Large Scale Fire Tests in the Runehamar tunnel completed

In the frame of Swedish national and European research programs on tunnel safety, comprehensive large scale fire tests have been conducted in September 2003 in the abandoned Runehamar road tunnel in the South-West of Norway.

Especially semi-trailer fires similar to the size of the recent fires in Mont Blanc Tunnel (France/Italy) and St Gotthard Tunnel (Switzerland) were used. The Swedish National Testing and Research Institute (SP) have carried out the tests in collaboration with our  UPTUN* partners from TNO Building and Construction Research in the Netherlands and the Norwegian Fire Research Laboratory (SINTEF/NBL). 

Total four large scale tests with different semi-trailer fire loads were carried out. The worlds highest peak heat release rate ever measured in a tunnel fire test was registered. It was higher than 200 MW and the gas temperatures in the vicinity of the fire were registered above 1350 ºC. The test results from these four tests with semi-trailer cargos have been presented at a symposium in Borås the 20 - 21st of November 2003.

The fire tests were carried out in an abandoned road tunnel owned by the Norweginan Road Administration. The tunnel is a part of a road system that was partly (100 m) destroyed in a landslide.

Why testing?

Fires in European tunnels in recent years have clearly shown the risks and consequences of fires in large vehicles. Over 20 semi-trailers, for example, were destroyed in a single fire in the Mont Blanc tunnel in 1999. Over 50 people have died in these recent fires in road tunnels. Nevertheless, knowledge of the growth and spread of fires in semi-trailers is very limited. The most recent fires in the Eurotunnel (1995), the Mont Blanc tunnel (1999), the Tauern tunnel (1999) and the St. Gotthard tunnel (2001) showed that such fires can develop very high energy release (150-600 MW), involving a dozen or so vehicles.

Test programme

Test nr Test date Test Commodity Estimated heat content
(GJ)
Longitudinal ventilation
(m/s)
Mass ratio cellulosic
/plastic
1 18th of September Wood pallets and polyethylene pallets 247 3 82/18
2 23rd of September Wood pallets and polystyrene madrasses 135 3 82/18
3 30th of September Furnitures, fixtures and rubber tires 179 3 82/18
4 2nd of October Cartons and polystyrene 62 3 81/19

The purpose of the tests

The purpose of the fire tests is to measure the rate of growth of various types of semi-trailer cargoes and to investigate the heat exposure to the tunnel linings. The purpose is also to obtain information to assist a new approach to fighting fires in tunnels. The information will be used to develop design scenarios for road tunnels and guidelines for protection of such tunnels. Variation of loads is infinite, but we shall attempt to restrict the number to those most commonly encountered.

The thermal fire power will be measured with aid of a mobile fan of type MVU 125/140 from B I G Brandschutz Innovationen positioned at one of the tunnel openings. This will provide a means of driving the fire gases in one direction and so enabling the thermal power to be measured at the other end of the tunnel with oxygen consumption calorimetry.

A mobile fan unit will be placed outside the tunnel in order to create
ongitudinal flow.

Results

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. In the test T1 with wooden pallets an d plastic pallets the heat release rate was above 200 MW and the gas temperature near the ceiling over 1350 ºC. The heat release rate calculation, gas temperature measurements, and the analyses of the gas composition all showed that after an initial delay (a few minutes of slow flame spread) the danger increased very rapidly. Other parameters studied were the temperature distribution in the tunnel, radiation near the fire, flame length and fire spread. In two of the tests, when the heat release rate was above a certain limit, oscillation inside the tunnel occurred. 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.

European collaboration

These recent tunnel fires have prompted the European Union (EU) to fund both a tunnel network (FIT-Fires in Tunnels) and a large research projects dealing with the question of methods to upgrade the fire safety in tunnels (UPTUN-Cost-effective, sustainable and innovative Upgrading Methods for fire Safety in existing Tunnels and DART-Durable and Reliable Tunnel Structures. In response to this a series of tunnels fire tests are planned under the leadership of SP Fire Technology in collaboration with our UPTUN partners from TNO in the Netherlands and SINTEF/NBL in Norway. The major financial support comes from the Swedish Rescue Service Agency, the Swedish Road Administration, the Swedish Rail Administration, the Swedish Fire Research Board (and from the European Commission through the UPTUN project (SP, TNO and SINTEF/NBL). Promat International in Belgium - and Gerco Beveiligingen B.V. in the Netherlands, sponsor the passive fire protection of the tunnel. The mobile ventilation fan system is sponsored by B I G Brandschutz Innovationen in Germany.

 

 

Inside the Runehamar tunnel. The 1.65 km long tunnel is 9 m wide and
6 m high.
 

 

Industrial sponsors of the Runehamar tests

 

   

 

 

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