Road Tunnel Fire Research Articles

Discussing the Need to Manage Uncertainty Relating to Users in Road Tunnel Fire Risk Assessment

Although tunnels provide roads with numerous advantages, they also include significant risks. Especially, fire accidents are the biggest threats. Nowadays, risk assessment has the predominant role for managing tunnel fire safety and users are in the centre of attention. However, existing methods exhibit lack in treating uncertainty stemming from users. This paper aims to discuss current ways of representing tunnel users’ uncertainty as well as to introduce the importance of distinguishing these representations in the wider context of risk assessment.

Behaviors and Causal Explanations of Road-Tunnel Users During a Fire

The present study was aimed at describing the behaviors of tunnel users in the event of a road-tunnel fire,and to determine the effect of stress on these behaviors. Another aim was to identify the causal explanationsoffered by tunnel users for fires and for non-evacuation behaviors after a fire alarm is given. Several fire scenarioswere presented to 217 participants, who were asked to predict their likely behavior in the situations described,and to give explanations for the fire's occurrence. The participants' perceived stress level was also measured usinga subscale taken from the Depression Anxiety Stress Scales (DASS; Lovibond, & Lovibond, 1995). The resultsshowed that the participants tended to adopt more risky behaviors in situations where traffic was moving freelythan in congested traffic. The users' perceived stress led them to adopt unsafe behaviors, but contrary to Hennessyand Wiesenthal's (1997) results, this relationship was stronger in free-flowing traffic than in a traffic jam. Someof the participants demonstrated a certain behavioral rigidity, tending to adopt identical behaviors regardless ofthe traffic situation. The behaviors stated for a given situation seem to be consistent, but they were not alwayssafety-conscious. And the more serious the fire, the more internal the explanations were. Finally, non-evacuationbehaviors were attributed mainly to internal factors that implicated the concerned individuals. Some suggestionsfor long-term preventive actions based on users' beliefs and representations are proposed

Comparative Optimism, Perceived Control, Knowledge of Security Devices and the Behavior in Case of Road Tunnel Fire

This article presents a study aiming at investigating the effect of comparative optimism, anxiety, safety devices awareness on behavioural intention in case of a fire in a road tunnel. One hundred and fifty-one road users (firemen, truck drivers, regular drivers, and driving-school students) filled out a questionnaire measuring their perceptions of risks, their awareness of safety devices, and their behavioural intentions in case of a fire. Results show differences in perceptions between each category of participants and an interaction between anxiety and perceived control on comparative optimism. High professional practice with risk management lead to a better perception. For people with a low level of anxiety, comparative optimism is as high as perceived control is high. While for people with high level of anxiety, no variation was observed in comparative optimism according to the perceived control. We also found an effect of safety devices awareness on behavioural intentions. People with more rescue devices awareness tended to take less risk. Bearing on such results, suggestions are made for the improvement of communication in case of a fire and to develop users training in accordance with tunnel security specificities.

A numerical study on the influence of different tunnel lining insulation materials in a road tunnel fire

Various types of passive protection techniques have been investigated for road tunnels. A road tunnel fire is characterized by various parameters; one of the most important parameter is heat release rate (HRR). The heat release rate is considered a key parameter for design of various tunnel fire protection systems such as firefighting system, ventilation, and other passive protection systems. Many references are available from past researchers on heat release rates for different cases, where different type of vehicle/fuel was burned in a road tunnel. Later it was noticed that the heat release rate established by burning of vehicle/fuel in a tunnel gets modified by various other parameters. These parameters includes but not limited to fuel arrangements, tunnel ventilation, tunnel geometry, fixed firefighting system, fire growth rates etc. The passive fire protection systems are usually not considered as affecting heat release rates in tunnel. There is a need to better analyze this parameter in tunnel fires and to see their interaction with tunnel fire. A comparison of road tunnel with and without various passive protections under heavy good vehicle fire is studied by numerical modelling and presented under this study. This study shows tunnel protected with calcium silicate board results in higher temperature and heat fluxes compare to non-protected tunnel and tunnel protected with magnesium oxides/Cement based spray. This indicates that passive fire protection system can alter the thermal conditions inside the tunnel in case of fire.

Study on Underground Utility Tunnel Fire Characteristics under Sealing and Ventilation Conditions

With the development of the underground utility tunnel in China, the safety evaluation during facility operation inside tunnels is increasingly important after construction. In contrast to fixed fire source in the traffic tunnel, the fire characteristics of the electric cable compartment of the utility tunnel with different ventilation modes are studied. Firstly, the thermal physical parameters of cable material are determined by experiment and numerical simulation. Different fire sealing and ventilation conditions are established according to the practical utility tunnel engineering in FDS. The maximum temperature and smoke gas concentrations are obtained, as well as the heat release rate. The results show that the utility tunnel fire has obvious differences compared with road tunnel fire, where the maximum ceiling temperature and the distributions of smoke is related to fire sealing and ventilation mode. Some suggestions related to evaluation and firefighting are provided for practical purposes.

AHP and Casualties Calculation Based Research on Road Tunnel Fire Risk Evaluation

On the basis of classic risk theories this paper proposes a more pertinent and practical fire evaluation model for road tunnels. According to causes for tunnel fire, an index system for assessment of tunnel fire probability and rating criteria are established based on tunnel properties, environmental conditions, traffic status and vehicle performance. By fine modelling of tunnel fire smoke spread and personnel escape behaviour, a calculation method and rating criteria for consequences of tunnel fire are established. The research results suggest this method is a feasible means to assess road tunnel fire risks.

Study on the Standard of Fire Disaster Prevention for Super Large Cross Section Immersed Tunnels

Relying on the Shenzhen-Zhongshan subsea immersed tunnel project, combined the characteristics of highway tunnel traffic, the method of fire standard for super large cross section submarine immersed tunnel is proposed. Through the analysis of road tunnel fire cases, it is clear that vehicle spontaneous combustion is the main cause of tunnel fires. The ignition distance of different fire scales under the condition of tunnel traffic jam is determined by theoretical calculation. Through numerical simulation, when a super large cross section submarine immersed tunnel is fired under the condition of traffic jam, the scale of the fire is enlarged due to the ignition of the vehicle, and the fire scale design value of the super-large cross section submarine immersed tunnel is obtained. Based on the most dangerous situation of vehicle spontaneous combustion in an uni-direction four-lane tunnel, according to the actual traffic composition, the probabilistic method is used to analyze the composition of the laterally ignited vehicle and the probability of the event. It shows that the maximum probability of being ignited in a four-lane tunnel is one coach and one truck, and the fire prevention standard for Shenzhen-Zhongshan immersed tunnel is determined to be 50MW.

Quantitative Risk Assessment of Road Tunnel Fire Safety: Improved Evacuation Simulation Model

AbstractWith a view to enhance road network’s safety, it is crucial to focus primarily on its critical infrastructures, one part of which is tunnels. Fire safety of tunnels concerned intensely the ...

Numerical simulation of road tunnel fires involving heavy goods vehicle with solid fuels

The road tunnel fire is an emerging topic in literature and many key areas are still undiscovered. Road tunnel fires can be catastrophic and can result in a significant loss of human life and property. In literature various experimental and numerical studies are available on road tunnel fires. Most of these studies involved heavy goods vehicle with a combination of wooden/plastic pallets to represent fuel arrangement. The fire scenario of heavy goods vehicle with solid wooden/plastic fuel is not well studied. The burning behavior of pallets and solid blocks are different and hence the tunnel conditions would be different under fire in both these cases. This will result in a significant difference in key parameters such as heat release rates and temperature profiles inside the tunnel. To study these effects, full-scale fire tests are ideal and recommended, however, due to extremely high cost, downtime, and legal obligations it’s not always practical to conduct a full-scale fire test especially for road tunnels involving a heavy goods vehicle. In lieu of full-scale tests, numerical analyses are often used to understand these phenomena. This study focuses on studying the road tunnel fires involving heavy goods vehicle with solid fuels using CFD modelling in FDS (fire dynamic simulator). A pyrolysis model will be used to generate the anticipated heat in the tunnel. The kinetic properties of materials will be used in order to correctly calculate the pyrolysis rates of fuel. The findings of the heat release rate and lining temperature from the simulation will be compared with available results of heavy goods vehicle fires which involved pallets as fuel.

Investigation of road tunnel fires: challenges and findings

Numerical simulations have widely been used in the past to perform various complex engineering problems and phenomena. Most of the time the main objective of numerical modelling was to validate the outcome of experimental findings. However, it’s not always possible to replicate the exact conditions of experiments while doing a numerical simulation. There are various obstacles in modelling complex engineering problems such as the capability of a program, computational resources, time, understanding the real physics, modelling of components etc. This study will focus on the road tunnel fires with a heavy goods vehicle. A full-scale experiment of road tunnel fires is not always feasible because of very high cost and legal procedures. This motivates alternative techniques such as numerical modelling to study such phenomena. A numerical analysis of road tunnel fire involving heavy goods vehicle is undertaken in this study using FDS (Fire dynamic simulator) program. The study will discuss the challenges associated with the numerical modelling of road tunnel fires. A comprehensive summary of real problems encountered in such modelling, their possible causes, alternative ways, their impact of overall results and few solutions will be presented in this study. This paper reviews the similar work done by other researchers worldwide and provides a benchmarking.

Index Weight Determination for Road Tunnel Fire Risk Assessment Based on Fuzzy Analytic Hierarchy Process

Road tunnel, as an underground engineering, is characterized by unpredictability which has high fire risks in operation process. In recent years, major fire accidents have happened around the world in road tunnel operation process, causing enormous casualties and economic losses. Therefore, it is very necessary to assess fire risks during the road tunnel operation process. In this paper, an index system of road tunnel fire risk assessment with different categories of assessment indexes is established. Index weight is introduced to show the importance of each assessment index for assessment object. This paper adopts fuzzy analytic hierarchy process (FAHP) to express index weight with qualitative description language through pairwise comparison. Qualitative description language given by experts are indicated by correlative triangular membership function. Finally, through defuzzification and normalization, triangular fuzzy numbers are converted into final weights to establish the fire risk assessment index system during the road tunnel operation process.

Study on the smoke back‐layering and critical ventilation in the road tunnel fire at high altitude

SummaryA series of numerical simulations were conducted in order to investigate the characteristics of smoke back‐layering and critical ventilation in the road tunnel at high altitude with reduced ambient atmospheric pressures. The results indicated that the smoke back‐layering length decreases with the reduction of ambient pressure. Meanwhile, the dimensionless critical longitudinal ventilation velocity decreases with one‐third power of the factor of ambient pressure at high altitude. By modifying the traditional dimensionless fire heat release rate with ambient pressure, new models were deduced to predict the smoke back‐layering length and critical ventilation velocity in the road tunnel at high altitude.

Evaluating the role of risk assessment for road tunnel fire safety: A comparative review within the EU

Abstract Fire is the foremost critical event for road tunnels' safety. Therefore, the European Commission introduced the Directive 2004/54/EC for enhancing tunnels' safety since they constitute a key element of the Trans-European Road Network. The Directive has established a common ground for tunnels' safety evaluation providing certain minimum requirements while introducing officially the use of risk assessment. Despite the significant progress, this paper illustrates that further efforts are needed. Through a comparative review of the risk assessment methods, questions about the level of harmonisation of the framework are raised. Moreover, considerable problems are highlighted, like the incorporation of the new trends emerging from the literature or the deficiencies on addressing significant issues of the analysis, such as the risk acceptance criteria and the behaviour of trapped-users. These problems can affect the risk assessment process causing both significant discrepancies and deficiencies at the estimated level of tunnels' safety. Uncovering, thus, the deficiencies and limitations of the methods, this paper contributes to i) the discourse for initiating relevant studies to enhance tunnels’ fire safety in Europe and worldwide, and ii) the harmonisation of risk assessment methods.

Numerical study on overall smoke control using naturally ventilated shafts during fires in a road tunnel

This paper studies the overall smoke control of natural ventilation systems with vertical shafts during fires in a common road tunnel by numerical modelling. The variables studied include the heat release rate, longitudinal fire location along the tunnel, length of shafts and the interval between two shafts. Simulation results indicate that the total smoke spread length on both sides of fire source is closely independent of the heat release rate and longitudinal fire locations. For a given dimensionless shaft interval (the ratio of the shaft interval to shaft length), with the increase of shaft length, the smoke spread length firstly increases, reaching a maximum at 12 m, and then decreases significantly until 18 m. For a fire less than 30 MW, the first shaft pair on both sides of fire source prevents the critical-temperature smoke (270 °C) from spreading beyond this shaft. For a 100 MW fire, in the cases with shorter shaft lengths (Lshaft≤9 m), the critical-temperature smoke can't be controlled between the first shaft pair. The gas temperature at human height (1.8 m) is less than 60 °C in all cases with shafts. Downdraught occurs when the smoke front stabilizes at the bottom of a shaft and the buoyancy force could be too low to overcome the kinetic pressure of the air flow flowing into this shaft, consequently destroying the structure of smoke layer. In most scenarios, the total exhaust area of shafts that is required to exhaust all the smoke is about 100 m2. The first shaft pair plays a critical role to exhaust the smoke, and its exhaust efficiency is also affected significantly by the shaft length. This study investigates how to control the smoke by using vertical shafts in a road tunnel fire and the conclusions are useful to tunnel fire protection engineering.

Effect of Re-ventilated Fan Capacity on Road Tunnel Fire

Effect of Re-ventilated Fan Capacity on Road Tunnel Fire

Validation of 3D Fire Simulator FDS for evaluation of ventilation control and water spray activation at road tunnel fires with risk analysis model

Validation of 3D Fire Simulator FDS for evaluation of ventilation control and water spray activation at road tunnel fires with risk analysis model

Road tunnel fire safety assessment

Road tunnel fire safety assessment

Possibility of the Early Detection of Road Tunnel Fire

Possibility of the Early Detection of Road Tunnel Fire

Note on the impact of slope on smoke spread in tunnel fire conditions

Fires in road tunnels produce a large amount of smoke threatening passengers´ lives and health and tunnel facilities. The spread of fire smoke is influenced by various factors. In this paper, the Fire Dynamics Simulator system is used to study the spread of smoke produced by fires with various heat release rates in two 900 m long tunnels which differ from each other by slope. The impact of slope on smoke backlayering and smoke spread in tunnel tube is illustrated. The simulation results show that buoyant forces induced by fire accelerate the smoke spread in ascending sections and slow the smoke spread in descending sections of the tunnel. The analysis indicates that the tunnel slope can have significant impact on smoke spread in road tunnels.

Determination of critical parameters in the analysis of road tunnel fires

The analysis of the fluid characteristics downstream of a fire source in transportation tunnels is one the most important factor in the emergency response, evacuation, and the rescue service studies. Some crucial parameters can affect the fluid characteristics downstream of the fire. This research develops a statistical analysis on the computational fluid dynamics (CFD) data of the road tunnel fire simulations in order to quantify the significance of tunnel dimensions, inlet air velocity, heat release rate, and the physical fire size (fire perimeter) on the fluid characteristics downstream of the fire source. The selected characteristics of the fluid (response variables) were the average temperature, the average density, the average viscosity, and the average velocity. The prediction of the designed statistical models was assessed; then the significant parameters’ effects and the parameters interactive effects on different response variables were determined individually. Next, the effect of computational domain length on the selection of the significant parameters downstream of the fire source was analyzed. In this statistical analysis, the linear models were found to provide the statistically good prediction. The effect of the fire perimeter and the parameters interactive effects on the selected response variables downstream of the fire, were found to be insignificant.