Railways simply explained
15. 11. 2023
Did you know that railway routes are divided into route classes? And why freight wagons must not exceed the maximum payload limit? The following article explains what route classes are and how they are related to the maximum permissible axle load.
In 2017, 69 domestic and foreign railway undertakings covered 164 million train kilometres on the Austrian rail network. That equals 4,000 circuits of the Earth in one year. The rail network must therefore be able to withstand a lot when freight or passenger trains weighing several tonnes roll over the rails at high speed. But not all trains are allowed to run unrestrictedly on all lines. In the rail world, certain conditions apply in order to guarantee safe rail freight traffic.
An essential prerequisite for a sustainable train service is the construction and maintenance of a modern rail infrastructure. For example, the rail network itself, i.e. the substructure and superstructure, must be designed accordingly for both high-speed passenger traffic and heavy freight traffic. To this end, railway routes are divided into route classes according to their load capacity. The route class determines the maximum permissible wheelset load and metre load of a line. The wheelset load or load limit provides information on the maximum weight per axle or the maximum permissible weight up to which a wagon may be loaded for the individual route classes. This is because the weight of the wagons and thus of a freight train depends on the load-bearing capacity of the superstructure and substructure of the respective section of track. The wheelset load of a wagon is the sum of the wagon’s own weight and the weight of the load divided by the number of wheelsets. In Austria, there are four line classes, ranging from class A with 16 tonnes axle load to class D with 22.5 tonnes axle load. Virtually all major routes in Europe correspond to Class D, while secondary routes are usually Class C. Classes A and B, on the other hand, hardly play a role any more.
The metre load, on the other hand, is determined by the load capacity of the bridges. It is the sum of the dead weight of the wagon and the weight of the load divided by the length of the wagon in metres.
In Europe, line class D4 with a maximum axle load of 22.5 tonnes and a load per metre of eight tonnes per metre has been defined as the standard for new and upgraded lines. In Austria, too, the majority of the rail infrastructure network corresponds to this route class, which enables the efficient transport of goods and passengers. The standardisation of the route class contributes to smooth cross-border train traffic and is thus indispensable for the European as well as the Austrian economy.
In the case of freight wagons, the possible payload thus depends on the route class, the load capacity of the wagon, the travel speed and its own weight. If the tare weight of freight wagons or wagon undercarriages is lower, as is the case with the modular rail freight car innovation TransANT, more payload is also possible. This is because the special lightweight construction and topology optimization of the TransANT enables a 20% lighter wagon underframe and up to four tonnes more transport volume per wagon. This means that even more goods can be transported by rail in an environmentally friendly manner.
