Risk Analysis of One-Way Road Tunnel Tube Used for Bi-Directional Traffic under Fire Scenarios

Caliendo, Ciro; Russo, Isidoro; Genovese, Gianluca

doi:10.3390/app11073198

Cited by 8 publications

(10 citation statements)

References 32 publications

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“…Once the FDS tool was validated, a grid sensitivity analysis was carried out in order to identify an adequate mesh fineness. The results of this analysis, detailed in Caliendo et al [16,17], showed that the cubic cells of 0.4 m side were appropriate for correctly discretizing the investigated tunnel; in particular, 1,095,255 cells were used.…”

Section: Validation and Mesh Finenessmentioning

confidence: 98%

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A Numerical Study for Assessing the Risk Reduction Using an Emergency Vehicle Equipped with a Micronized Water System for Contrasting the Fire Growth Phase in Road Tunnels

2021

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We performed Computational Fluid Dynamics (CFD) modeling, and simulated a people evacuation process from a tunnel in the event of a fire, for evaluating the potentialities of using, as a temporary safety measure, an emergency vehicle equipped with a micronized water system for contrasting the fire growth phase. The structure investigated is a one-way road tunnel with only natural ventilation, and with a length less than 1000 m. The tunnel is assumed at present to be affected by refurbishment works for making it comply with the minimum safety requirements of the European Directive 2004/54/EC. In particular, it is considered that it has not yet been provided with hydrants, and with the sidewalks and the emergency exit which are still under construction. This means that users are forced to use the road carriageway for escaping from the tunnel if a fire occurs. The CFD findings have shown that the use of the micronized water system might lead to a significant improvement in the environmental conditions along the escape route since the tenability limits of temperature, radiant heat flux, CO and CO2 concentration were found to be better satisfied. Additionally, the visibility distance was shown to increase, even though it was found to be higher than the acceptable threshold value only in a few cases. However, the quantitative risk analysis based on a probabilistic approach, which was combined with a method currently used in Europe for assessing the risk due to the transit of only dangerous goods, shows that the final cumulative F-N curves related to the micronized water system always lie below those without the mentioned system, and in addition, they are always contained within the limits of the ALARP region. It is to be stressed that our paper might represent a reference in showing the effectiveness of the micronized water system as a temporary safety measure. However, it is desirable that the Tunnel Management Agencies accelerate the refurbishment works for making road tunnels definitively safer for users in a short period of time.

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Section: Validation and Mesh Finenessmentioning

confidence: 98%

“…); it is then followed by a constant HRR max phase. Details regarding the assumptions made for the yields of combustion products are reported in Caliendo et al [16,17].…”

Section: Fire Scenariosmentioning

confidence: 99%

A Numerical Study for Assessing the Risk Reduction Using an Emergency Vehicle Equipped with a Micronized Water System for Contrasting the Fire Growth Phase in Road Tunnels

2021

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“…Computational fluid dynamics (CFD) modeling is the most suitable tool for reproducing a fire; some of its applications, with reference to road tunnels, can be found in Caliendo et al [25][26][27][28][29][30][31]. In this paper, the Fire Dynamics Simulator (FDS) version 6.7.3 [45], which has been widely reported in the literature regarding the simulation of fires in road tunnels, was used as a CFD code.…”

Section: Fire Simulation Codementioning

confidence: 99%

“…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., Caliendo et al [26][27][28][29][30][31][32], Caliendo and De Guglielmo [33][34][35][36], and Caliendo and Genovese [37]), but not resilience. In other words, tunnel resilience and user safety were not coupled to each other; consequently, the effects of a strategy to recover the functionality of a tunnel that might influence user safety or vice versa were not considered.…”

Section: Introductionmentioning

confidence: 99%

A Simultaneous Analysis of the User Safety and Resilience of a Twin-Tube Road Tunnel

2022

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This study complements our previous work with a simultaneous analysis of user safety and road tunnel resilience. We developed a computational fluid dynamics (CFD) model and simulated the corresponding egress process to evaluate the risk level of users exposed to different types of fire, such those which might occur on the undisrupted lane of a partially closed tube tunnel due to a traffic accident, or in the adjacent tube when used for two-way traffic in the case of the complete closure of the tube involved in the accident. The CFD results showed that: (i) better environmental conditions were found with the partial closure of the tube rather than the complete one; (ii) additional benefits can be achieved by activating variable message signs (VMSs) that suggest an alternative itinerary for heavy good vehicles (HGVs) only; (iii) safety issues for human health may arise only in the case of a 100 MW fire, occurring during the complete closure of the tube and the use of the parallel one for two-way traffic. The findings of the CFD simulations were subsequently used to perform a quantitative risk analysis (QRA) based on a probabilistic approach. The findings of the QRA were found to be consistent with those obtained by the tunnel resilience analysis. In particular, the lowest risk level for user safety was found with the partial closure of the tube instead of the complete one, and by activating the VMSs to redirect HGVs only towards an alternative itinerary. This finding was found to correspond to a higher resilience index of the tunnel (i.e., a lower resilience loss due to a traffic accident occurring in a tube). This study increases our knowledge on certain relevant aspects of the operating conditions of tunnels and can serve as a possible reference for tunnel management agencies (TMAs) in their choice of the most appropriate arrangement to recover the functionality of a tunnel taking into account both user safety and resilience at the same time.

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“…Currently, gas-monitoring systems in underground mines are used successfully to predict the re-entry times after blasting operations [ 31 ]. CFD numerical simulations are also carried out for evaluating the risk level in road tunnels under fire scenarios while considering natural ventilation [ 32 , 33 ].…”

Section: Introductionmentioning

confidence: 99%

Concentration, Propagation and Dilution of Toxic Gases in Underground Excavations under Different Ventilation Modes

Menéndez¹,

Merlé

Oro

et al. 2022

IJERPH

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The drill-and-blast method is widely used for the excavation of hard rock tunnels. Toxic gases such as carbon monoxide and nitrogen oxides are released immediately after blasting by the detonation of explosives. To provide a safe working environment, the concentration of noxious gases must be reduced below the threshold limit value according to health and safety regulations. In this paper, one-dimensional mathematical models and three-dimensional CFD numerical simulations were conducted to analyze the concentration, propagation and dilution of the blasting fumes under different operating conditions. Forced, exhaust and mixed ventilation modes were compared to determine the safe re-entry times after blasting in a 200 m-long tunnel excavated using the top-heading-and-benching method. Based on the numerical simulations, carbon monoxide was the most critical gas, as it required a longer ventilation time to reduce its concentration below the threshold limit value. The safe re-entry time reached 480 s under the typical forced ventilation mode, but was reduced to 155 s when a mixed ventilation system was used after blasting, reducing the operating costs. The reduction of the re-entry time represents a significant improvement in the excavation cycle. In addition, the results obtained show that 1D models can be used to preliminary analyze the migration of toxic gases. However, to reliably determine the safe re-entry times, 3D numerical models should be developed. Finally, to verify the accuracy of the CFD results, field measurements were carried out in a railway tunnel using gas sensors. In general, good agreements were obtained between the 3D numerical simulations and the measured values.

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Risk Analysis of One-Way Road Tunnel Tube Used for Bi-Directional Traffic under Fire Scenarios

Cited by 8 publications

References 32 publications

A Numerical Study for Assessing the Risk Reduction Using an Emergency Vehicle Equipped with a Micronized Water System for Contrasting the Fire Growth Phase in Road Tunnels

A Numerical Study for Assessing the Risk Reduction Using an Emergency Vehicle Equipped with a Micronized Water System for Contrasting the Fire Growth Phase in Road Tunnels

A Simultaneous Analysis of the User Safety and Resilience of a Twin-Tube Road Tunnel

Concentration, Propagation and Dilution of Toxic Gases in Underground Excavations under Different Ventilation Modes

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