# Risk Assessment in the Design of Railroad Control Command and Signaling Devices Using Fuzzy Sets
## 1 Introduction  
The proper functioning of the economy requires an efficient and safe transport system, in which rail transport plays an important role. In this context, the fact that many investments in rail infrastructure are currently being made in Poland should be evaluated very positively [1]. However, these are difficult investments for both technical and formal reasons. In technical terms, they cover three large areas often implemented, to some extent, independently:  
* Railroad (tracks and sub-tracks) together with engineering structures (e.g., bridges, embankments, crossings);
* Traction power supply (catenary power systems and catenary networks);
* Traffic control systems (including signal boxes and traffic control systems), operational communications systems, and supporting teletechnical systems. The above areas, in accordance with European requirements [2], are defined as structural subsystems that form the infrastructural part of the railway system [3]. In the formal dimension, the investments in question are carried out simultaneously in accordance with the rigors of the construction law and in accordance with the requirements of the Railway Transport Act [4], as a result of which their completion requires obtaining both construction permits for use and railway permits for commissioning. Railway investments are complex and multi-stage. he investment process requires meeting many requirements in accordance with national and European law in order to achieve the required level of traffic safety. Therefore, investment processes involve various risks. Each investment has its own multiple technical and operational conditions that should be taken into account at the earliest possible stage of implementation. Therefore, it is not possible to develop one universal rail traffic control system defined in detail at theapplication level. Each implementation is, in many respects, \"tailor-made\" for a specific single location. For this reason, it should be considered appropriate to develop a solution or solutions based on risk management in investments introducing changes to rail traffic control systems. The railway system consists, among other things, of various structural subsystems. These subsystems are usually covered by investment processes, and one of the most serious challenges in the implementation of railway investments is railway traffic control systems (control command and signaling subsystem). They must be compatible with track systems but also adapted to future operational needs from the point of view of the possibility of simultaneous implementation of different train routes. They must be protected against interference, including interference from traction currents. They require their own power supply and significantly affect teletechnical installations, for example, due to numerous cable collisions [1]. For these reasons, the preparation and implementation of investment works in the field of railway traffic control are the domain of a few specialized business entities. Such entities, in many cases, have to cooperate with construction contractors with limited knowledge in the field of rail traffic control and sometimes even specialists coming from the road or even the development market, as well as companies building teletechnical installations that have never dealt with rail transport before. At the same time, the increase in the number of investments requires building new teams directly dealing with rail traffic control systems. In order to ensure significant support for existing and new teams designing and implementing rail traffic control systems, solutions supporting the introduction of changes in rail traffic control as part of investments should be developed. For several years, due to the requirements of European law, it has been required to apply risk analysis [5] to changes in the railway system. It is assumed that this should increase the awareness of the participants in the investment process and thus reduce the level of risk.