As NEXUS approaches the end of its formal project lifetime, one of the most important questions is what legacy it leaves behind and how its results can continue to evolve. Over the past two years, the project has explored how artificial intelligence, simulation, digital twins, cybersecurity and advanced automation can contribute to safer, more efficient and passenger-oriented metro systems. The challenge now goes beyond understanding the potential of these technologies. It is about creating credible routes from research towards validation, large-scale demonstration and, ultimately, operational deployment.
Developing such pathways requires looking beyond technological maturity and considering the operational context in which innovation must be adopted. A key overarching lesson from NEXUS is therefore that metro innovation must start with the operator, not the technology. Metro systems are safety-critical environments, and new solutions need to respond to real operational needs while fitting with existing infrastructure, legacy systems, governance arrangements, procurement processes, cybersecurity requirements and public-authority priorities.
This principle shaped the acceleration work carried out with NEXUS partners Metro Genoa and Metro Sofia. The aim was to provide dedicated support to the operators in navigating the transition from research results to future demonstration and deployment opportunities. Starting from each operator’s strategic objectives, needs and constraints, the process worked backwards to identify relevant NEXUS results, the steps needed to mature and de-risk them, and the funding and innovation opportunities that could support their progression. A shortlist of candidate areas were considered before selecting one priority pathway for each operator.
In Genoa, the selected area was passenger-flow analytics and dynamic capacity management, with a possible pilot involving De Ferrari, Brignole and Principe. In Sofia, the priority was integrated passenger information, accessibility and journey guidance, linking metro information with real-time surface transport data. These were not conceived as ready-made investment projects, but as structured routes towards further technical assessment, validation, partnerships, governance and funding.
The work also exposed an important gap in the innovation chain. Research projects can develop promising concepts and technologies, while operators may be able to host large scale deployment. However, the intermediate step – full-scale, operationally relevant pilots capable of de-risking innovation – is often much harder to finance and organise. Yet these pilots are essential to demonstrate performance in real operating environments, test integration with legacy systems and build the evidence needed before operators commit to larger investments.
EU-funded projects can therefore act as accelerators, helping to bridge the gap between early-stage research and the large-scale demonstrations needed before procurement and deployment. In this regard, NEXUS explored different European funding and innovation pathways that operators could use as solutions mature, ranging from EIT Urban Mobility and the European Urban Initiative for testing and urban demonstrations, to future rail R&I programmes, including the successor to Europe’s Rail, and emerging instruments such as the forthcoming European Competitiveness Fund. The aim was not to identify a single funding source, but to help operators navigate a sequence of opportunities that can progressively move research towards validation and deployment.
Looking ahead, the concept of a possible NEXUS 2.0 has also been explored. Rather than repeating exploratory research, it could focus on integrating complementary NEXUS results into coherent operational use cases, demonstrating them through operator-led pilots, and preparing the evidence, governance, skills, partnerships and investment conditions required for wider uptake.
At the same time, the experience of NEXUS suggests a need for stronger support to metro-only operators within future European rail R&I programming. One possible step would be the development of a common European metro R&I agenda, bringing together metro operators, authorities, industry, research organisations and other relevant stakeholders to agree on the main research, innovation and deployment priorities of the subsector. This agenda could provide the basis for a more clearly identifiable metro strand within future rail R&I programmes, ensuring that calls, demonstrations and support mechanisms respond to the specific operational realities of metros. It could also strengthen support for operators with limited internal R&I capacity and create clearer routes from research to large-scale urban rail demonstration and deployment.