The international FORUM of fire research directors: A position paper on future actions for improving road tunnel fire safety

Fire safety in tunnels has come in focus owing to numerous catastrophic fires and extensive monitoring in media. Casualties can be counted in hundreds and the economic damages have been enormous not only for tunnel owners but also for users and bordering communities. The recent increase in serious road tunnel fires is closely associated with the increase in the traffic volume as well as in the large number of tunnels being built in recent years. In particular, volumes transported on heavy goods vehicles have increased by 40–80% over a decade in many European countries. Today, about 75% of all goods traffic is by road, and is expected to increase by 40–60% over the next 10 years [Thamm B. The new EU directive on road tunnel safety. In: Proceedings of the international symposium on catastrophic tunnel fires (CTF), SP Swedish National Testing and Research Institute, SP Report 2004:05. p. 19–30].This FORUM position paper discusses some aspects on how to improve the design of road tunnels in order to obtain a higher level of fire safety. It discusses briefly design principles of tunnels as well as of fire safety of vehicles, use of forced ventilation systems and of active fire suppression.     

隧道结构防火研究综述

随着我国交通隧道建设的飞速发展,隧道的消防安全问题也随之而来,并且受到越来越多的关注;结合国内外近年来在隧道结构被动防火方面的研究进展,总结了隧道火灾的危害性和特点,以及提高隧道衬砌结构耐火性能的措施,为保障隧道的消防安全提供一些参考,并对需进一步深入研究的问题提出建议。     

越江隧道的性能化消防安全设计对策

介绍了上海公路越江隧道的现状和发展趋势，分析了公路越江隧道潜在的火灾危险性和危害性，并从结构防火保护、火灾自动报警、自动喷水灭火、通风排烟和安全疏散等方面提出了公路越江隧道性能化消防设计的对策及建议。     

电力隧道消防设计思考

通过对220kV4回路电力隧道消防系统设计的探讨,系统地阐述了电力隧道消防系统设计的三个部分及应注意的一些问题,从而使电力隧道消防设计更加完善,确保电力隧道消防安全。     

Heat Release Rate of Heavy Goods Vehicle Fire in Tunnels with Fixed Water Based Fire-Fighting System

A series of large-scale fire tests for road tunnel application was conducted in a test tunnel facility in Spain. The aim of this fire tests program was to investigate the magnitude of the heat release rate generated by a fire in heavy goods vehicles (HGV’s) with and without a fire suppression system in tunnels in Singapore; the possibility of interchanging a fire suppression system with other measures such as lowering the longitudinal flow velocity; and to acquire information on the appropriate design parameters (e.g., nozzle type, discharge density and activation time) to adopt based on the most probable fuel load used in these road tunnels. In order to ensure repeatability, simulated HGV’s consisting of 228 pallets with 48 plastic pallets (20%) and 180 wooden pallets (80%) were used in all fire tests. An air velocity of approximately 3 m/s was applied. As the scope of work covered in this fire test program is very large, only the setup of the fire test and the findings on the effects of heat release rate with (Test 4) and without (Test 7) a fixed water based fire-fighting system are covered. The test results indicate that a substantial reduction of fire heat release rate can be obtained using a low-pressure deluge fire suppression system, as long as timely activation of the water is provided. However, the influence of the suppression system on CO production is significant. Such experimental data address the current dearth of knowledge on the actual effect of low-pressure deluge systems on the heat release rate from HGVs in tunnel fires.     

Fixed Fire Protection Systems in Tunnels: Issues and Directions

Fire protection practices for highway tunnels have been undergoing significant changes in the last decade, largely in response to a number of catastrophic fires that caused tunnel authorities to thoroughly review their fire safety assumptions. One of the fire safety issues currently receiving much attention includes the installation of “active” fire protection systems in addition to the “passive” fire protection features that were until recently considered to be sufficient to mitigate fire risk in tunnels. Passive fire protection measures include the use of fire resistive construction materials which help protect the critical structural elements from damage due to high temperatures. Active fire protection systems include fixed piping systems to deliver water sprays, such as deluge sprinklers and water mist, or other water-based agents such as compressed air or high expansion foam (CAF or Hi-Ex respectively). Active fire protection systems for tunnels are currently referred to as water based fixed fire fighting systems, or FFFS for short. Fire research suggests that measures based solely on passive protection are not likely to be sufficient to protect life and property to the degree warranted by the high monetary and strategic value of modern tunnel infrastructure. Full-scale fire testing and engineering analysis indicate that FFFS have the potential to reduce the impact of a severe fire on the tunnel structure from catastrophic to manageable at an affordable cost. Fire testing with CAF and Hi-Ex foam systems has shown them capable of actually extinguishing very large fires, including hydrocarbon pool fires. Systems based on water sprays on the other hand are not expected to extinguish fires, but rather to control the fire, limit fire growth and heat release rate, prevent fire propagation and provide thermal management. Although there are a few years of experience internationally that have proven sprinkler and deluge sprinkler system to be effective in mitigating tunnel fires, recent testing of FFFS in Europe has concentrated on water mist. One reason is the perception that water mist systems may involve less complex piping and agent storage than CAF or Hi-Ex foam, and may provide equivalent or superior performance with less water and smaller pipes than conventional sprinkler deluge systems. However, many engineering challenges remain to be resolved, such as how much credit to grant to the FFFS in terms of reduced criteria for passive protection, and how exactly to integrate active protection systems with traditional fire safety measures such as the ventilation systems. This article examines some recent developments in understanding how active fire-fighting systems might alter the impact of fires in tunnels.     

Findings of the International Road Tunnel Fire Detection Research Project

Fire detection systems are essential fire protection elements for road tunnels to detect fires, activate safety systems and direct evacuation and firefighting. However, information on the performance of these systems is limited and guidelines for application of tunnel fire detection systems are not fully developed. The National Research Council of Canada and the Fire Protection Research Foundation, with support of government organizations, industries and private sector organizations, have completed a research project to investigate current fire detection technologies for road tunnel protection. The project included studies on the detection performance of current fire detection technologies with both laboratory and field fire tests combined with computer modelling studies. This paper provides an overview of the findings of the project. Fire detectors, fire scenarios and test protocols used in the test program are described. A summary of the research results of the series of full-scale fire tests conducted in a laboratory tunnel facility and in an operating road tunnel as well as of the computer modelling activities will be reported.     

Study of smoke backlayering during suppression in tunnels

Full-scale suppression tests and Computational Fluid Dynamics (CFD) simulations were carried out to investigate the effect of Water-based Fixed Fire Fighting Systems (WFFFS) on the effectiveness of longitudinal ventilation systems in resisting smoke backlayering in tunnels. Test results show that WFFFS enables longitudinal ventilation systems to resist smoke backlayering with a lower velocity than the critical velocity for the same size of tunnel fire. Based on data obtained from the test program and the simulation program, a design method is proposed to estimate the velocity required to resist smoke backlayering in tunnels when WFFFS is active.     

谈城市隧道给排水及消防系统设计方案

主要对城市隧道排水系统、消防给水系统及自动报警系统如何合理设计进行了分析和探讨,提出了包括隧道口设横向截水沟与隧道内设纵向排水沟、隧道内设环状消火栓供水系统与水成膜泡沫灭火装置设计方案,以期保证城市隧道建设顺利进行。     

Findings of the International Road Tunnel Fire Detection Research Project

Fire detection systems play a crucial role in ensuring safe evacuation and firefighting operations in road tunnels, but information on the performance of these systems in tunnels has been limited and guidelines for their application in tunnel environments are not fully developed. Recently, the National Research Council of Canada (NRC) and the Fire Protection Research Foundation completed a 2-year international research project, with the support of private- and public-sector organizations, to determine some of the strengths and weaknesses of the various types of fire detection systems and the factors that can affect their performance in tunnel environments. The project included both laboratory and field fire tests combined with computer modeling studies. Although this research was conducted on road tunnels, the findings should apply to other tunnels, such as those used in subway systems. As part of the project, the NRC conducted two series of tests in the Carleton University-NRC tunnel facility to investigate the performance of detection systems under minimal and longitudinal airflow conditions. In addition, NRC conducted tests in the Carré-Viger Tunnel in Montréal, as well as a computer modeling study. The project studied nine fire detection systems that covered five types of currently available technologies. The performance of the detection systems, including response times and ability to locate and monitor a fire in the tunnel and the effect of the tunnel environment, were evaluated under the same conditions. This article provides an overview of the findings of the project. Fire detectors, fire scenarios and test protocols used in the test program are described. A summary of the research results of the full-scale fire tests conducted in a laboratory tunnel facility and in an operating road tunnel as well as of the computer modeling activities is reported.     

A Comparison of a Statistical and Computational Fluid Dynamics Approach to Estimate Heat Release Rate in Road Tunnel Fires

Computational tools such as one-dimensional models or Computational Fluid Dynamics (CFD) have been used for the fire safety design of road tunnels. However, most of these analyses are performed using a specified fire source where the heat release rate (HRR) in the tunnel is fixed by the user and the influences of ventilation conditions and tunnel geometry are not considered. For a more realistic estimate, models need to incorporate these factors in their input. This paper discusses the use of a statistical approach previously developed by other researchers (Carvel and Beard, The handbook of tunnel fire safety. Thomas Telford Publishing, pp 184–197, 2005) and the use of a CFD approach to estimate the HRR in a road tunnel fire. As an application example, fire scenarios in which a light goods vehicle carrying wooden pallets are used to compare the estimation of the HRR using these two methods.     

Smoke control in sloping tunnels

The critical velocity to prevent upstream smoke flow in the event of a tunnel fire is an important part of the design of emergency ventilation systems. For tunnels with a downhill slope the critical velocity is somewhat greater than for the corresponding horizontal tunnel. This note presents experimental results from a study involving model tunnels with slopes between 0 and 10 degrees. A general slope correction factor is derived from these results.     

Experimental evaluation of the fire behaviour of insulated fibre-reinforced-polymer-strengthened reinforced concrete columns

In recent years, there has been an increase in the use of fibre reinforced polymer (FRP) materials for strengthening of concrete structures. However, since FRP materials are combustible, and because they are typically applied to the exterior of structural members in these strengthening applications, concerns exist regarding the behaviour of such FRP strengthening systems in fire. There is currently little information available on the fire endurance of FRP-strengthened concrete systems. This paper presents results from full-scale fire resistance experiments on three insulated FRP-strengthened reinforced concrete (RC) columns. A comparison is made between the fire performances of FRP-strengthened RC columns and conventional unstrengthened RC columns tested previously. Data obtained during the experiments is used to show that the fire behaviour of FRP-wrapped concrete columns incorporating appropriate fire protection systems is as good as that of unstrengthened RC columns. Thus, satisfactory fire resistance ratings for FRP-wrapped concrete columns can be obtained by properly incorporating appropriate fire protection measures into the overall FRP-strengthened structural system. Fire endurance criteria and preliminary design recommendations for fire safety of FRP-strengthened RC columns are briefly discussed.     

关注隧道消防构筑和谐工程--关于公路隧道消防安全工作的探讨与思考

从介绍云南公路隧道的情况入手，引用国内外公路隧道火灾的典型案例，通过纵横比较和分析，探讨研究了公路隧道消防安全工作面临的形势和问题，并提出了防范措施与处置对策。     

城市水下长隧道的消防水系统设计探讨

根据城市水下长隧道火灾的特点及其危险性,对消防水系统设置及其应考虑的主要因素等问题进行探讨,并针对中国城市穿越江、河隧道的消防水系统设置无明确规定的现状,参考多个隧道设计实例,提出目前隧道消防水系统设计中存在的不足,为今后进一步提高隧道内消防能力,进行水下长隧道消防水系统设计提供参考依据。     

高海拔单洞+服务隧道横通道间距设置研究

以火灾工况下人员安全疏散作为控制标准,同时考虑高海拔对烟雾扩散以及人员逃生速度、心理等因素的影响,建立随机停车最不利工况下火灾计算模型以及人员逃生计算模型,分别计算人员逃生可用安全疏散时间及必需安全疏散时间,研究海拔超过3 500 m单洞+服务隧道满足乘车人员全部安全逃生的最佳横通道间距。计算结果表明:在高海拔地区隧道内列车发生火灾且随机停车模式下,将计算所得人员逃生可用时间与人员逃生必需时间进行对比,为保证人员疏散安全,此类铁路隧道横通道间距应250 m设置一道。计算结果可为类似高海拔隧道横通道间距设计提供参考。     

The fire catastrophe in the Tauern Tunnel: experience and conclusions for the Austrian guidelines

A fire occurred in the Tauern Tunnel, Austria on 29 May 1999 and caused severe casualties and damage. This paper examines the damage in the tunnel and the remedial work carried out — with a particular emphasis on the additional safety equipment required in the tunnel. The Austrian guidelines for tunnel construction have been subsequently revised to improve the fire safety in tunnels.     

隧道式建筑火灾的消防对策

Tunnel is type of long and narrow underground building. Common tunnels are city metro tunnel, railway tunnel and motorway tunnel. These tunnels are for the commuting of vehicles. Some go through mountains, others go under the sea and many are over thousands meters long. In recent years, there have beeu many tunnel fires home and abroad. Based on the theory el tunnel fire smoke movement, the arlicle analyzes the features el tunnel fire and proposes directional lirelightiflg schemes in tunnel fire design.     

特长铁路隧道横通道间距设置问题研究

铁路隧道的横通道作为灾害发生后的安全疏散通道,其间距的设置在人员安全疏散中是至关重要的。本文以特长铁路隧道为研究对象,从人员安全疏散的角度出发,运用疏散模拟软件STEPS建立人员安全疏散计算数学模型,模拟计算了两种火灾场景在不同横通道间距情况下人员疏散所必需时间,通过与人员安全疏散可利用时间比较,判断人员疏散的安全性,给出了一般特长铁路隧道横通道间距设置方案,为特长铁路隧道安全疏散设施的优化设计提供理论依据。