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Fire safety design of road tunnels

Gehandler, Jonatan LU (2020) Report 1059.
Abstract
This thesis can be described as a journey in performance-based fire safety design. Along the way questions such as what fire safety is, how it can be measured, whether we are posing the right questions, or engineer the best solutions, have arisen. The safety journey naturally started out with the traditional view, with fire safety engineering based on limit-based design. Using this paradigm the safety problem is limited to fire safety issues, and safety levels are defined for each fire safety objective in isolation. This contradicts the basic rationale of decision-making where the best trade-off is sought between all objectives, most often by use of Cost-Benefit Analysis (CBA). This naturally led to the second stop of the safety journey... (More)
This thesis can be described as a journey in performance-based fire safety design. Along the way questions such as what fire safety is, how it can be measured, whether we are posing the right questions, or engineer the best solutions, have arisen. The safety journey naturally started out with the traditional view, with fire safety engineering based on limit-based design. Using this paradigm the safety problem is limited to fire safety issues, and safety levels are defined for each fire safety objective in isolation. This contradicts the basic rationale of decision-making where the best trade-off is sought between all objectives, most often by use of Cost-Benefit Analysis (CBA). This naturally led to the second stop of the safety journey called CBA-based design where risk is exchanged as a cost factor in a cost-benefit framework. In this paradigm safety is a relative concept depending also on a few other measurable objectives. Throughout this work, the focus of the journey has been on road tunnels. Tunnels are hard physical and technical systems. However, they exist in a social reality and a complex society. During the design process many social and soft issues surface that can conflict with technical fire safety measures. The journey thus went on to acknowledge both the scientific or technical aspects of risk and social structures; the ethical and democratic aspects of risk, in a decision-making framework. This emphasizes how the problem is framed, what our objectives are, and how creative alternatives are generated and assessed. It may not even be relevant to talk about "how safe should the tunnel be" because it is subordinate to the overall decision condition, all aspects considered. In the end a design alternative is chosen that exhibit the highest utility on all objectives together, i.e. safety in balance with other objectives. For any tentative design, safety can develop in two directions; Firstly, it may be that some safety measures are too conservative or in conflict with other objectives such as cost or the environment, i.e. resources are better used elsewhere. Secondly, it may also be possible to achieve more safety; it is argued that a Vision Zero design philosophy with its emphasis on inherently safer or fail-safe systems highlight important safety qualities which are not highlighted in limit-based or CBA-based design. Along the way (a) road tunnel fire safety and risk literature were studied, (b) interviews were made with tunnel fire safety professionals (c) performance based requirements for road tunnel fire safety were derived, (d) the accuracy of tunnel fire dynamics models applied in road tunnel fire risk analysis was compared with experimental data, and (e) the design framework of fire safety engineering was critically analyzed and an alternative fire safety design framework was proposed. (Less)
Abstract (Swedish)
Det ökande byggandet av stadsvägtunnlar, de alpina tunnelolyckorna runt millennieskiftet, och det efterföljande EU-direktiv (2004/54/EC) med minimikrav gällande brandsäkerhet har placerat brandsäkerhet i vägtunnlar högt på dagordningen. Samtidigt är moderna enkelriktade vägtunnlar ofta bland de säkraste delarna av vägsystemet. Har vi kommit till en punkt där resurserna används bättre någon annanstans? Detta leder till en central fråga i denna avhandling: hur säkert är tillräckligt säkert? Längs vägen visade det sig vara en mycket utmanande och spännande fråga. I litteraturen framträder den i olika formuleringar och därmed olika logiska svar. Längs vägen har frågor som, hur brandsäkerhet kan mätas, om vi ställer rätt frågor eller skapar de... (More)
Det ökande byggandet av stadsvägtunnlar, de alpina tunnelolyckorna runt millennieskiftet, och det efterföljande EU-direktiv (2004/54/EC) med minimikrav gällande brandsäkerhet har placerat brandsäkerhet i vägtunnlar högt på dagordningen. Samtidigt är moderna enkelriktade vägtunnlar ofta bland de säkraste delarna av vägsystemet. Har vi kommit till en punkt där resurserna används bättre någon annanstans? Detta leder till en central fråga i denna avhandling: hur säkert är tillräckligt säkert? Längs vägen visade det sig vara en mycket utmanande och spännande fråga. I litteraturen framträder den i olika formuleringar och därmed olika logiska svar. Längs vägen har frågor som, hur brandsäkerhet kan mätas, om vi ställer rätt frågor eller skapar de bästa lösningarna, uppstått. Under hela detta arbete har fokus varit på vägtunnlar.
Ingenjörsvetenskapen dominerar designen av brandsäkerhet idag vilket ger en matematiskt fokuserad process med fokus på att verifiera relativt godtyckliga kvantitativa mål som anses representera en acceptabel säkerhet. Tunnlar är hårda fysiska och tekniska system. De finns dock i en social verklighet och i ett komplext samhälle. Flera faktorer har identifierats som påverkar säkerheten i en tunnel. Brandsäkerhet kan främja eller stå i konflikt med miljöaspekter, till exempel utsläpp av växthusgaser. Med ett rättviseperspektiv bör vi prioritera mer sårbara och riskutsatta trafikanter på trottoarer och övergångsställen ovan mark. En god upplevd säkerhet när man kör genom en tunnel gynnar människors frihet samtidigt som det leder till mindre stress och olyckor. Andra mål som vi värnar om såsom kostnad, miljö och rättvisa finns naturligt med som en del i vägprocessen genom miljöbalken men passar inte in i dagens designprocess av brandsäkerhet. Det upplevs som ”svårt” att väga brandsäkerhet mot andra mål. Istället blir principer såsom undvikande av katastrofer och ständig förbättring dimensionerande för brandsäkerheten. Det är dock inte nödvändigtvis rimligt att brandsäkerhet i tunnlar ständigt ska förbättras, givet begränsade resurser och andra akuta risker såsom klimathotet, som dessutom kan stå i konflikt med en ökad brandsäkerhet.
Någon mekanism krävs som ger en balanserad avvägning utifrån dagens samhälle och värld. En probleminramning förespråkas som erkänner både de tekniska aspekterna av risker och de etiska och demokratiska aspekterna av risker. Genom att använda en generell beslutsmetod inkluderas viktiga steg i beslutsprocessen såsom hur problemet ramas in, vilka mål som sätts upp, och hur kreativa alternativ kan genereras och värderas. Grundtanken inom beslutsteori är att välja den lösning och kompromiss som sammantaget bäst uppfyller målen. Målen och prioriteringen av dem bestäms av byggherren och förvaltaren, ofta Trafikverket, i samråd med andra berörda aktörer och bör svara mot samhällets värderingar. Enbart genom att beakta alla delar av beslutsprocessen går det att argumentera för att det bästa beslutet har fattats.
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Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Dr Meacham, Brian J., Meacham Associates, USA
organization
publishing date
type
Thesis
publication status
published
subject
keywords
Brandsäkerhet, vägtunnlar, design, Riskbedömning, Road tunnel fire safety, Fire safety engineering, design framework, risk evaluation
volume
Report 1059
pages
91 pages
publisher
Lund University. Department of Fire Safety Engineering
defense location
Lecture Hall V:D, V-Building, John Ericssons väg 1, Lund University, Faculty of Engineering LTH
defense date
2020-02-06 13:00:00
ISBN
978-91-7895-345-5
978-91-7895-344-8
language
English
LU publication?
yes
id
7abf687e-c873-4d0d-ae44-cd45809284c5
date added to LUP
2019-12-10 09:21:58
date last changed
2020-01-09 13:27:25
@phdthesis{7abf687e-c873-4d0d-ae44-cd45809284c5,
  abstract     = {This thesis can be described as a journey in performance-based fire safety design. Along the way questions such as what fire safety is, how it can be measured, whether we are posing the right questions, or engineer the best solutions, have arisen. The safety journey naturally started out with the traditional view, with fire safety engineering based on limit-based design. Using this paradigm the safety problem is limited to fire safety issues, and safety levels are defined for each fire safety objective in isolation. This contradicts the basic rationale of decision-making where the best trade-off is sought between all objectives, most often by use of Cost-Benefit Analysis (CBA). This naturally led to the second stop of the safety journey called CBA-based design where risk is exchanged as a cost factor in a cost-benefit framework. In this paradigm safety is a relative concept depending also on a few other measurable objectives. Throughout this work, the focus of the journey has been on road tunnels. Tunnels are hard physical and technical systems. However, they exist in a social reality and a complex society. During the design process many social and soft issues surface that can conflict with technical fire safety measures. The journey thus went on to acknowledge both the scientific or technical aspects of risk and social structures; the ethical and democratic aspects of risk, in a decision-making framework. This emphasizes how the problem is framed, what our objectives are, and how creative alternatives are generated and  assessed. It may not even be relevant to talk about "how safe should the tunnel be" because it is subordinate to the overall decision condition, all aspects considered. In the end a design alternative is chosen that exhibit the highest utility on all objectives together, i.e. safety in balance with other objectives. For any tentative design, safety can develop in two directions; Firstly, it may be that some safety measures are too conservative or in conflict with other objectives such as cost or the environment, i.e. resources are better used elsewhere. Secondly, it may also be possible to achieve more safety; it is argued that a Vision Zero design philosophy with its emphasis on inherently safer or fail-safe systems highlight important safety qualities which are not highlighted in limit-based or CBA-based design. Along the way (a) road tunnel fire safety and risk literature were studied, (b) interviews were made with tunnel fire safety professionals (c) performance based requirements for road tunnel fire safety were derived, (d) the accuracy of tunnel fire dynamics models applied in road tunnel fire risk analysis was compared with experimental data, and (e) the design framework of fire safety engineering was critically analyzed and an alternative fire safety design framework was proposed.},
  author       = {Gehandler, Jonatan},
  isbn         = {978-91-7895-345-5},
  language     = {eng},
  month        = {02},
  publisher    = {Lund University. Department of Fire Safety Engineering},
  school       = {Lund University},
  title        = {Fire safety design of road tunnels},
  url          = {https://lup.lub.lu.se/search/ws/files/72981290/Jonatan_Gehandler_web.pdf},
  volume       = {Report 1059},
  year         = {2020},
}