Civil engineering comprises the planning, risk-assessment, design, construction, and maintenance of buildings, services, and towns. The subjects covered in this book include roads, railways, bridges and tunnels; houses and halls with load-bearing structures and facades; services: heating, lighting, acoustics and fire safety; water supply, drains and sewers; canals, harbours and offshore structures; and town plans.
The Tunnel Engineering Handbook, Second Edition provides, in a single convenient volume, comprehensive coverage of the state of the art in the design, construction, and rehabilitation of tunnels.
It brings together essential information on all the principal classifications of tunnels, including soft ground, hard rock, immersed tube and cut-and-cover, with comparisons of their relative advantages and suitability.
The broad coverage found in the Tunnel Engineering Handbook enables engineers to address such critical questions as how tunnels are planned and laid out, how the design of tunnels depends on site and ground conditions, and which types of tunnels and construction methods are best suited to different conditions. In addition, the book contains a wealth of information that government administrators and planners and transportation officials will use in the planning and management of tunnels.
Richard Carvel , Alan Beard. A history of experimental tunnel fires. Fire dynamics in tunnels. Haukur Ingason. CFD modelling of tunnel fires. Norman Rhodes. Control volume modelling of tunnel fires.
David Charters. Problems with using models for fire safety. Human behaviour in tunnel fires. Jim Shields. Recommended behaviour for road tunnel users. Michel Egger. Transport of hazardous goods. Tunnel ventilation: state of the art. Art Bendelius. The use of tunnel ventilation for fire safety. George Grant , Stuart Jagger.
The influence of tunnel ventilation on fire behaviour. Richard Carvel , Alan Beard. A history of experimental tunnel fires. Fire dynamics in tunnels. Haukur Ingason. Heat release rates in tunnel fires: a summary. CFD modelling of tunnel fires. Norman Rhodes. Control volume modelling of tunnel fires. David Charters. One-dimensional and multi-scale modelling of tunnel ventilation and fires.
Non-deterministic modelling and tunnel fires. Alan Beard. Human behaviour during tunnel fires. The question is not so much how can a risk-based approach replace a prescriptive approach?
Both prescriptive and risk-based. Conversely, while a risk-based approach does, in principle, allow us to appreciate what the risk is, there are considerable problems associated with assessing risk and being able to use that modelling as part of tunnel re safety decision-making in an eective and acceptable way.
The issue relates to knowing what methodology to adopt when applying a risk-based approach. Methodologies range from a very hard methodology, in which there is overwhelming agreement among the actors or participants as to what the problem is and what is desirable, through to soft systems methodologies. In a purely hard methodology there is considerable knowledge and understanding of the system, very little uncertainty and no iteration in the decision-making process.
The method proceeds from problem to solution in a mechanical orderly manner; see, for example, Reference 1.
While such an approach may be suitable for some situations, e. At the other end of the spectrum are the soft systems methodologies, for example the one by Checkland.
There will usually be considerable uncertainty and may be dierences of opinion as to what the problem actually is. Classic soft systems problems are those associated with, say, healthcare.
Between the hard and soft ends of the spectrum of methodologies are the intermediate methodologies. It is likely that an intermediate methodology would be appropriate for decision-making with respect to tunnel re safety. A methodology which is intermediate but lies towards the hard end of the spectrum is the one outlined by Charters3 in Figure 0. While this contains an iteration loop one characteristic of an intermediate methodology , the degree to which it is hard or not depends upon how much time and eort is put into each of the stages, for example the stage aimed at deciding whether or not the risk implicit in an option is acceptable.
Another intermediate methodology is that constructed by the current author,4;5 an amended version of which is shown in Figure 0. This spends much more time in the earlier stages and includes an iteration loop after every stage. There is also an emphasis on learning from near misses.
Near misses represent a very great source of information and knowledge about the behaviour of real-world systems and we should tap this source much more than we do at the present time. While this methodology is intermediate it leans more towards the softer end of the spectrum than does the methodology described by Charters.
Having decided on an overall methodology, with a risk-based approach it becomes necessary to construct models in relation to tunnel res and the models constructed become ever more complex. There are fundamental problems associated with constructing and using models in a reliable and acceptable way.
Every quantitative model makes conceptual assumptions and these may be inadequate. There may be, for example, possible real-world sequences which we simply do not know about and which, therefore, have not been considered in an analysis at all; this would be in addition to possibly unrealistic assumptions about sequences which have been included in an analysis.
For example, a sequence involving a heavy goods vehicle HGV on re may be included in an analysis but the assumptions about re development and. Figure 0. Considerations of this kind have been discussed further in reference. These diculties mean that, even if a model has the potential to be valuable, acceptable use of a model is generally very problematic and requires a knowledgeable user employing an acceptable approach.
As a general rule the conditions do not yet exist for reliable and acceptable use of complex computer-based models as part of tunnel re safety decision-making. These conditions need to be created. Some basic issues, in no particular order of importance, which exist in relation to tunnel re safety and which we need to be able to cope with are given below; there is no doubt that there are many others.
Fire risk in tunnels is a result of the working of a system involving design, operation, emergency response and tunnel use. That is, re risk is a systemic product. Further, this tunnel system involves both designed parts and non-designed parts, for example trac volume or individual behaviour of users. The designed parts need to take account of the non-designed parts as much as possible. Tunnels are becoming ever larger and more complex; we need to be able to deal with this. The system changes.
A tunnel system which exists at the time of opening will be dierent to the tunnel system which exists a few years later. As a corollary: what are to be regarded as acceptable ranges for an upgraded existing tunnel as opposed to a new tunnel?
What is to be an acceptable methodology for tunnel re safety decision-making? The part played by models in tunnel re safety decision-making.
Models, especially computer-based models, have the potential to play a very valuable role. However, an acceptable context within which models may be employed in a reliable and acceptable way needs to be created. This implies: 1 independent assessment of models, their limitations and conditions of applicability; 2 acceptable methodologies of use for models given cases; 3 knowledgeable users who are familiar both with the.
Models should only ever be used in a supportive role, in the context of other re knowledge and experience. An overarching probabilistic framework needs to be created, within which both probabilistic and deterministic models may play a part. A synthesis of deterministic and probabilistic modelling needs to be brought about. Experimental tests: we need large and full-scale tests as well as small-scale tests.
Also, we need replication of experimental tests, because of the variability of experimental results for ostensibly identical tests. Operator response: 1 to what extent is automation feasible or desirable? Tunnel re dynamics: we know more than we did but we need to know much more.
Fire suppression: what kinds of systems are appropriate? How is real human behaviour to be taken account of in tunnel re emergencies? At present we know very little. Whatever else follows from considering the above issues, one thing is certain: a sound understanding of tunnel re science and engineering is needed. Further, this needs to be seen in its widest sense to include, for example, human behaviour and what risk is to be regarded as socially acceptable.
While a signicant amount of tunnel re research has been carried out in recent years, much remains to be done. Moreover, as systems change then there will be a continual need for re research to understand the nature of re risk in tunnels and be able to control it in an acceptable way.
Needed research is implied by the issues raised above. More specically, to pinpoint a very few, some key research questions which we need answers to are: a b c d What are eective ways of preventing res occurring in tunnels?
What are the factors aecting tunnel re size and spread? What are the characteristics of dierent tunnel re suppression systems?
Other issues and needed research areas are implied in the chapters of this Handbook and especially in the chapter on Tunnel re safety and the law by Arnold Dix Chapter Addressing the research required as a result of considering the above issues and key research questions will require willingness by researchers to become engaged in such areas and also funding.
International collaboration in research has played an important role in the past and it may be expected to continue to do so. There needs to be a strategy for tunnel re research, involving both international collaboration and eort by individual countries. Further, there needs to be an openness about research results. It is not acceptable for results to be kept secret. However it is done, these issues and implied research areas need to be addressed for the benet of all countries and their citizens.
References 1. The Hard Systems Approach. Checkland, P. Systems Thinking, Systems Practice. Wiley, Chichester, Charters, D. Fire risk assessment of rail tunnels. Beard, A. Towards a rational approach to re safety. Fire Prevention Science and Technology, , 22, Towards a systemic approach to re safety. Risk assessment assumptions. Civil Engineering and Environmental Systems, , 21 1 , Introduction Websters dictionary denes ventilation simply as circulation of air.
Ventilation does not necessarily mean the use of mechanical devices such as fans being employed; the non-fan or natural ventilation is still considered to be ventilation. From that simple denition of ventilation we move forward to the ventilation of tunnels. The use of tunnels dates back to early civilisations and so too does ventilation in the form of natural ventilation. However, the ventilation of tunnels has taken on greater signicance within the past century, due to the invention and application of steam engines and internal combustion engines which are prevalent as motive power in the transport industry.
This all became evident as increasing quantities of combustion products and heat would become more troublesome to the travelling public. Exposure to the products of combustion generated by vehicles travelling through a tunnel can cause discomfort and illness to vehicle occupants. Ventilation became the solution by providing a means to dilute the contaminants and to provide a respirable environment for the vehicle occupants.
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