FIRE COULD have broken out in the Kaprun mountain railway train before it entered the tunnel, it was claimed this week.
Investigators are not ruling out any possible causes, though molten material has been found on the 601m long viaduct leading to the tunnel. This suggests the train may have been on fire when it went underground.
An eye witness account of a 'number of explosions' from the train on the viaduct is also being investigated.
Teams of criminal, army, medical and technical investigators have been in the tunnel since Sunday, identifying victims and trying to work out the cause.
High winds, water, darkness and falling rocks have all hampered the 'centimetre by centimetre' investigation.
Gerald Valentin, a Saltzburg Government geologist, explained how the very high temperatures - 'over 1,000degreesC' - had damaged the rock and made it liable to fall.
'The chalk mica schist rock had been burnt badly 50mm deep and at faults and joints up to 350mm.'
He has been supervising the army which is making the tunnel safe for investigation by knocking down loose rock. He estimated 3t of the metamorphic rock had been removed from the tunnel roof with hammers and bars.
Chemical, toxicological and biological samples have been taken from the bodies and track.
Three teams of investigators are working in one and a half hour shifts in the difficult physical and psychological circumstances.
Investigators had to enter the tunnel from an escape passage at its mid point as it was unsafe to enter from below until the train was secured. The train has been confiscated by the Ministry of Interior pending the results of investigations into the blaze.
The investigation team is looking at possible defects on the train and track. It is also checking to see if anything fell onto the train.
Representatives from the train manufacturer are trying to discover why the supposedly fire retardant train materials burnt so fiercely.
Government engineer Christian Tisch said lubricants used on the cable and track and mechanical friction were being looked at.
Smoking is not allowed on the train, but a spokesman said: 'There were a lot of teenagers on the train, so who knows.'
Potentially flammable equipment, such as gas canisters and fuel, are only transported at night when there are no passengers on board.