Safety solutions for Smart tunnel: green island, technical devices, and technological systems for sustainable development goals

We are thus addressing the safety of citizens who, when passing through a tunnel, expect to be assured of the system's proper functioning. They want their decision to use the tunnel to represent an acceptable level of risk. How are these tunnel safety studies conducted? Primarily through simulations. This involves analysing airflow patterns, material behaviour, the presence of transport vectors within the tunnel, fire development, and more. These are studies rooted in physics and applied chemistry. The phenomena at play can be simulated on a computer and compared with experimental data obtained from controlled fire tests conducted in test tunnels, specifically designed to study the various processes involved. As the French say, it is about "preventing rather than curing." This leads to the fundamental concept of the intelligent tunnel—one that continuously "knows" what is happening inside, that "understands" what is moving between its entrance and exit, including any heavy vehicle loads. This research addresses the critical need for innovative safety solutions in the design and operation of smart tunnels, focusing on the integration of green technologies and technical devices that support the sustainable development goals (SDGs). The study begins by analyzing the concept of risk in the context of road tunnels, with a particular emphasis on risk-based design. An examination of major accidents in road tunnels highlights the importance of effective risk management and adherence to both European and Italian legislative frameworks (Directive 2004/54 and Decree 264/2006). The research introduces the bow-tie model as a foundational tool for risk analysis, exploring its application in road tunnel safety scenarios. Special attention is given to the dependability of safety systems and the contribution of asphalt pavement in risk mitigation, supported by an experimental case study. This path is particularly important as it forms the foundation for implementing the research's novel contributions. In the second section, the focus shifts towards the concept of the smart tunnel, aligned with sustainable infrastructure principles. The study reviews existing literature on green tunnel solutions, with particular attention to renewable energy sources, zero-energy tunnel designs, and safety lighting systems. The integration of sustainable technologies into tunnel infrastructure is a key aspect of ensuring both safety and environmental responsibility. This phase is preliminary to understanding how the introduction of alternative technologies could impact the design of tunnels in operation or newly opened ones. This path is particularly 14 important as it forms the foundation for implementing the research's novel contributions.A significant portion of the research is dedicated to fire safety in tunnels. This includes a comprehensive review of fire tests in tunnel environments, covering fire suppression technologies, ventilation systems, and water-based firefighting solutions. A detailed investigation into water mist suppression systems is conducted, with a focus on full-scale fire tests, Fire Dynamics Simulator (FDS) modelling, and theoretical modelling The third section/part presents the core contribution of this PhD thesis, in introduction of innovative and conceptual of a Decision Support System for road tunnels, with a focus on its potential to enhance safety and sustainability. The DS4T (Decision Support for Tunnels) is designed to provide real-time data and analytics for effective decision-making in critical infrastructure. The system’s integration of green devices and technological innovations aims to improve both the resilience and sustainability of tunnel infrastructure. The fourth and final section presents a detailed case study of a tunnel, which is a tunnel placed in Italy, having a touristic relevance. The case study includes an overview of the fire test design scenario, preliminary testing, and CFD simulations. The final fire test results are analyzed, demonstrating the effectiveness of the proposed safety solutions and their applicability to real world tunnel environments. The findings underscore the importance of integrating innovative safety technologies with sustainable practices to achieve a comprehensive approach to tunnel safety and fire resilience.