Site of Tangiwai Rail Disaster

The Ruapehu eruptions of 1945 emptied the crater lake of water, and filled the crater with lava.This was then blasted away a few months later by renewed eruptions, leaving a wall of tephra, ash and lava around the crater rim. Over the following years, rainwater and snow melt refilled the lake. Then on 24th December 1953 part of the wall gave way, releasing a deluge of water that poured down the Whangaehu Valley, picking up mud and boulders in its path. This lahar reached the railway bridge at Tangiwai, destroying two of the supporting piles, just before the train from Wellington arrived. WIth the driver unable to stop in time, the engine and five carriages hurtled onto the weakened bridge and into the river, whilst the sixth carriage teetered on the edge, before also falling in. In total 151 people died in what is New Zealand's worst ever railway disaster.

Nowadays there is a lahar warning system upstream to monitor sudden changes in the river levels and send an alarm to a control centre if necessary. The signals at either side of the Tangiwai bridge then indicate the danger and trains are warned to slow down and take extreme care when passing over the bridge. The rail and road bridges have also been strengthened and raised to protect against lahar damage.This is in addition to The Eastern Ruapehu Lahar Alarm and Warning System (or ERLAWS), which is a lahar warning system with monitoring equipment at several points on the mountain, including Crater Lake.

A lahar of similar magnitude to the 1953 one occurred on 18 March 2007, also caused by the crater lake wall being breached. The systems all worked well, with trains and motorists being stopped at Tangiwai before the lahar hit. The newly built bridges survived the lahar impact undamaged.

Near to the prominent monument there is a display with lots of information and images about the eruptions of Ruapehu that led to the devastating 1953 lahar, the resulting accident and its aftermath. Find out about the people who risked everything to help, and saved many lives. The memorial also includes parts of the train, and there is a short (10 minutes return) easy walk to a viewpoint beside the railway bridge.
You can also walk down to the river bed, and observe the river sediment that is full of lava boulders and ash that have washed down from the slopes of Ruapehu. Have a look at the rebuilt road bridge to see what engineers have done to make the bridge more resilient to the powerful force of future lahars.