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2016年4月22日 (金)

新幹線脱線 地震対策の総点検を

--The Asahi Shimbun, April 21
EDITORIAL: Kyushu quake exposes potential safety problem for Shinkansen
(社説)新幹線脱線 地震対策の総点検を

The powerful earthquake in Kyushu has exposed a potential weakness of Japan’s reputed Shinkansen technology by disrupting operations of the Kyushu Shinkansen Line.

An out-of-service bullet train carrying no passengers derailed about 1.3 kilometers south of JR Kumamoto Station following the earthquake that rocked southern Japan on April 14.
Kyushu Railway Co. (JR Kyushu) has also found damaged Shinkansen facilities at about 150 locations, including cracks in elevated bridges and fallen parts of noise-blocking walls.

JR Kyushu on April 20 resumed operations on a section of the Shinkansen line between Shin-Minamata Station in Kumamoto Prefecture and Kagoshima-Chuo Station in Kagoshima Prefecture. But there is no telling when the company can restart operations on the remaining northern portion from Shin-Minamata Station to Hakata Station in Fukuoka.

This is the third derailment caused by an earthquake in the Shinkansen’s history of over half a century, following one in 2004 caused by the Niigata Chuetsu Earthquake and one in 2011 triggered by the Great East Japan Earthquake.

The Kyushu Shinkansen train ran off the rails after the nighttime April 14 quake, which measured a maximum 7 on the Japanese intensity scale in Mashiki.

The violent shaking derailed all six cars of the train, which was running at a speed of around 80 kph. Fortunately, no passengers were on the train, and the driver was not injured.

If the train were carrying passengers at a higher speed, however, it could have been a major disaster.

Safety should be the absolute top priority for Shinkansen operations, which carry large number of passengers at very high speeds.

The derailment should prompt all JR companies offering Shinkansen services to make sweeping reviews of their bullet train systems and operations to secure greater safety.

Shinkansen lines are equipped with a system to detect preliminary tremors and stop the trains. However, as the Kumamoto accident shows, this system doesn’t work when earthquakes occur close to the lines.

Since this problem was exposed by the Niigata Chuetsu Earthquake, JR companies have been taking steps to prevent quakes from causing derailments.

JR Kyushu has been working to install “derailment prevention guards” for 55 km of the Kyushu Shinkansen Line, or slightly over 10 percent of both the inbound and outbound bullet train lines.

The guard is designed to prevent the wheels from veering off the track by sandwiching them with the rail. The company has already installed the guards on 48 km of the planned sections.

The project covers sections in areas over active faults. But the accident site was not covered.

JR companies have made their own decisions on which sections of their Shinkansen lines should be protected by anti-derailment guards. Their decisions are based on estimates of the risks of severe quakes.

Central Japan Railway (JR Tokai) decided to install the guards for 596 km, or 60 percent, of the Tokaido Shinkansen Line. The company has already finished work for 360 km under the project.

On the Sanyo Shinkansen Line, operated by West Japan Railway Co. (JR West), the protection guards had been installed on 110 km as of the end of last year. JR West plans to extend the protected sections by another 110 km.

East Japan Railway Co. and Hokkaido Railway Co. are installing different types of anti-derailment systems on their Shinkansen lines.

The Kumamoto earthquake underscores the risk of a huge destructive force occurring at unexpected locations directly below urban areas.

The JR companies should seek opinions of experts to reassess the effectiveness of their current plans to protect their Shinkansen lines from such quakes.

Derailment prevention systems are costly, requiring hundreds of millions of yen per kilometer. In addition, work to install such systems can only be done around midnight when the service is off.
But the JR companies should try to figure out ways to implement their plans ahead of schedule.

The 2011 earthquake damaged poles supporting overhead electric lines beside the tracks.

This time, a chimney of a plant located along the Shinkansen line fell and blocked the rails.

Giant quakes always create unexpected problems. All we can do is glean all possible lessons from each big quake and make steady efforts to enhance safety.


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