Death train's heroes and villains

Nearly 50 years on from New Zealand's greatest rail disaster, caused by the cyclic stirrings of a fearsome volcano, have there been any lessons learned from the tragedy?

How did the accident, which cost 151 lives, happen? Was it purely an act of God or did human neglect and stupidity play a part in the train's plummet into the Whangaehu river?

And did the official inquiry into the disaster, which found no one could be held to blame, ignore evidence that the accident was predictable and preventable, thus saving the Government of the day the enormous cost of compensation?

Tonight's Documentary New Zealand re-examines the tragedy which came so swiftly on the packed express train on Christmas Eve, 1953, as it crossed the central North Island's volcanic plateau, en route from Wellington to Auckland.

It also looks at the role of Cyril Ellis, the lone figure who supposedly tried to flag down the train, then certainly saved many trapped passengers, and who became the legendary hero of that black night.

The documentary opens with scene-setting and, using a vintage steam train, reconstructs the doomed journey.

Unfortunately, the makers have not been able to resist an over-the-top "Oh, night of fate" tone to its dramatisation.

But there's plenty of interest in the interviews with survivors - including one who psychically knew not to board the train - and eyewitnesses to the scene of the disaster, including former New Zealand Herald photographer Graham Stewart.

The reconstructions and a re-examination of evidence show that an unsung hero of the night was the train driver, Charles Parker, whose swift efforts to stop the train saved the lives of many of his passengers.

Of most interest, however, is the computer-graphics reconstruction of the bursting of the lahar from Mt Ruapehu's crater lake, and the flow of mud down the lake-fed Whangaehu river bed and its effect on the already weakened Tangiwai rail bridge.

The documentary also looks at the potential danger in the bridge's design and siting at that particular bend in the river.

In 1925 a similar flood had roared down the river and substantially weakened one of the piers of the bridge.

It was this pier, loose in the river bed, which collapsed under the train. Why had it not been repaired?

The board of inquiry ignored engineers' evidence that the pier was a disaster waiting to happen.

It also overlooked evidence that geological warnings had been made about the imminent danger of the rising waters of Mt Ruapehu's crater lake.

The programme interviews two men, Lewis Vause and Jim Mason, who were concerned at the time with the rising lake and tried to make their voices heard about the potential danger to the plateau below.

The Tangiwai disaster, one of the worst train crashes in the world, was a freak accident and one of awfully bad timing.

Had the lahar occurred slightly earlier the damage to the bridge would probably have been apparent and trains alerted.

But, the programme also asks, could it happen again?

The question is timely with the crater lake again rising - eventually to levels which will trigger lahars.

* Documentary NZ: The truth about Tangiwai, TV One, 8.35pm