Tangiwai is a locality to the south of Mount Ruapehu (the North Island’s highest mountain). Tangiwai is ten kilometres west of the town of Waiouru, and the site of a rail bridge over the Whangaehu River. It’s a quiet spot just off the highway, the river looking more of a stream as it rambles along its gravelly bed.
The scene was very different sixty-one years ago, on Christmas Eve 1953, when this was the site of New Zealand’s worst-ever rail disaster; at the time it was the word’s eighth-worst.
Mount Ruapehu is an active volcano. It had erupted in 1945, but had appeared quiet since then, and was not being monitored. After the 1945 eruption the mountain’s crater lake had slowly refilled, and by 1953 it was eight metres above its 1945 level.
That large body of water was only held in place by a mass of slushy rubble and ash, and at 8 p.m. on Christmas Eve 1953 the debris at the lake’s outlet collapsed. Approximately 340,000 cubic metres of water poured down the mountain and into the Whangaehu River, picking up sand and boulders as it went, forming a volcanic mud flow known as a lahar. Around 10 p.m. the lahar struck the railway bridge at Tangiwai, partially collapsing it just as the Wellington to Auckland express train drawn by Ka949 was approaching.
285 passengers and crew were aboard the train, most travelling home for Christmas. The driver applied the brakes when he saw a local man running towards them waving a torch, but it was too late.
The train leapt out over the bridge. The engine and first carriage landed against the opposite bank; the next four carriages plunged into the torrent; a further carriage dangled over the river until its coupling collapsed and it tumbled in.
One carriage was swept more than two kilometres downstream. Others were jammed against the riverbanks or dragged across the flooded highway.
It took days to recover the dead and injured; twenty bodies were never found, probably washed out to sea 120 kilometres away. Searchers out looking for victims found battered toys and gifts, many of which must have been intended for the loved ones waiting to meet the train at stations along the line.
151 people died in this disaster, and Tangiwai’s name, which means “weeping waters”, was all too appropriate.
Today the crater lake is carefully monitored, and a lahar alarm is in place. There was little to recall this place’s tragic past when I visited Tangiwai at Christmas 2014, just after the 61st anniversary of the disaster.
Although the Tangiwai disaster happened before I was born, it’s always loomed large in my awareness. My parents were booked to travel on this very journey, but for some reason they changed their minds and took an earlier trip. As I stood looking out at the quiet stream and the rebuilt bridge, I was very aware that but for that change of mind I might never have been born at all.
More on the Tangiwai disaster at NZHistory.net