Tangiwai railway DISASTER

The Tangiwai railway tragedy, which occurred on Christmas Eve 1953, when a passenger express train travelling from Wellington to Auckland derailed off the Tangiwai Bridge into the flooded Whangaehu River, 10 kilometres west of Waiuru in the central North Island, was was a painful event. Only 134 of the 285 passengers and staff members on board survived, while 151 died, with the majority drowning in the floodwaters.

The rail disaster wrapped our country in grief and made international headlines. The disaster occurred at a particularly tragic time, with many on board carrying Christmas gifts and those waiting to receive them at stations and at home unaware of what had happened. It had a variety of effects on people; many knew of someone who had been involved in the disaster or knew of someone who had changed their plans to go that evening on the train. Tributes came in from around the world, and a memorial service for New Zealanders, families, and friends was conducted in London's Westminster Abbey. The Tangiwai National Memorial site is located just off the main route between Ohakune and Waiuru.

What caused the avalanche of the water from the lake?

The Crater Lake would release water through a small cave, which drifted down through the rivers to the Whangaehu River, according to the Board of Inquiry. Water must have poured through the volcanic ash and volcanic rock alongside the little tunnel, forming another channel beneath the ice at a lower level, according to further examinations. To the right of the little cave, volcanic rock formations had collapsed, forming a massive cave roughly 45.72 meters wide and 30.48 meters high at the entrance. A stream began to pour into the new cave from Crater Lake beneath a mass of fallen ice.

LAHAR OF WATER, SAND & BOULDERS HITS TANGIWAI RAIL BRIDGE'S PYLONS, CARRYING AWAY PIER 4

The lahar, in the shape of a thick wave of water, sand, and rocks, reached Tangiwai at 10.10-10.15 p.m. There appears to have been little or no erosion as the lahar passed, and the gravel flat where the river flows was smothered by a rapidly flowing mass of silt. The water extended across the flats above the railway bridge, depositing sand and rocks, and reached a depth of six meters at the bridge. It piled up to cross the roadway and bridge, spreading sand and floods for many hundred yards before continuing down the river. The vegetation along the banks was swiftly buried by sand, but the vegetation on the river channel was crushed and sanded smooth.

THE TRAIN REACHES THE TANGIWAI BRIDGE

The fourth pier had been removed by the lahar from Mount Ruapehu a few minutes before the train began to cross the bridge. To 10.21 p.m., the train arrived at the unstable bridge, which collapsed under its weight. However earlier, about 7 p.m. slightly over three hours before the express train, a mixed goods train crossed the bridge, and the river looked normal.