Press Releases（Archive）
FY2012 - FY2003

To clarify the process by which the Toki No. 325 Shinkansen derailed on October 27, 2004, JR East formed a committee, the Joetsu Shinkansen Derailment Investigative Special Committee (Chairman: Executive Director Tanaka). For the past year, the committee has been analyzing the damage done to structures, tracks, rolling stock and other property, as well as structures and debris at the derailment site. It has also conducted boring tests to survey the rail bed in the vicinity of the derailment.
The Air and Rail Accident Investigation Committee of the Ministry of Land, Infrastructure and Transport is continuing to investigate how this derailment happened.
We have received complete cooperation from the Railway Technical Research Institute in surveying, analyzing our data.

(1) Derailment caused by ground movement
Incidents involving structural damage and/or structural collapse were minimal, and we do not believe that they were factors leading to the derailment. We believe that the derailment was due to ground motion caused by the earthquake.

(2) A total of 22 axles derailed due to the earthquake and subsequent damage.
From the traces remaining on the tracks, we determined that the fourth axle of Car. No. 10 (the car closest to Niigata in the direction of travel) derailed first in the vicinity of 206.227 km. Several other derailments followed, with a total of 11 axles derailing.
Furthermore, the tracks were damaged when the wheels derailed, and in some places the distance between the right and left rails broadened, causing subsequent axles to derail. We estimate that in the end, 22 out of 40 axles on a 10-car train derailed.

(3) The train continued to be guided by the rails
We believe that the train maintained its conformation until it stopped because none of the cars in the train separated, and since the rails were pinched between the wheels and parts of the bogie at several places after the fourth axle of Car No. 10, the train was able to continue running along the rails.

(4) Car. No. 1 slid toward the Chuo Return Channel after joints broke
Many derailed wheels broke off at the IJs (Insulated Joints between rails) at 206.696 km, and we believe that since the wheels and other parts hit the rails close to where these joints disconnected, the rails were greatly deformed in the direction of the Tokyo-bound tracks. As a result, Car No. 1, the last car, was forced toward the central return channel, which lies between the Niigata-bound and Tokyo-bound tracks.

Based on the results of our investigations so far, the Air and Rail Accident Investigation Committee's January 2005 progress report, and the Intermediate Summary Report of the Shinkansen Derailment Prevention Consultations (Railway Bureau of the Ministry of Land, Infrastructure and Transport, March 2005), we are developing proposals for measures to prevent derailments. The following three measures are currently in the prototype stage.

• Rolling Stock Guide Mechanisms
  To prevent rolling stock from deviating greatly from the rails after a derailment
• Improvement of Rail Fastening Devices
  To prevent rollovers or major shifts in the rails so that rolling stock can continue to be guided by the rails, even if a car derails and the rail fastener is damaged.
• Improvement in Glued Insulated Joints
  To prevent glued insulated joints from being broken by derailed wheels

	Summary [PDF/195KB]
	Rolling Stock Guide Mechanism [PDF/102KB]
	Improvement of the Fastening Device [PDF/152KB]
	Improvement of the Glued Insulated Joints [PDF/144KB]

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