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This report is part of the research project “Fire spread and heat release rate of underground mining and tunnelling vehicles – BARBARA”, conducted by a research group at MälardalenUniversity.

The project’s aim is to improve fire safety in mines and tunnels during construction in order to obtain a safer working environment for the people working for the mining companies as well as the tunnelling companies in Sweden or for visitors in mines open to the public.

This report deals with the second step in the project: the investigation regarding fire causes and fire behaviour of vehicle fires in underground mines based upon material from GRAMKO (the work environment committee of the mine and mineral industry in Sweden).

The main purposes of the investigation are:

• To investigate and present fire causes, types of vehicles involved in fires, fire spread and fire behaviour of vehicle fires in underground mines.
• To give recommendations on the continued work with the full-scale fire tests regarding the initial fire and its position.

The conclusions were that:

• With respect to vehicle fires involving only the start object, a typical fire occurs in a loader or a drilling rig and is due to electrical fault – for example short-circuit of cables – in the engine compartment, resulting in a slow and limited fire spread.
• Regarding vehicle fires limited to the start object and an adjacent object is that it usually occurs in a loader and is due to electrical causes, resulting in a slow and limited fire spread. Typically, electrical cables would play an important role when it comes to the fire spread to adjacent objects.
• Vehicle fires involving the entire vehicle usually occur in a service vehicle or a loader and are typically caused by diesel being sprayed – for example due to a pipe/hose coming loose – on the engine, resulting in a rapid fire spread.
• In future full-scale fire experiments involving a diesel loader and a drilling rig, the vehicles will have to be ignited using a diesel fire – for example a pool fire under­neath or inside the engine compartment – that is shielded and positioned close to larger amounts of combustibles – such as tires or hydraulic hoses – and continuously distributed fuels – such as electrical cables – in order to achieve a rapid fire growth and fire spread that eventually engulf the entire vehicle.