On Christmas Eve 1953, train No. 626 left Wellington at 3.00pm bound for Auckland with four first-class carriages and five-second class carriages, a brake van and a postal van. The train was carrying a total of 285 passengers and crew. The night was clear and the weather was fine. At 10.20pm, the train passed the Tangiwai Flag Station, which was located approximately 1 mile (1.6 kilometres) from the rail bridge over the Whangaehu River. It was reported to be travelling 'slower than usual' at about 40 miles per hour.
Five minutes beforehand, at approximately 10.15pm, the central pillars of that same rail bridge (No. 136) had been swept away by the raging floodwaters of the Whangaehu River after a lahar roared into the river from a crater on nearby Mount Ruapehu. The lahar was caused by the collapse of the walls containing the crater-lake on the mountain, which allowed the lake waters to flow down the mountainside picking up large quantities of volcanic ash and boulders to form a thick slurry of rapidly travelling mud. The slurry reached Tangiwai in the form of a dense wave of water, sand and boulders. Geologist James Healy reported as follows:
Above the railway bridge the flood spread out across the flats, depositing sand and boulders and reached a depth of 20 feet [6.01 metres] at the bridge. It piled up to cross the highway and highway-bridge, depositing sand and flooding across the highway for several hundred yards, and swept on down the river.
The lahar was estimated to have a density of approximately 1.6 pounds per cubic inch, and a speed of approximately 10 miles per hour. This meant that the lahar had transporting abilities many times that of a normal river in flood, and Healy estimated that the fourth pier of the bridge would have been carried away in its entirety almost immediately after first contact by the lahar. Upstream from the bridge, boulders up to 4 feet (1.2 metres) in diameter were found. Forty-five minutes later, the river had subsided markedly, and by daybreak the scene resembled a 'mud estuary at low tide'. The flood rise in the river, which measured between 15 to 17 feet (4.6 to 5.2 metres), also destroyed Strachan's bridge at Karioi, Ngamoki Bridge, and the Whangaehu Valley Road Bridge.
At 10.22pm, shortly after the lahar had reached the bridge, the Wellington to Auckland express train No.626 approached the bridge site. Seconds before Arthur Cyril Ellis, a postal worker from Taihape, had waved a torch in an attempt to stop the train causing the driver, Charles Parker, to make an emergency application of the breaks. He was too late. The locomotive KA949 and the five second-class carriages of No. 626 tumbled into the swollen river. The sixth carriage was left dangling at the end of the rails at about a 45-degree angle. A witness standing on the road on the northern bank of the Whangaehu River observed the locomotive suddenly nose-dive into the river; and noted that 'the rest of the train was left stationary with the lights burning in the carriages'. The noise of the roaring river and boulders was, in his words 'terrific' and he could not hear the train crash as it plunged into the water. Ellis saw the carriages that had fallen 'floating down the river with the lights still on'. Ellis noted that 'after they had travelled about 40 yards they disappeared and I no longer saw the lights'. In an attempt to rescue the passengers in the sixth carriage, Ellis and guard William Inglis boarded the train. Shortly afterwards, the carriage plunged into the river. With the assistance of two passengers, Ellis and Inglis managed to rescue 21 of the passengers trapped on board by lifting them through the broken windows of the carriage.
Within half an hour further help had arrived, and a Disaster Co-ordination Centre was set up at the Ohakune Railway Station. Army personnel from Waiouru and Navy personnel from HMS Irirangi, as well as civilians helped to retrieve the bodies and rescue the survivors, many of whom were 'shocked, filthy, choked with silt and half blind with oil'. Of the 285 persons on the train, 134 were found to be safe. Altogether, the bodies of 131 people, most of whom had either drowned or been asphyxiated by silt, were recovered. A further 20 were never found, bringing the casualty list to a total of 151 persons. Heavy moving equipment arrived from north and south and carriages and debris were removed. In the meantime rail traffic was diverted via New Plymouth and road traffic through the back roads. The Public Works Department and the Railways Department worked night and day and within a week the rail line was re-opened with temporary central pillars for the bridge in place.
The news of the disaster became known to most New Zealanders early in Christmas Day and what was then the world's eighth biggest railway disaster 'shocked celebrations to a standstill'. An information bureau was established at the Railway Social Hall in Wellington and was open 24 hours a day to answer queries about the accident. The bodies of the victims were transferred to Wellington on 28 December and, on 31 December 1953, a ceremony was held to inter the unidentified victims in the Karori Cemetery. Prince Phillip, who had arrived in Auckland with Queen Elizabeth II just 40 hours before the accident, attended the funeral. On the last day of her tour the Queen awarded the George Medal and British Empire Medal to those who had distinguished themselves during the aftermath of the disaster.
On 18 January 1954 the then Prime Minister Sidney George Holland (1893-1961) established a Board of Inquiry to establish the cause of the disaster, determine whether it could have been prevented and to inquire into methods of preventing a similar occurrence. The Board reported its findings on 23 April 1954. It found that the cause of the accident had been the 'sudden release from the Crater Lake on Mount Ruapehu'. The Board emphasised the destructive nature of this release and found that no government personnel were to blame for the collapse of the rail-bridge. However, the Board also noted that it was known that lahars had occurred in the Whangaehu in 1861, 1889, 1895, and 1925, and that severe flooding had resulted on at least four occasions. The recommendations of the Board that measures be undertaken to prevent a similar accident were heeded and resulted, in 1968, in the establishment of an early warning system upstream on the Whangaehu River.
A year after the disaster, the Wellington to Auckland express dropped a wreath into the Whangaehu River from the new railway bridge in memory of those who had died. It was the first act to commemorate the disaster and has since become a tradition. The first official memorial of the disaster was unveiled at the Karori Cemetery in Wellington on 26 March 1957. Designed by government architect Francis Gordon Wilson (1900-1959), the memorial includes a marble stone inscribed with the names of the 151 victims of the disaster and is constructed around the graves of the 16 victims unidentified at the time of the burial. On the tenth anniversary of the disaster, on 24 December 1963, more than 300 people journeyed to Tangiwai, where a small white cross, erected for the occasion, marked the site of the disaster. Family and friends of those who had died had informally observed the anniversary of the accident at the Tangiwai site, and shortly after the anniversary, survivors, descendants and relatives of those who perished, union representatives and corporate sponsors formed the Tangiwai Disaster Memorial Committee. The aim of the committee was to obtain sufficient funds to 'erect a suitable shrine on the site and to provide an engineering scholarship in the field of travel safety'. Their patron, politician Walter Nash (1882-1968) launched their appeal for funds in 1964.
While an informal ceremony continued to be held each year at Tangiwai in memory of the disaster, the permanent marker was not completed until 1989. It was designed by the New Zealand Master Monumental Masons Association Inc and erected by Anderson Memorials, Wanganui. Its primary sponsors, who are acknowledged on the memorial itself, included members of the Lions and Lioness clubs of Ruapehu, Waiouru, Taihape and Hunterville; New Zealand Timberlands Ltd; National Radio; the New Zealand Railways Incorporation; and NZ Master Monumental Masons Association. The memorial, which consisted of a circular platform outlined with river boulders, and an obelisk made from granite, was located where the wrecked carriages of the train had lain. On 14 June 1989 survivors of the disaster and relatives of those who had died joined more than 200 people for the unveiling ceremony. The memorial was dedicated by the Reverend Tom Hawira of Raetihi and a service was conducted by Father Neal Wilson of Waiouru and now serves as a focus for the annual memorial ceremony. In 1994 the site was made an historic reserve.'
Sunday 21 December 2003 was the 50th anniversary of the disaster. A small ceremony attended by approximately 40 people, was held at the Tangiwai National Memorial in Karori Cemetery in Wellington. This ceremony was attended primarily by the families of those buried at the site. Yet the main ceremony was held at the site of the disaster, at Tangiwai, where the obelisk was unveiled for a second time following the addition of two new inscriptions. The ceremony was attended by approximately 1000 people, including the Governor-General, the Prime Minister, Ministers of the Crown, Members of the Opposition, and personnel from the Army, Navy and civilian rescue organisations, as well as the survivors and families of the victims. The Tangiwai site, with its proximity to the actual disaster site, remains the most important focus for New Zealanders of the country's worst railway disaster.
