# Dynamical Effects of the Increase of the Axle Load on European Freight Railway Vehicles
## 1 Introduction  
The European rail freight transport market is constantly evolving on the basis of the measures that the Community regulatory body has progressively introduced (first and second infrastructure package). Continuously it is reiterated that the strengthening of the rail transport mode is a priority action with a view to sustainable and eco-compatible development. The \"White Paper on Transport\", issued by the European Community in March 2011 [1], contains fundamental points that lead to further study of the issues treated in this paper. It is expected that freight transport will grow by 40% from 2005 to 2030 and by just over 80% by 2050. Passenger traffic is expected to register a slightly lower increase: 34% by 2030 and 51% by 2050. The document states that 30% of the transport of goods exceeding a travel distance of 300 km, must be converted by 2030 to rail and/or sea. By 2030, the TEN-T network for intermodal freight transport must be completed. The aim is to promote a common rail transport market, overcoming current barriers and technological constraints that prevent interoperability, and aiming for effective competition in services at the European level. Rail transport suffers from the high operating costs it is characterized by, for which it is necessary to improve its economic performance. One of the methods is to increase the transport capacity proportionally higher than the differential in operative costs that this increase produces. The increase in capacity, here intended as the number of tonnes per day transportable between two points of the network, can be realized in different ways. The possible solutions that can be proposed are the following:* Increase the frequency of trains;
* Increase the vehicle speed;
* Increase the length of the train;
* Increase the axle load of vehicles;
* Reduce vehicle tare load (non-paying load);
* Increase the number of axles on the train/vehicle. For example, freight traffic on the American continent, where experiences of axle load increase date back to the 1970s and train composition with axial weights up to 35 tonnes/axis are now part of a consolidated experience [2], is mainly related to freight vehicles adopting the typical North American bogie, namely, the three-piece truck [3; 4]. In other countries such as China, Australia, and Russia, vehicles based on the same type of bogie are already adopted for high axle loads, up to 40 tonnes [5], or technologies to increase the axle load will be developed [6; 7]. In this work, we tried to understand in mechanical terms what the effects are on the infrastructure of an increase in axial weight on conventional European freight vehicles. The test is performed considering the characteristics of Italian lines, where vehicles are allowed to run with a maximum axle load of 20 tonnes. As regards the increase in load capacity [8], the EU's efforts to move in this direction are evident, passing first from 20 to 22.5 tonnes/axis according to studies promoted by the ERRI (European Rail Research Institute) [9; 10]. Moreover, Swedish railways, exceeding the international UIC considerations, have increased the load per axle to 25 tonnes [11; 12]. This limit was also taken into account by the European railway regulatory committee (UIC) [13], and later this value was included in the EN 15528:2008 standard [14]. On the other hand, the Technical Specification of Interoperability (TSI) for freight wagons, published in the official journal of the European Union on 2006 (2006/861/EC) [15] and later updated [16], introduces new categories of line E, F, and G with subscript 5 and 6 with an axle load, respectively, of 25 tonnes, 27.5 tonnes, and 30 tonnes. These categories of lines are not considered in the UIC leaflet 700 edition 2004 [17], (the standard for the European networks ex RIV). In this leaflet, which characterizes most of the high-capacity lines in the EU, the permissible load is limited at the category D4.