The power of accuracy

An advanced digital weight enforcement system provides highly reliable and accurate data to monitor and manage traffic, and protect road infrastructure from overloaded vehicles

Words | Christoph Klauser, Kistler, Germany

There is no doubt that roads are vital to supply people and industries with much needed goods. They are, however, under serious stress: overweight trucks cause heavy wear on road surfaces and bridges. This calls for effective ways to m onitor streets to protect critical infrastructure and enforce traffic regulation.

In 2020, almost 3.7 million tons of goods were moved via roads in Germany, making this traffic mode by far the most important in terms of logistics. The amount of transported goods has steadily increased over the past 20 years, and experts predict this trend will continue. This will put a heavy burden on road surfaces, because the number of overloaded trucks will grow accordingly. Overloaded trucks put a high strain on road surfaces as the impact of force per vehicle increases exponentially with higher axle load. This can result in potholes and cracks, which lead to frost weathering, or ruts, which increase the risk of aquaplaning. Trucks that exceed their permitted width or height or that drive with deflated tyres put other road users in danger. The rising traffic volume thus increases the demand for reliable and efficient direct enforcement systems.

Above: KiTraffic Digital contains proven WIM technology and sensors for vehicle count and classification

A digital breakthrough

For a long time, weight enforcement systems lacked accuracy, which hampered their wider use for direct enforcement. However, ler has made a breakthrough with its KiTraffic Digital WIM system. This is a digital platform that contains proven weigh-in-motion (WIM) technology, as well as sensors for vehicle count and classification. It offers unprecedented accuracy, enabling direct weight enforcement on a large scale.

As the first technology of its type available in the industry, the KiTraffic Digital WIM system has been awarded OIML R134 certification f or accuracy class F5 by the Swiss Federal Institute of Metrology METAS. This accuracy class indicates a maximum permissible error (MPE) of +/- 2.5% of the gross vehicle weight (GVW) during initial verification. The system was certified for a wide range of axle loads, ranging from 1 to 20 tonnes. The GVW is unlimited. Certified speed ranges are between 10km/h and 100km/h (6mph and 62mph) for heavy trucks, and up to 130km/h (81mph) for light vehicles and vans.

Though the OIML certificate is not binding for national legislations, it is widely recognized. The METAS institute operates within the

Left: Lineas Digital delivers uniform signals throughout the length of the sensing element because each single quartz is digitized and calibrated Below: KiTraffic Digital has already been successfully installed in Switzerland

framework of the ‘mutual recognition of national measurement standards and of calibration and measurement certificates issued by national metrology institutes’ (CIPM MRA). With the most recent OIML certificate, Kistler builds on its own legacy. The company had already achieved OIML certification in 2015 for its KiTraffic Basic WIM system.

Direct enforcement

The KiTraffic Digital WIM system opens the door to effective prosecution of hazardous vehicles on a large scale. The technology facilitates both the weighing of vehicles in motion without impairing traffic flow and the direct enforcement of overloaded trucks. As well as being an established WIM system, KiTraffic Digital combines Kistler’s tried and tested sensors with cuttingedge digital technology.

KiTraffic Digital comprises multiple rows of sensor strips based on unique digitalized Lineas WIM sensors. They are equipped with piezoelectric quartz crystals that are built in the road surface. The system calculates the wheel, axle and total weight of each vehicle with absolute precision, regardless of driving manoeuvres like lane changes. The quartz crystals supply data independently via a digital interface. Therefore, each crystal can be calibrated individually with no signal interference on the transmission path. Its accuracy of up to +/- 2.5% GVW allows for immediate identification and penalisation of weight violations.

A digital platform

The set-up of KiTraffic Digital is designed to ensure maximum robustness. Its core features are sensor health-status monitoring, standard industrial grade electronics, digital signal transmission and Power over Ethernet. KiTraffic Digital also operates without additional induction loops, which were required in the past. Here, the sensor itself detects the presence of vehicles and their classes. 3.7m The position of the force signal is also used to reliably detect single, dual, flat or mismatching tyres. The The weight of the total amount of goods – in metric system automatically records this information, thus providing a costtons – moved via road in effective tyre screening Germany in 2020 and enforcement solution that prevents potentially fatal situations. KiTraffic Digital also stands out for its flexibility. The system features open standard interfaces that allow for the easy integration into higher-level or third-party WIM systems. This makes it applicable for weight enforcement, toll-by-weight collection systems or traffic monitoring. As it compensates for poor road quality, there is almost no limit to its use. ■