## 5 Conclusions
The integration of technologies that have proven to be successful through research projects is moving in the direction of digitisation, which is key to the competitiveness of the railway industry, and that is why it has become one of the priorities that stakeholders in the railway system deal with in order to use technological opportunities to improve operational processes, i.e., the quality of the provided transport services. The modern information and communication systems mentioned in the paper are focused precisely on applications in different business verticals, where transport in general, especially environmentally friendly rail transport, plays a major role. Modern railway systems will largely apply communication technologies of the latest generations paired with new data sources and the application of data science, including artificial intelligence (e.g., fuzzy logic) in order to optimise processes and provide a competitive, reliable, safe, and environmentally sustainable transport service. The digitisation of railway processes, driven by the application of mobile communication networks and information-communication systems, generates a sufficient amount of data on the basis of which it is possible to extract and use those that are important for the improvement of operational processes in railway systems. Finally, the role of the Industry 4.0 concept was investigated within the framework of railway transportation. In that respect, the role of information and communication technologies was investigated for the case of autonomous trains and automated railway traffic, wherein big data analytics and latest next generation communication technologies ought to play key roles in future railway transportation. The same conclusion can also be drawn in the case of multimodal transportation combining railways with other modes of transport, with a particular emphasis on the role of new technologies in improving the energy, economic, and ecological indices. In that sense, the utilisation of optimisation tools may be the key to achieve more efficient, economic, and cleaner transport. On the other hand, when transportation safety is concerned, the predictive maintenance of railway vehicles and infrastructure represents one of the key prerequisites for future transportation safety. In that sense, intelligent sensor networks coupled with big data analytics and artificial intelligence may provide timely information about equipment and infrastructure condition deterioration. Obviously, this may also have a profound effect on the railway network and transportation system resilience. In that sense, the utilisation of specialised sensors, machine learning and artificial intelligence, and innovative platforms for the inspection and surveillance of critical railway infrastructure should play key roles in future intelligent transport. The utilisation of intelligent Industrial IoT sensors and smart metering is also vital for the introduction of the smart grid concept into the railway transportation sector. Such synergy between intelligent transport and intelligent energy management is likely to usher many improvements in energy efficiency and transportation security and safety. For that to happen, it is crucial that ICT systems for railways can support both narrow-band and broad-band communications with enhanced security features to support the integrated smart railway transport and energy infrastructure. Conceptualisation, M.N. and D.P. ; methodology, M.C., Z.K., and T.J.M. ; investigation, Z.K., D.P., M.T., M.C., and M.N. ; resources, D.P. ; writing--original draft preparation, Z.K. ; writing--review and editing, D.P., M.C., M.T., and M.N. ; visualisation, Z.K., D.P., and M.C. ; supervision, T.J.M. ; project administration, D.P. ; funding acquisition, D.P. All authors have read and agreed to the published version of the manuscript. This research was funded by the European Regional Development Fund (ERDF) under the grant KK.01.1.1.01.0009 (DATACROSS). This is a review article, so no new data were created or analysed in this study.