SP Fire Technology is one of the leading institute on fire safety and research on tunnel fires. SP has performed tests and done research in the area of tunnel safety since 1992. Many papers and reports have been published on the subject. List of publications.
In 1994 SP held a conference in Borås entitled : International Conference on Fires in Tunnels, which was a great success with many participants from all over the world. From then until today the work has continued. In 2003 SP again hosted an international tunnel conference: The International Symposium on Catastrophic Tunnel Fires (20-21 November 2003). The proceedings from this conference can be ordered.
In 1991-92 SP was involved in a European project named EUREKA. As a part of the project fire tests in a tunnel in Norway with a large truck loaded with furniture were performed. The EUREKA project was completed during 1995 and the results were compiled. Each one of the participating countries had separate tasks in the project. SP’s part was to measure and calculate the heat release rate (HRR). The results from the EUREKA project can be used for guidance when designing tunnel safety measures.
Here are some of the results from the EUREKA project:
- cold tunnel walls pull down the smoke from the ceiling and the evacuation of people becomes more difficult
- smoke from the fire is drawn back into the fire zone and the tunnel segment can become smoke filled very rapidly
- vehicles can reach flashover in minutes
- the construction of the vehicles has a large impact on the fire growth, steel structures are better than aluminium and plastic
For more details on the results see some of the references in the List of publications.
During the years several different series of fire experiments have been performed, both in real tunnels and in model tunnels. The results from some of these test series are described in the references in the List of publications. Some are still to be reported. The main conclusions from these test series are:
- The smoke spread and smoke concentration, both along the tunnel and over the cross section, is highly dependent on the type of exhaust ventilation and the longitudinal velocity.
- The thermal exhaust ventilation does not prevent smoke spread downstream the exhaust opening in any case whereas the mechanical ventilation does. The efficiency of the thermal shaft is highly dependent on the height of the shaft and the temperature inside the shaft.
- The critical flow rate of the mechanical ventilation, which prevents any smoke spread downstream the exhaust opening, is highly dependent on the longitudinal velocity.
- Fire spread is governed by the longitudinal ventilation, ceiling height and the heat release rate generated
- The fire spreads between vehicles due to heat fluxes from flames crawling along the ceiling
- The influence of the ventilation on the heat release rate is not as pronounce as have been indicated in earlier studies.
- Suppression system prevent fire to spread between vehicles
Fire test in a model scale tunnel simulating a fire in two HGVs.
In 2003 SP was responsible for large-scale fire tests performed in the Runehamar tunnel in Norway. These tests were the largest ever performed in a tunnel where the heat release rate was measured. The aim of the tests was to study the fire development, maximum heat release rate, temperature distribution, flame lengths and fire spread, radiation, and gas concentration in connection with fires in heavy goods vehicles (HGVs) trailer with ordinary cargos (‘non-hazardous’). The fuel loads consisted of mixtures of cellulose and plastics. The main results were that the gas temperatures and maximum heat release rates from this kind of fires with ordinary goods are much higher than suggested by existing guidelines and can be comparable to what is expected to be related to fires in hazardous goods. Details on the results are given in several of the references in the List of publications and the results are discussed and compared to results from other research project in a recently published doctoral thesis. Background and some details on the performance of the tests can be found here.