Dynamic axle load scales
Dynamic vehicle weighing (Weigh-in-Motion) focuses on monitoring compliance with the statutory regulations, the safety of road users, and the protection and long-term preservation of the traffic infrastructure. For enforcement and tolling applications based on OIML R134-1, these systems are referred to as independent dynamic Weigh-in-Motion systems. For pre-selection and statistical applications based on COST 323 they are referred to as dynamic axle-load scales.
In 2016, Traffic Data Systems was the first company in the world to receive OIML R134 certification for an independent Weigh-in-Motion system which covered the speed range from 5 km/h to 120 km/h or 140 km/h, which enables these systems to be used on motorways.
The continuous overload monitoring of heavy goods vehicles (HGVs) is gaining in importance throughout the world. In order to be able to prosecute violations in court, these independent Weigh-in-Motion systems based on OIML R134-1 must be certified by a national metrological institute accredited for this technology.
The WIM-DSP 32 has been certified by METAS in accordance with the requirements of OIML R134-1. Today, Traffic Data Systems is the only manufacturer in the world to have a certified and verifiable low and high-speed Weigh-in-Motion system with only 3 rows of sensors which not only covers the requirements of OIML R134-1 (Class F/10), but also the speed range from 5 km/h to 120 km/h for heavy goods vehicles required by the Technical Conditions of Supply for Roadside Remote Stations (temperature range: -30°C/+75°C at up to 85% relative humidity). For light goods vehicles, the certified speed range is 5 km/h to 140 km/h.
The system fulfils the requirements of OIML R134 Class F/10. This corresponds to a maximum measuring error of ±5% (initial verification) or ±10% (in-service inspection). For Switzerland, Traffic Data Systems has obtained type approval CH-W7-17844-00 as part of the OIML certification. Type approval (No. 987/2017) from the Metrological Institute of Latvia ‘LATMB’ has also been obtained.
Type approvals are a prerequisite for national certification and calibration by the local government authorities. Three rows of Lineas sensors are required for enforcement and tolling applications in order to satisfy the requirements prescribed by OIML R134-1.
As well as precise vehicle weight measurements, the traversal documentation (timestamp, photo, video sequence and number plate recognition) along with a record of external influences form the core elements of such systems for enabling ‘events’ to be documented for use as evidence in court. They also allow any interference effects (storm gusts, braking manoeuvres etc.) to be recorded and the data record to be identified appropriately.
Sensors installed at an angle at the end of the sensor field enable evidence of the position of the vehicle in the lane to be provided and single or twin tyres to be detected.
The WIM-DSP 32 is the first and, to the present day, only Weigh-in-Motion system, to have long-term sensor monitoring (PSHC). It has been developed specially for use with Kistler Lineas sensors and charge amplifiers. Configuration and functional control is carried out using touch keys on the integral colour graphics display or by means of a notebook.
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 performance features, the WIM-DSP 32 sets new standards in the Weigh-in-Motion system market.
Independent Weigh-in-Motion systems for enforcement and tolling applications must be equipped with a RWIS system, as correct measurement of the wheel, axle and gross weights is not possible under certain weather conditions (snow, ice, heavy rain, storm gusts etc.). In these weather situations, data gathering is suspended until reliable data can be measured once more.
In Germany, the monitoring of heavy goods traffic is carried out by special state police units and the Federal Office for Goods Traffic (Bundesamt für Güterverkehr – BAG). As well as checking vehicle and transport documents, technical condition of the vehicle and load safety, these specific checks focus on monitoring the axle loads and gross weights.
With the help of preselection systems (WIM-P), overloaded vehicles can be automatically or manually diverted out of the traffic flow, and the vehicle weights documented for use as evidence in court at a dedicated check-in area using calibrated scales.
These systems are also used for monitoring on bridges. There are various bridges over which heavy vehicles are not allowed to travel for age and/or construction reasons. With the help of WIM-P systems, these vehicles can be detected and diverted at an early stage. As an option, the units can be equipped with different camera systems in order to provide overview images or automatic number plate recognition.
The recording of overall vehicle and individual vehicle weight statistics (WIM-S) is continuously gaining in importance, as road and bridge infrastructure maintenance has not kept pace with the growth rate of individual traffic in recent years and decades. Already, some bridge structures can only be used to a very limited extent, thus necessitating a 24/7 monitoring of vehicle weights using appropriate systems.