Given the essential role that road tunnels play in a road network in supporting the mobility of people and goods, following a traffic accident, the non-availability of a tunnel for the passage of traffic flow through it is a relevant issue for the social and economic interests of the community. Road tunnels that present an adaptive response to a disruptive event (e.g., a traffic accident) are generally described as resilient. There is no shared concept of resilience in the current literature. However, with respect to infrastructure networks, resilience may be described as \"the ability of a system to rapidly recover its functionality after a disturbing event\" [7]. Resilience of a transportation system has been investigated from different perspectives. Some researchers, for example, have discussed the most appropriate metrics for assessing the resilience of an infrastructure network [7; 8; 9; 10]. [PERSON] et al. [11], and [PERSON] et al. [12] focused, instead, on traffic flow simulation models to investigate both the robustness of a road system as well as the effectiveness of different management strategies. [PERSON] et al. [13], and [PERSON] et al. [14] proposed frameworks to evaluate the resilience of a road network. [PERSON] et al. [15] concentrated on the resilience and vulnerability of transportation networks. [PERSON] et al. [16] found the optimal location of road guidance tools for re-routing vehicular flow after a disturbing event. [PERSON] et al. [17] developed a methodology to evaluate the effectiveness of diversion on the resilience of a road network. [PERSON] et al. [18] investigated the redundancy of a transportation network, while [PERSON] and [PERSON] [19] concentrated on both the robustness of a network and the rapidity of the recovery process. [PERSON] et al. [20] proposed a method for setting traffic signals in order to improve resilience. [PERSON] et al. [21] set up a stochastic simulation model to evaluate tunnel resilience, while [PERSON] [22] developed a genetic algorithm for optimizing a road network. PIARC [23] presented the current state of knowledge of road tunnel resilience, whereas [PERSON] et al. [24] investigated the resilience and emergency management of road tunnels. Finally, [PERSON] et al. [25] set up a traffic simulation model for evaluating the resilience of a twin-tube motorway tunnel in the case of a traffic accident in a tube. However, it is worth highlighting that, among the studies referred to, only a few have focused specifically on the resilience of road tunnels, such as [PERSON] et al. [12], [PERSON] et al. [21], PIARC [23], [PERSON] et al. [24], and [PERSON] et al. [25]. Moreover, as far as the authors of this paper are aware, there are no studies in the current literature in which the restoration of the functionality of a tunnel (i.e., resilience) in the event of a traffic accident is also associated with user safety that might be compromised, for example, by a fire of vehicles transiting on the remaining undisrupted lanes of the partially closed tunnel. Furthermore, in the case of a twin-tube road tunnel in which a tube is completely closed due to a traffic accident, the resilience of the tunnel system has not been evaluated in combination with occupant safety that may be affected by a fire affecting vehicles that, having changed carriageway, use one lane of the adjacent tube to travel (i.e., where bi-directional traffic conditions are generated in the parallel tube). This represents a lacuna of knowledge that this paper seeks to fill. With reference to our previous studies, it is also worth highlighting that we did not investigate user safety in the earlier paper [25], while in other studies, we evaluated only the safety level of tunnel users in the event of a fire (e.g., [PERSON] et al. [26; 27; 28; 29; 30; 31; 32], [PERSON] and [PERSON] [33; 34; 35; 36], and [PERSON] and [PERSON] [37]), but not resilience.