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Yokohama train crash proves need to check safety of driverless systems

The Yomiuri ShimbunA driverless train operating on an automated system, which was thought to be safe, crashed after traveling in the wrong direction. Such an accident must not be allowed to happen. There should not be overconfidence in these systems, which need to be checked again.

The accident occurred at the starting station of the Seaside Line, which runs through the southern part of Yokohama. The train was supposed to reverse direction to leave the station but instead traveled about 25 meters in the wrong direction and hit a buffer stop at a speed of more than 20 kph. The crash injured 14 passengers, some seriously.

According to an investigation by the line’s operating company and other sources, a wire in the electrical system inside one of the train’s cars had broken. Due to this breakage, it appears a signal from the automatic train operation system indicating that the direction of travel should change was not relayed to the car’s motor.

Although the train was equipped with a device that automatically stops the train when it travels in the wrong direction, this device also reportedly did not work because of the broken wire.

It can be said that the train lacked backup functions to ensure safety in the event that a broken wire or other glitch occurred.

Indeed, many other automated transit systems that operate without drivers have a function that prevents the cars from moving when signal transmissions are cut due to a broken wire. However, trains on the Seaside Line are not equipped with such a function.

The line’s operator cannot escape criticism that it was overly optimistic in its assumptions about safety.

Not the 1st accident

The wire that broke was one of a bundle of about 100. Such wires can snap due to reasons such as being worn down while the train is running. Given that such parts cannot be completely checked during visual inspections, the system needs to be quickly improved.

Three days after the accident, the Seaside Line resumed services with drivers manually operating the trains. Even now, many passengers feel very worried about using the trains. The focus must be on ensuring safety is the top priority when operating trains on the line.

Seven other train lines around the nation use automated, unmanned train services similar to the Seaside Line. These trains run on dedicated tracks, such as elevated tracks, and safety barrier doors have been installed on platforms at their stations. It was assumed such structures made accidents less likely to occur, compared with regular train lines.

Despite this, a New Tram train in Osaka went out of control and crashed in 1993, and in 2006 a wheel came off a train on the Yurikamome line in Tokyo.

Operators of all these lines should learn lessons from the Seaside Line accident and carefully check whether their own systems have any shortcomings.

As they prepare for a shortage of drivers in the future, railway operators are increasingly considering the use of automated trains. East Japan Railway Co. has started test runs involving automatic train operation system on the Yamanote Line in Tokyo.

In response to the Seaside Line accident, the Land, Infrastructure, Transport and Tourism Ministry will launch an investigative panel comprising industry operators and experts. The panel should discuss steps to boost the safety of driverless transit systems from a wide range of perspectives.

(From The Yomiuri Shimbun, June 14, 2019)Speech



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