Japan govt. report analyzes how quake caused bullet train derailment in 2022

A government report on the derailment of a bullet train in northeastern Japan two years ago says the rocking motions of a major earthquake are believed to have made most of its wheels come off the tracks.

The Japan Transport Safety Board released its report on the March 2022 incident on Thursday. A magnitude 7.4 earthquake off northeastern Japan caused the Tohoku Shinkansen bullet train to derail in Miyagi Prefecture, injuring six passengers. Services on the line were disrupted for about two months.

The board's report says the bullet train stopped after a foreshock activated an emergency brake. It says the main shock caused 60 of the 68 sets of wheels to come off the tracks.

The report says experiments and simulations were conducted by a research institute at the request of the board and the train operator, East Japan Railway Company.

The report also says the air spring systems to absorb shaking motions were significantly deformed by the tremor. It says the deformation caused air to be released and this contributed to the derailment.

The train also had metal guides attached to the wheel hubs to prevent them from moving too far from the tracks. But the report says the guides on 12 of these hubs failed to work, causing a deviation of up to 1 meter.

The report points to the need for more sophisticated measures to prevent derailments to ensure the safety of Shinkansen bullet trains.