sensor arrangement

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dynamic wheel load scales, weigh in motion, WIM, overload, road damages, Kistler, Lineas, charge amplifiers, ruts, lange grooves, COST 323, TLS 2012, OIML 134, WIM-S, WIM-P, WIM-E, statistics, preselection, enforcement, police, BASt, Federal Highway Research Institute, Federal Office for Commercial Transport, BAG