How did a train that they called 'fire-proof' become an inferno?

The driver screamed into his radio: "Help us, we are burning."

The driver screamed into his radio: "Help us, we are burning."

The order back from the station: "Stop the train and open the doors."

Last night, as investigators were stumbling through the mangled carriages, there was still doubt over whether the driver of Kaprun's funicular train had time to open the doors. No more was heard of him, and at about the same moment, the power failed along the entire track. If he did open the doors, he almost certainly contributed to the disaster, and stopping in the middle of the tunnel is possibly the worst thing he could have done.

The preliminary investigation into Austria's worst accident since 1945 has already revealed the fire broke out in the back of the space-age train that propelled passengers up towards the Kitzsteinhorn at 36 kilometres an hour. Many passengers crammed into the carriages were able to get out, only to be choked to death and consumed by flames as they tried to escape.

While the original cause of the accident is still unknown, there is no mystery about the manner of their deaths. Experts say the skiers fell victim to the "chimney effect" - a whirlwind of fire and smoke rising rapidly from below.

Franz Schausberger, the Governor of Salzburg province, said: "The blaze spread at a raging speed, like in a chimney." Opening the doors in such an emergency would have been suicidal. It would have created a draught, fanning the flames and enveloping the top section of the tunnel in dense smoke. Rescuers say the only possible escape route turned into a stairway to Hell.

A great many of the bodies were found not inside the train, but on the stairs above the carriages. The passengers tried to run, but were overtaken by smoke.

When the train halted, it was minutes away from the station at the summit. Had it continued its journey, perhaps some of the passengers might still be alive today.

But the procedure for mishaps was that the engines pulling the cable should halt and the driver, who does little more than open and close doors, should let everyone off. There are then just over 10,000 steps to climb to safety.

Fires were not supposed to break out on this marvel of high technology, inaugurated in 1974 and revamped again six years ago. There were no sprinklers, no escape tunnels, no cameras and no plans for a hasty evacuation.

Worse, the investigators were pondering the shocking possibility that the fire had broken out before the train entered the tunnel and travelled 600 metres to its doom, without the driver being aware. Erik Buxbaum, the head of Austrian security, said yesterday: "We have received information that the fire was visible to witnesses outside as the train was entering the tunnel."

The train, as the operating company's technical experts keep pointing out, was "fire-proof". Made of tough aluminium, it was able to transport 180 people up in one go, while the downward carriages would be carrying up to 180 people simultaneously.

The two trains were connected with a steel cable two inches thick. Steel does not burn, but, as it has now been discovered, it does melt. In the intense heat of Saturday morning's fire, believed to be as hot as 1,000 degrees Celsius, the cable fastened at the lower end of the train simply snapped off.

Investigators were still puzzled how such a blaze could develop from perhaps nothing more than an electric spark in the onboard batteries or a lit cigarette. There are no electric motors on board.

The initial suspicions have all been laid to rest. The operating company categorically denies that liquid fuel or gas canisters were aboard. They suspect that some of the passengers might have been carrying fireworks to the ski festival. Another theory is that the safety experts had forgotten to reckon with one thing in their shining "fire-proof" vehicle: passengers' clothing. Skiers, as is commonly known to everyone but apparently train designers, are covered from head to toe in synthetic fabrics. Clothes worn that day by the 180 people on board would easily produce the heat and acrid smoke still oozing out of the tunnel yesterday.

Twelve people, who were at the lower end of the train, made their way out to safety, against all the odds. When the fire began, one passenger broke the window, jumped out, and in total darkness began running back down the tunnel.

One of the 12 survivors recalled: "My only thought was to get out, and I could save myself in the last second because a window was kicked in and I could fight my way outside." This group was lucky. The people who ran up towards the higher ski station all perished.

Since the train was designed as fireproof, it goes without saying that the fire gate fitted at both ends of the tunnel did not have to close automatically. Such a system, triggered by smoke detectors, would have prevented the "chimney effect" and choked off the flames' oxygen supply.

Fire doors are used in many other tunnels, and also on funicular railway tracks similar to Kaprun's. But this "Alpine metro" had had no serious mishaps since 1974. On Saturday morning, they stayed open.

Like the Titanic, the "Alpine metro" was deemed perfect, a feat of engineering. Nothing could possibly go wrong.