The aim of the HyTunnel-CS project is to perform pre-normative research for safety of hydrogen driven vehicles and transport through tunnels and similar confined spaces (FCH-04-1-2018). The main ambition is to facilitate hydrogen vehicles entering underground traffic systems at risk below or the same as for fossil fuel transport. The specific objectives are: critical analysis of effectiveness of conventional safety measures for hydrogen incidents; generation of unique experimental data using the best European hydrogen safety research facilities and three real tunnels; understanding of relevant physics to underpin the advancement of hydrogen safety engineering; innovative explosion and fire prevention and mitigation strategies; new validated CFD and FE models for consequences analysis; new engineering correlations for novel quantitative risk assessment methodology tailored for tunnels and underground parking; harmonised recommendations for intervention strategies and tactics for first responders; recommendations for inherently safer use of hydrogen vehicles in underground transportation systems; recommendations for RCS. The objectives will be achieved by conducting inter-disciplinary and inter-sectoral research by a carefully built consortium of academia, emergency services, research and standard development organisations, who have extensive experience from work on hydrogen safety and safety in tunnels and other confined spaces. The complementarities and synergies of theoretical, numerical and experimental research will be used to close knowledge gaps and resolve technological bottlenecks in safe use of hydrogen in confined spaces. The project outcomes will be reflected in appropriate recommendations, models and correlations could be directly implemented in relevant RCS (UN GTR#13, ISO/TC 197, CEN/CLC/TC 6, etc.). HyTunnel-CS will reduce over-conservatism, increase efficiency of installed safety equipment and systems to save costs of underground traffic systems.