Experts warned of a flaw in the Shinkansen's quake-detection system. It was exposed Saturday. `It's almost a miracle that no one was injured.' TECHNICAL EXPERT Japan Railways group
Pictures of the derailed Shinkansen flashed around the world as Japanese railway technicians and officials shook their heads in shock.
The belief was shattered: The mighty Shinkansen, the pride of Japanese technology, can derail.
The 10-car Toki No. 325, speeding at 200 kph in the Chuetsu area of Niigata Prefecture on Saturday, became the first bullet train to derail in the Shinkansen's 40-year history.
That was caused by the first big jolt in a series of earthquakes over the weekend that exposed a flaw in an early quake-detection system widely touted by officials of the Japan Railways group companies.
But the record of no deaths in a Shinkansen accident remains intact-thanks to some fortunate circumstances.
``It's almost a miracle that no one was injured,'' said a JR technical expert.
More than 150 passengers were on board the train on the Joetsu Shinkansen Line when eight of its cars went off the tracks.
Experts say Toki No. 325 did not overturn because it was traveling on a straight section and was reducing speed for the next stop, Nagaoka Station.
``Risks of derailment generally increase as the speed increases,'' said Fumio Yamazaki, a professor of earthquake engineering at Chiba University.
A greater speed, curving tracks and another train coming in the opposite direction would have been disastrous.
A three-member team of the transport ministry's railway accident investigation panel started inspections Monday into details of the accident-and into the safety weak spot.
The Shinkansen's main anti-quake measure is called UrEDAS (Urgent Earthquake Detection and Alert System), whose Japanese pronunciation (Yuredasu) means ``to begin shaking.'' East Japan Railway Co. (JR East), which operates the Joetsu Shinkansen, uses a similar system.
With seismometers planted every 20 kilometers along Shinkansen lines, the high-tech devices immediately detect the fast-reaching weaker primary wave (P-wave) of an earthquake and shut off the train's power in less than 3 seconds. The idea is that the Shinkansen will stop or be traveling at a safer, slower speed when the stronger secondary wave (S-wave) arrives and the ground begins to violently shake.
The system is considered effective for large quakes, which usually occur deep underground where tectonic plates meet, providing more time between the P- and S-waves.
But quake experts had warned that the system would be ineffective for temblors occurring close to the Earth's surface. And that is what happened on Saturday.
The Joetsu Shinkansen system detected the P-wave and cut off power. But the S-wave arrived at almost the same time because the focus, or underground center of the quake, was so shallow and the train was near the epicenter.
According to JR East officials, the driver applied an emergency brake the moment he felt the quake's jolts, which nearly shook him off the driver's seat. He was quoted as telling the officials that power went off at the same time.
The Niigata-bound train derailed about 300 meters after passing through a tunnel. The wheels on 22 of its 40 axles went off the rails and screeched along the concrete for more than 1,700 meters. When it finally stopped, the last car was tilting at a 30 degree angle over the Tokyo-bound tracks.
JR companies had stepped up efforts to prevent disasters, including upgrades and wider use of the UrEDAS system. But as the Niigata quake has shown, there is currently no sure-fire way to protect running trains against earthquakes.
Some experts say the UrEDAS will fail in Shizuoka Prefecture if the long-expected Tokai earthquake should hit nearby.
``We can do nothing with the UrEDAS alone for a quake that hits from directly underneath as the time is short between the preliminary jolt and the big one,'' a West Japan Railway Co. (JR West) official said.
Overseas media provided extensive coverage of the Niigata earthquake, with some focusing on the Shinkansen derailment.
In Taiwan, which will open a train system next year using Shinkansen technology, several newspapers printed photos of the derailed train on their front pages.
The bullet-train derailment was also featured in the French media. France's TGV is vying with the Shinkansen for contracts for high-speed trains connecting Beijing and Shanghai.(IHT/Asahi: October 26,2004)