Road Tunnels Operation: Effectiveness of Emergency Teams as a Risk Mitigation Measure

Managing a major event in a road tunnel requires more resources than an open-air event. In the case of fire, the confined environment of road tunnels can represent a critical situation for both users and rescuers. The safety level of a tunnel can be estimated by using dedicated risk models that consider, on the one hand, the traffic (type, quantity and distribution) of a tunnel and, on the other hand, the structural and plant safety measures. According to the European Directive, road tunnel managers can adopt additional safety measures aimed at increasing the level of safety for users exposed to the consequences of an accidental event. One of these measures is the rapid intervention of emergency teams located in the proximity of the tunnel. These teams use pick-up and scooter vehicles properly equipped to cope with a fire event and have detailed knowledge of the specific tunnel system. A further advantage of the emergency teams is the possibility of supporting the evacuation of tunnel users by providing indications on emergency exits, bypasses and safe places considering the evolution of the specific event. In this perspective, the present research contributes to the evaluation of the emergency teams’ effectiveness. Thus, the emergency team was included as a safety measure within a risk analysis model for road tunnels developed by the authors in previous works. After an analysis of the technical and scientific literature, we focused on 15 interventions carried out on some highway tunnels in Italy between the year 2019 and the year 2021. The intervention times of the teams were analyzed using data provided by Strada dei Parchi S.p.A., a company that manages 14 highway tunnels in Italy. These 14 tunnels range in length from 589 m to 10,121 m and are subject to the European Directive. The observed intervention times of the emergency teams range between 2 min and 10 min with an average value of 5.9 min. Such a short intervention time is possible because emergency teams are in the proximity of the different tunnels. Because of the short intervention time and the training of the personnel, all the fires were properly managed by the teams. Furthermore, considering the results of the scientific literature and the data presented in this work, it was possible to estimate and validate an effectiveness value (higher than 90%) of the emergency teams to be used within the risk analysis model developed by the authors and which can also be used in other risk analysis models

Safety in Road Tunnels: Accident Data Analysis of the Italian Motorway A24 and A25

This paper illustrates the accidents data observed in 14 road tunnels of the Italian motorway A24 and A25, with particular emphasis on two top events such as fires and release of dangerous goods. Consistent data regarding this kind of events are essential to improve the reliability of quantitative risk analysis models for road tunnels. According to the European Directive 2004/54/EC, a quantitative risk analysis (based on accidents data) is required for tunnels belonging to the Trans-European Road Network and longer than 500 m. This work illustrates the accidents occurred inside the 14 tunnels of the A24 and A25 motorway in the years 2012-2018 (7 years), taking into account the different length of the tunnels and the specific traffic of each section of the track. These data can be used by analysts and researchers for quantitative risk analysis purposes using the Event Tree Analysis (ETA) technique. In particular, the observed data are useful to make a comparison with results estimated using analytical models. Finally, the consistency of the estimated accident rates is evaluated by a comparison with literature results

RESILIENCE AND EMERGENCY MANAGEMENT OF ROAD TUNNELS: THE CASE STUDY OF THE SAN ROCCO AND STONIO TUNNELS IN ITALY

In Italy, mainly due to its complex orography, there are more than 50% of road tunnels longer than 500 m belonging to the Trans European Road Network. Moreover, many road tunnels were designed and built several years ago, where both traffic flows and vehicle sizes were different. Generally speaking, it is possible to state that if on one hand road tunnels allow the improvement of the plano- altimetric coordination of road layouts, on the other hand they can represent a safety problem for users and for the infrastructure in case of a major event. With this in mind, it is interesting to study the resilience of a road tunnel following an event: how can the resilience of a tunnel be increased by considering emergency management? How can negative consequences be reduced by adopting specific safety measures, such as emergency teams? Starting from these two questions, the main goal of this work was to analyze two fire events that occurred in two tunnels located on the A24 highway in Italy between 2019 and 2021 and managed by Strada dei Parchi S.p.A. Both fires involved a light vehicle and there were no injuries or fatalities. For each of the two events, the response time of the emergency teams and the resolution time of the event were analyzed. In the first case it is possible to evaluate the effectiveness of the emergency teams in controlling and/or extinguishing a fire, while in the second case the impact on road traffic caused by the tunnel closure is analyzed. These analyses can be used for two important purposes: (i) risk assessment of a tunnel considering the emergency team as a safety measure; and (ii) implementation of traffic management plans to define the best strategy to be adopted according to the estimated time of closure of a tunnel

Tunnel Risk Analysis: a Quantitative Evaluation of the Effectiveness of Emergency Teams Inside the A24 and A25 Motorway Tunnels

The European Directive 2004/54/EC - concerning minimum safety requirements for tunnels on the trans- European road network - requires a quantitative risk analysis for tunnels belonging to the trans-European road network and longer than 500 m, based on accident data. Strada dei Parchi S.p.A. is a company that manages a large number of road tunnels belonging to the A24 and A25 motorways in central Italy. In the course of recent modernization work on several tunnels, Strada dei Parchi S.p.A. has decided to set up and train emergency teams as a measure to further reduce the risk to tunnel users. This paper discusses the effectiveness of emergency teams during major events, in particular fire accidents. The effect of emergency teams on road tunnel risk is assessed through a quantitative model implemented by Politecnico di Milano: TRAM - Tunnel Risk Analysis Model. The TRAM risk analysis model is able to assess the societal risk for the different tunnel configurations also taking into account the presence of emergency teams. Starting from two types of initiating events, fire and DG (Dangerous Goods) release, TRAM can consider up to 18 accidental scenarios occurring in different positions inside the tunnel under investigation. The main goal of the work is to analyze the effect of the presence of emergency teams in terms of reduction of the societal risk index for a representative tunnel; the resulting F-N (Cumulated Frequency - Number of Casualties) curves are also compared with the ALARP acceptance criterion. This study is divided into three main parts. The first part of the study describes the tunnel infrastructure and the equipment of the emergency teams; the second part is related to the description of the risk model with respect to the effectiveness of the emergency teams and, finally, the third part describes an application of this model to a case study. The effectiveness of the emergency teams and, in particular, their ability to control or extinguish the fire principles is analyzed using observations made inside the tunnels of the A24/25 motorways which were recorded and provided by Strada dei Parchi S.p.A

Safety in Road Tunnels: Analysis of Fire Accident Location inside the Gran Sasso Tunnel in Italy

The aim of this research is to analyze the fire events occurred inside the Gran Sasso unidirectional highway tunnel in Italy. The Gran Sasso tunnel consists of two parallel one-way tubes with a length of about 10100 m. The tunnel, managed by Strada dei Parchi S.p.A., is one of the 14 tunnels belonging to the A24 and A25 motorways subject to the application of the European Directive 2004/54/EC. This Directive requires a Quantitative Risk Analysis (QRA) for tunnels belonging to the Trans-European Road Network and longer than 500 m. This study analyzed the fires and fire principles (which failed to develop into fire) that occurred in the left tube of Gran Sasso tunnel during the period 2007-2020, which consists of an uphill section of about 4500 m followed by a slightly downhill one. These events involved both light and heavy vehicles; their location along the tunnel and the possible causes were considered. Out of the 12 events analyzed (6 fires and 6 fire principles) it was observed that 11 events occurred in the uphill section while only one event occurred in the downhill section. The results of this study can be used for the implementation of risk analyses according to the European Directive but can also represent a useful tool for tunnel managers to evaluate the possible increase in the number and location of fire detection devices and/or fire suppression/control systems