Passenger and freight traffic on German railways is closely timed; as a result, the rail networks are under heavy strain and in many places are not in the best condition. Renovating sections of track and opening up new routes is a lengthy and cost-intensive process. It is therefore particularly important to protect the rail networks and prevent excessive stress and wear. For example, overweight or one-sided loading of trains or wagons are partly responsible for wear and tear on the rails and also represent a safety risk, both for the train and for the infrastructure, such as railroad bridges.

Following successful tests at the French SNCF, Althen has also brought the AWIM (Althen Weighing in Motion) dynamic weighing system onto the rails in Germany. On the one hand, it ensures that freight trains and wagons remain operational for as long as possible and, on the other, it helps to reduce the strain on rails and points.

Sensors certified according to OIML R106-1

The system is used to weigh locomotives and wagons, particularly freight trains, at speeds of up to 140 km/h as they pass over the weighing station attached to the rails. Eight weighing points based on force sensors enable precise recording of the weight and weight distribution per locomotive, wagon, axle, wheel and side. The sensors are certified according to OIML, an international standard for weight measurement of the International Organization of Legal Metrology. OIML R106-1 is specific to the rail sector.

In detail: The weighing method is based on force transducers mounted on the rail web. The patented strain gauge included detects the mechanical movements of the rail as the train passes over it and converts this information into analog, electrical signals. Each weighing point is connected to an analog/digital signal converter via a cable. The eight signal converters send the digital signal in real time to an electronic evaluation unit, which analyzes the signals and converts them into weights using algorithms. Weighing can be activated both manually when the train passes and automatically.

The accuracy of the system has been tested by the Research Institutes of Sweden and the Swedish mining company Lu-ossavaara-Kiirunavaara Aktiebolag LKAB. Depending on the speed, the accuracy is 0.5% (at speeds below 10 km/h) to 1% (at around 100 km/h).

The components installed on the track are supplemented by a system cabinet directly on the track and a MySQL database server in a local network or in a cloud. The system cabinet can be mounted directly on a wall or on a mast. The force transducers are connected to the system cabinet via a signal and power supply cable, which in turn ensures data transmission to the database/controller via an Ethernet connection. The analysis software for interpreting the measurement data is integrated into the system and can be combined with any of the customer's ERP systems and IT landscapes via appropriate interfaces.

Lifecycle management of all wagons

Eight pairs of sensors - four on each side of the track - record the weight and weight distribution per locomotive, wagon, axle, wheel and side. This allows loads on the infrastructure to be determined and predictive maintenance measures to be taken.

© Althen

The primary aim of the AWIM system is to measure weight. Thanks to the specific analytics behind it, further insights can be gained about wagons and rails: For example, the cloud-based data collected can be used to detect flat spots on the wheels - i.e. damaged areas on one side - through which the respective wheel exerts impacts on the rail. The system can also be used to detect possible derailments of individual axles. Both can have a massive impact on the rails. The early detection of flat spots and worn components helps to prevent sudden failures and repair damage in good time as part of predictive maintenance. This means that wagon maintenance can be planned and only carried out when the measurement parameters indicate that it is necessary.

Infrastructure monitoring is very time-consuming and, above all, cost-intensive for rail operators. With Weighing in Motion, operators save on maintenance and repair costs by bringing wagons into vehicle maintenance at exactly the right time thanks to the measurement data. In addition, critical infrastructure such as railroad bridges can be better protected: If the weight is checked before the train passes, the speed can be reduced if the weight is exceeded.

Predictive maintenance

The system has a built-in locomotive and wagon database for identification and traceability. This compares the distances between the passing wheels or axles and can then determine which axles belong together, thereby defining a locomotive or a wagon. In this way, the vehicle data is recorded and evaluated over the lifecycle.

The weighing system can provide operators with the following information:

• Identity, date and time of the weighing station;
• the direction and speed of the train
• the weight of each individual wheel and the weight of the bogie;
• the individual locomotive/wagon and total weight of the train;
• the number of passing axles;
• uneven loading and overloading; and
• the type of locomotive and/or wagon.

The author: Michaela Wassenberg is a freelance journalist from Nuremberg.

© Wassenberg PR

The system automatically compensates for temperature fluctuations and stresses in the rails and can be used in a temperature range from -30 to +80 °C. It is insensitive to weather conditions. It is insensitive to weather influences. Even driving over the weighing station at high speeds, for example with an ICE train, does not affect or damage the sensors. This results in a high degree of freedom when positioning the force transducers on the rail.

In addition to the Deutsche Bahn rail network, the dynamic weighing system is also suitable for private rail networks such as in the steel industry, at ports or in coal mining: on the one hand, operators can plan maintenance and servicing with foresight and, on the other, the system is also useful for calculating the loading of raw materials.