**3. Wagon 4.0 concept**

The development and the concept of Wagon 4.0 (W40) are largely driven by the interest to maintain an attractive freight rail system despite adverse trends such as autonomous lorries or reduced amounts of mass goods to be transported. The main aim of the work is to improve the competitiveness of single wagon loads, as this is to be considered a major driver of future logistics demands [9].

The W40 is based on conventional freight wagons, with conventional bogies and couplings according to local standards. It generates much of its added value, thanks to its local control hardware and software, supplied by a wheelset generator with a buffer battery as well as sensors, actuators, communication units and a shunting drive.

The W40 is self-sufficient, self-aware and recognizes other W40 in its vicinity. Thanks to a battery that is charged during mainline operation, it is also smart when stationary and without a locomotive. Due to the operating system and other interfaces to the power supply, it can be optimised for various applications.

Details about the staged introduction scenario, using the idea of classes as well as more information on potential advantages in mainline operation can be found in the tripartite paper [10–12].

The W40 is based on five key structural elements, which are as follows:

1.Power supply: Electrical power plays a vital role in automation as well as in condition monitoring. Freight wagons are typically unpowered assets. In order to have sufficient power for a variety of actuators, a 24 V power network supplied by electricity produced by local generators and stored in local batteries is implemented for W40 with a standardised architecture defined in Ref. [13].


 The W40 concept follows a class structure aiming to modularise the system, ease introduction into fleets and allow the selection of the most appropriate and economical class for a certain wagon or fleet. **Figure 5** shows a schematic of a W40, indicating the class of the respective functionality.

 The classification starts with a W40 of class 1, allowing communication with and over this wagon. A class 2-W40 adds an interface to the brake system, including measurements of brake cylinder and brake pipe pressures as well as the remote activation of brake mode or empty-loaded selection. A further sensible addition to the system is the so-called ep-light brake, an indirect electro-pneumatic brake. This is the only additional functionality of class 3 over the other classes. A class 4 wagon aims to fully automate the wagon subsystem with an additional end-of-train signal, whereas a class 5 wagon adds a drive system to enable automated movements in the siding.

 **Figure 5.**  *Wagon 4.0 structure and functional classes.* 
