Safe, reliable 'shinkansen' sparking interest overseas
TAKAYUKI KIKUCHI, Nikkei staff writer
TOKYO -- Shinkansen bullet trains are vital transport links in Japan. Some 900,000 people ride shinkansen trains every day. The high-speed railways, which allow passengers to travel comfortably, safely and on time at up to 300kph are the pride of Japan.
The shinkansen is attracting the world's attention, especially their reputation for safety and comfort and their quick braking and low vibration even at high speeds. The high-speed railways are one of the primary infrastructure exports the government is promoting around the world.
Nozomi trains traveling from Tokyo to Osaka on the Tokaido Shinkansen line, operated by Central Japan Railway (JR Tokai), reach their maximum speed between Shin-Yokohama and Odawara stations. The speed was raised from 270kph to 285kph in a timetable revision on March 14, reducing the time it takes the trains to run between Tokyo and Shin-Osaka stations by about 3 minutes to about 2 hours and 22 minutes.
The time reduction was realized thanks to new air springs that use the elastic force of air to move the train up and down. When a train takes a curve at high speed, it and its passengers are subjected to centrifugal force toward the outside of the curve. Since centrifugal force makes passengers feel uncomfortable, the speed is adjusted at each curve to reduce the force to a preset level. At a curve, the air springs tilt the train, lifting its external side so that the force resulting from the combination of gravity and centrifugal force acts vertically to the floor of the tilted cars.
The latest model on the Tokaido Shinkansen line, the N700A, has larger-capacity tanks to supply air to the air springs so that it can maintain higher speeds over longer distances. To raise the speed by 15kph, JR Tokai conducted running tests totaling 43,000km from February 2012 to October 2014. The N700A also uses a constant-speed running system, a new device to make the train follow speed instructions by automatic train control, enabling it to run stably at higher speeds.
Providing both high speed and a comfortable ride is a challenge for other shinkansen models as well. On the Hokuriku Shinkansen line, which was extended to Kanazawa on March 14, passengers feel little vibration in the Gran Class luxury car. Along with extra-comfortable shock-absorbing seats, the car actually moves in a way that cancels vibrations.
This is due to a system called active suspension. When a sensor detects tilting, the system uses compressed air to move the car in the opposite direction of the tilt, automatically counteracting the swing. The system was developed by Nippon Steel & Sumitomo Metal. The company also provides the same system for limited express trains of Odakyu Electric Railway, Keisei Electric Railway and Kyushu Railway (JR Kyushu).
Safety, which is the most important, is also supported by high technology. On the Tohoku Shinkansen line operated by East Japan Railway (JR East), all the Series E5 trains, which run at a maximum speed of 320kph, were able to stop safely when the massive earthquake and tsunami struck in March 2011. The trains quickly detected the quake and actuated sudden braking. It is no easy matter to suddenly stop a train running at such high speeds, but the improved structure of the brakes made it possible. Shinkansen trains use disc brakes, which stop the train by pressing brake pads against metal discs that rotate with the wheels.
If a train running at over 300kph is suddenly stopped, the temperature of the discs pressed by the brake pads rises above 800 C, which deforms the discs. This reduces the area in contact with the brake pads, rendering them unable to produce sufficient braking force. To solve this problem, Akebono Brake Industry put a spring under the friction material that comes into contact with the disc so that the pad can move along the deformed shape, according to a company official. This keeps the area of the disc in contact with the brake pad from decreasing even if the disc is deformed by heat. The number of trains that use brakes incorporating the spring structure has increased in Japan. Akebono Brake is trying to sell the technology to European rolling stock manufacturers as well as domestic makers, emphasizing their performance on the shinkansen trains.
There are moves to sell shinkansen systems overseas. In various parts of the world, there are plans to construct high-speed railways totaling over 18,000km in length, according to the International Union of Railways (UIC). JR companies, rolling stock makers including Hitachi and Kawasaki Heavy Industries, and trading companies including Mitsubishi Corp. jointly established the International High-Speed Rail Association in 2014 to promote shinkansen technology overseas.
The association is playing up the shinkansen's safety and reliability for scheduled services in India, Australia and other countries. Although competition with European and Chinese companies is growing intense, "shinkansen is increasing its appeal in India and Southeast Asian countries," said Masafumi Shukuri, chairman of the association.
On a high-speed railway, trains travel at 250kph or faster. Their operation requires not only sophisticated technologies for hardware, including rolling stock, rails and signals, but also advanced know-how for smooth operation and financing the development of infrastructure. Apart from Japan and Europe, high-speed railways have been introduced in only a few countries, including China and South Korea.
Air springs' elasticity is due to air inside a rubber membrane. When a load is applied or air is introduced, the spring increases its elasticity by increasing air pressure. Since they also absorb minute vibrations more easily than metal springs, it is used in the lower parts of buses and trucks as well as rail cars.
Disc brakes operate by squeezing brake pads made of a friction material, against a disc rotating on either side of a wheel to slow and stop its rotation. The brakes convert the kinetic energy of the wheel into thermal energy through friction and discharges the heat from the disc into the surrounding air. They were developed in the early 1900s. Because disc brakes provide stable braking force, they are widely used in trains, automobiles, aircraft and industrial machinery.