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Safer underground metro systems possible with results from Swedish METRO project

The Swedish METRO project has shown that fires in trains can be greater than previously estimated, but also that the design of trains and the choice of materials is progressing in the right direction. The outcome of the fire can be very different depending on the choice of materials as well as if the doors of the trains are open or not.

- The project is unique since many organizations, with different skills, work together to make underground metro systems all around the world safer, says Mia Kumm, one of the initiators of the project, at Mälardalen University.

Complex tunnel systems lead to increased risks of serious accidents. Severe fires in metro systems make both evacuation and fire and rescue operations difficult. How quickly the fire develops is a key factor for the available safe time for evacuation. Now the results and the recommendations from the three-year joint safety in infrastructure research project, METRO, have been published.

Some of the most important results from the research project are new new knowledge of how quickly people can be evacuated from trains in tunnels, what difficulties are encountered for people with disabilities in evacuation situations, how trains can be designed to decrease the risks of personal injury in case of explosions and what possibilities and limitations there are for fire and rescue operations.

The METRO project has shown that way-finding is very difficult in smoke-filled tunnels, but the researchers have also identified a number of way-finding systems which efficiently help people to find the right way out.

- One interesting discovery is that even simple sound based systems work better than many of the conventional visual systems used today, says Daniel Nilsson, at the Department of Fire Safety Engineering and Systems Safety at Lund University.

Trains and metro carriages of today fulfill high fire safety standards, but the carried fire load - bags and luggage the passengers bring on board - can be the determinant factor for whether the fire develops into flashover or not.

- It has shown to be of great importance whether the doors of the trains are open or not and what type of interior lining material is used. Platform screen doors can have a big influence on both the fire spread and of the evacuation situation, says Professor Haukur Ingason at the SP Technical Research Institute of Sweden.

In the autumn of 2011, full-scale fire tests were carried out in one of the Swedish Transport Administration's abandoned tunnels outside the city of Arvika. In a global perspective, few full-scale tests have been carried out since they require large financial resources and a comprehensive organization. When constructing new tunnels different computer models are often used to simulate fires and smoke spread. Full-scale tests are of great importance to verify these models and make calculations more accurate.

Conclusions - in short - Fires in trains have been found to be larger than earlier expected. When designing ventilation systems, at stations with an older rolling stock, higher design values than commonly used today needs to be counted for. - The carried fire load can be the factor that makes the fire turn to flashover. - Sound based way-finding systems at emergency exits can be a very effective way to guide people to the exits in smoke filled tunnels. - Platform screen doors should be used in one-exit underground stations as a part of the technical fire safety solutions to prevent smoke spread. - Designers should consider the risk for jammed doors in secondary carriages due to explosion. - New search patterns and interpretation of IR-imaging in tunnels should be developed for the rescue services.

Questions about the project Mia Kumm, Project secretary, Mälardalen University: +46 21-10 70 29, +46 70-330 30 90, e-mail: maria.kumm@mdh.se

Haukur Ingason, Project leader, SP Technical Research Institute of Sweden: +46 10-516 51 97

Daniel Nilsson, Assistant project leader, Lund University: +46 46-222 95 93 About the METRO-project

The METRO project is a large research venture dealing with fire and safety in underground mass transport systems, mainly underground railways. METRO is led from Mälardalen University and comprises over 14 million SEK, with a supplementary project of 4.8 million SEK, led by SP Technical Research Institute of Sweden. In METRO, researchers cooperate interdisciplinary across organizational boundaries. The research findings will improve safety in underground rail systems, but the knowledge will be able to be used in many different kinds of underground installations.

Participating in the project is: Mälardalen University, Lund University, SP Technical Research Institute of Sweden, FOI (the Swedish Defense Research Agency), Gävle University, the Swedish National Defense College, the Swedish Fortifications Agency, The Greater Stockholm Fire Brigade and SL (Stockholm Public Transport).

The project is funded by: SL, The Swedish Research Council Formas, the Swedish Fire Research Board, the Swedish Transport Administration, MSB (the Swedish Civil Contingencies Agency) and the Swedish Fortifications Agency.

Background to fires in tunnels What burns in tunnels is, in most cases, one or more vehicles of some kind. The special thing about tunnels is partly the ceiling, and partly the tunnel itself. The ceiling causes the flames to deflect and the flames, fumes and the ceiling heat radiate towards people and various objects in the tunnel. The hot and poisonous fumes move along the tunnel, thus constituting a great hazard to people who are in the tunnel or at nearby stations under ground level. The fire also spreads more easily to nearby vehicles, thereby increasing in intensity much quicker than out in the open. Source: Anders Lönnermark, SP

idw :: 16.01.2013