The connection of the Turin-Ceres railway (Gruppo Torinese Trasporti) with the Turin railway network (Rete Ferroviaria Italiana) represents important underground works of approximately 4.2 km, involving the entire Turin Railway Node. The critical issues related to the interconnection of two different railway systems required the elaboration of an extensive risk analyses, consistent with the requirements indicated by D.M. 28.10.2005 “Safety in railway tunnels”. The analysis includes the verification of compliance with the safety requirements, the determination of the expected risk level for the three events envisaged by the D.M./2005 (derailment, collision, fire), an estimate of possible additional measures which may be necessary to achieve the objectives and an assessment of these measures through a cost-benefit balance. For the case of fire, numerous 3D fluid dynamics simulations of smoke and heat propagation and specific escape models in the different scenarios, established according to “logical tree” structures on several levels and necessary to estimate the probability of occurrence of each event, have been developed. The elaboration of the analysis allowed to verify that the expected risk level, calculated for the infrastructure in question, can be reduced through the adoption of supplementary measures, determining which of them are reasonably practicable.