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Model scale fire tests were performed in tunnels with varying tunnel widths and heights in order to study the effect of tunnel cross-section and ventilation velocity on the heat release rate (HRR) for both liquid pool fires and solid fuel fires. The results showed that for well ventilated heptane pool fires, the tunnel width nearly has no influence on the HRR whilst a lower tunnel height clearly increases the HRR. For well ventilated solid fuel fires, the HRR increases by approximately 25% relative to a free burn test but the HRR is not sensitive to either tunnel width, tunnel height or ventilation velocity. For solid fuel fires that were not well ventilated, the HRRs could be less than those in free burn laboratory tests. In the case of ventilation controlled fires the HRRs approximately lie at the same level as for cases with natural ventilation.

Tests with liquid and solid fuels in model tunnels (1:20) were performed and analysed in order to study the effect of tunnel cross section (width and height) together with ventilation velocity on ceiling gas temperatures and heat fluxes. The model tunnel was 10 m long with varying width (0.3 m, 0.45 m and 0.6 m) and height (0.25 m and 0.4 m). Test results show that the maximum temperature under the ceiling is a weak function of heat release rate (HRR) and ventilation velocity for cases with HRR more than 100 MW at full scale. It clearly varies with the tunnel height and is a weak function of the tunnel width. With a lower tunnel height, the ceiling is closer to the base of continuous flame zone and the temperatures become higher. Overall, the gas temperature beneath the ceiling decreases with the increasing tunnel dimensions, and increases with the increasing longitudinal ventilation velocity. The HRR is also an important factor that influences the decay rate of excess gas temperature, and a dimensionless HRR integrating HRR and other two key parameters, tunnel cross-sectional area and distance between fuel centre and tunnel ceiling, was introduced to account for the effect. An equation for the decay rate of excess gas temperature, considering both the tunnel dimensions and HRR, was developed. Moreover, a larger tunnel cross-sectional area will lead to a smaller heat flux.

The need for a successful fire and rescue operation in an underground facility, e.g., a tunnel, introduces challenges both in the planning phase and during the incident. This is because these types of facilities can be very complex, and thus, specific tactics are needed compared to the more common incidents, e.g. in residential premises. When planning a fire and rescue operation and developing the tactics many different aspects need to be considered: complexity of the facility, the expected number of people involved in the operation, information available about the incident, the purpose of operation, etc. This paper contains recommendations for firefighting in underground facilities. The recommendations are structured in accordance to the sequential time period during which some specific fire safety design measures are taken. These periods are the design phase, the construction phase and finally when the facility is in operation. The recommendations presented in this paper are based on the results of the Swedish TMU research project (Tactics and methodologies for firefighting in underground facilities), results from other research projects and experience from real fire and rescue operations.

The report contains recommendations for firefighting in underground facilities. This implies results from a research project and the recommendations are based on case studies, interviews, experiments and discussion with different fire departments. The recommendations are structured in accordance to the time period of the actual incident occurrence or the time period during which some specific measures are taken. These periods are project period, construction phase and finally when the facility is in operation. The recommendations are based on the work in the TMU project (Tactics and methodologies for firefighting in underground facilities), results from other research projects and experience from real fire and rescue operations.  

The report compiles the results from the TMU-project. The focus is on fire-fighting performance, capability and organization in underground constructions. The emphasis was on large-scale testing with authentic fire conditions and fire-fighting equipment, development of tools for prediction of hazardous conditions and capabilities of  fire-fighting during different conditions, organizational management and tactics, education and development  of recommendations.  The project was divided into different work packages and these are presented in this final summary report. The test fires performed in the project created severe conditions for fire-fighters who moved in smoke for over 180 m before fighting fully developed fires in a range of 18 to 33 MW. The fires consisted of wood pallets placed in a semi-open steel container, simulating a train wagon fire. The walking speed and connection time for hoses and connections were registered and documented by infra-red cameras. The most important results from these tests is that the time taken to approach the fire depends on parameters as type of equipment, preparation, possibilities for use of infra-red (IR) cameras and the capacity of the extinguishing media. The heat radiation from the fire was found to be important to overcome in order to get close enough to fight the fire. Recommendations and tactics for fighting fires in underground constructions are given. 

A fire development analysis of three series of metro carriage fire tests in different scales was carried out. These metro carriages fire tests included 1:10 model scale tests, 1:3 model scale tests and 1:1 full scale tunnel tests. The heat release rate (HRR) correlations between different scales of carriage fire tests were carefully investigated. The mechanism of fire development is very similar in different scales of tests involving fully developed fires. After the critical fire spread, the fire travels along the carriage at an approximately constant speed. The maximum heat release rate obtained for a fully developed fire is dependent on the ventilation conditions and also the type and configuration of the fuels, and a simple equation has been proposed to estimate the maximum heat release rate. A global correction factor of the maximum heat release rate is presented and examined. 

Within the interdisciplinary research project METRO, two full-scale fire tests were performed with ignition inside commuter train carriages in a tunnel. Both tests developed to fully flashover conditions. The fire development was very different in the two tests. The main reason was the difference in initial combustion behaviour between the case with combustible wall and ceiling lining, and the case with a refurbished carriage using aluminium sheet covering the combustible lining as the exposed interior surface. In the case with combustible lining a ceiling flame was developed, radiating towards the seats and the luggage spreading the fire more quickly than in the case without exposed combustible lining. Also in the gas concentrations, significant differences could be observed between the two tests. During the tests, concentrations of O₂, CO and CO₂ were sampled and analysed at three different heights. The paper focuses on the time resolved results of the gas concentration. The development in gas concentration at different levels is presented and discussed in relation to the fire development in the carriage. Results from calculations of time to incapacitation and fractions of an incapacitating does are also included.

This report summarizes a study on fire safety during industrial handling and storage ofsolid biofuels, biomass and various waste fractions. The intention has been to collectknowledge and experience which could be of important use for the industry but alsoprovide a platform for future recommendations and to define the need for future researchprojects. The study has involved an analysis of fire statistics based on the fire incidentdatabase managed by MSB (Swedish Civil Contingency Agency) for the period 2005-2013. A questionnaire was also distributed to relevant industries to collect information onwhat kind and quantities of materials they handle, how these materials are stored, etc.Some questions also related to their own experience of fire incidents, such as number offires per year, estimated costs, amount of burnt and damaged material. A separatequestionnaire was also distributed to the Swedish provincial offices (länsstyrelser) whoare issuing the permissions for these kind of storage facilities. The questions were hererelated to fire safety requirements that are stipulated in the permission process. Both theindustry and the provincial offices were also asked for their opinion about the need forfuture research. The report also summarizes some related research reports and someexamples and experience from typical fire incidents.The study shows that there are about 200 fires annually in this types of handling andstorage facilities in Sweden and the trend is slightly decreasing. A majority of the firesoccurs in outdoor pile/stack storage. Based on figures from 2011 and 2012, the totalamount of material which is burnt and/or damaged per year is estimated to about 6500-7500 ton/year and the yearly cost to about 150-350 million SEK. However, in case of oneor a couple of large scale fires during a specific year, these figures might increasesignificantly.This study could form the basis for the development of a handbook to be used by theindustry and authorities to improve the fire safety in a cost effective way at the storagesites.

This report summarizes a study on fire safety during industrial handling and storage of solid biofuels, biomass and various waste fractions. The intention has been to collect knowledge and experience which could be of important use for the industry but also provide a platform for future recommendations and to define the need for future research projects. The study has involved an analysis of fire statistics based on the fire incident database managed by MSB (Swedish Civil Contingency Agency) for the period 2005-2013. A questionnaire was also distributed to relevant industries to collect information on what kind and quantities of materials they handle, how these materials are stored, etc. Some questions also related to their own experience of fire incidents, such as number of fires per year, estimated costs, amount of burnt and damaged material. A separate questionnaire was also distributed to the Swedish provincial offices (länsstyrelser) who are issuing the permissions for these kind of storage facilities. The questions were here related to fire safety requirements that are stipulated in the permission process. Both the industry and the provincial offices were also asked for their opinion about the need for future research. The report also summarizes some related research reports and some examples and experience from typical fire incidents.The study shows that there are about 200 fires annually in this types of handling and storage facilities in Sweden and the trend is slightly decreasing. A majority of the fires occurs in outdoor pile/stack storage. Based on figures from 2011 and 2012, the total amount of material which is burnt and/or damaged per year is estimated to about 6500-7500 ton/year and the yearly cost to about 150-350 million SEK. However, in case of one or a couple of large scale fires during a specific year, these figures might increase significantly.This study could form the basis for the development of a handbook to be used by the industry and authorities to improve the fire safety in a cost effective way at the storage sites.This report is a summary of the full project report (SP Report 2014:55) which includes significant more detailed data.