Heralding the Age of High-Speed Rail Transport Network Expands East and West High-Tech Operation Systems Supporting Exacting Operation Assuring Safety and Comfort

Assuring Safety and Comfort

As one exits at a Shinkansen terminal, an unfamiliar yellow train can sometimes be seen on the opposite platform. "Dr. Yellow," as this train is affectionately known, is a special type of Shinkansen that is used to inspect tracks and overhead lines along the Shinkansen routes. Running at the same speed as the Shinkansen passenger trains, Dr. Yellow inspects every stretch of Shinkansen track at least once every ten days, measuring and checking the condition of the overhead lines and tracks. If by any chance anything out of the ordinary is detected, this information is immediately relayed to a terminal at the track maintenance center responsible for that section, and a crew of maintenance technicians goes to the site that same night in a state-of-the-art maintenance car and sets to work. What's more, the data Dr. Yellow collects is analyzed in a "central equipment control processor," and the results become important references for use in managing maintenance activities. The tolerance for rail gauge is a mere three millimeters. If that is exceeded, not only is the quality of the ride affected, but a major accident could occur. The Shinkansen does not run all night to allow time for these kinds of safety inspections. Many Shinkansen employees are up all night performing these rigorous inspections to keep the tracks safe. The Shinkansen system is also ready to deal with challenges nature sometimes imposes—such as heavy snowfalls and earthquakes. In areas that experience heavy snow, Shinkansen tracks are equipped with their own sprinkler systems to keep snow from accumulating. To detect earthquakes, seismometers are positioned at intervals of 24 kilometers along all Shinkansen tracks; and where the Shinkansen runs along the coastline, they are placed under the sea. Great effort has been put into making sure that even the slightest bit of earthquake activity will be detected. Successfully pushing the Shinkansen to higher speeds has demanded the comprehensive technical savvy to simultaneously increase drive power and reduce weight, two diametrically opposed objectives. However, the underlying paradigm of transmitting force from wheel to rail to propel trains seems to come with an inescapable limitation: if speed is pushed too high, wheels begin to lose contact with rails, making it impossible to boost speed further. For the same reason, when brakes are applied at too high a speed, the wheels simply slip along the tracks. Currently, the maximum limit of commercial high-speed rail travel is 300 km/h. But the process of taking the Shinkansen beyond that threshold has already begun—with research into linear motor cars that employ magnetic levitation. Testing to bring this technology into practical application is proceeding at a rapid pace. Although we do not yet know the exact day that Japan's Shinkansen will once again herald a new age in rail transport, when it does, it will undoubtedly recapture the world's attention. The editors would like to thank East Japan Railway Company, for its cooperation in preparing this article. Title page photograph courtesy of M. Mashima Photo Office.

Dr. Yellow travels the Shinkansen tracks at the same speeds as the passenger trains, checking the condition of the overhead lines, rails, and signal equipment as it goes. The data thus collected is analyzed and then passed on to maintenance-unit terminals.

Aluminum Rail Cars: Lighter, Stronger Shinkansen cars were destined to become lighter over time. The first car in which aluminum was used extensively was the aircraft-like 300-series Shinkansen that appeared in 1992. The technique of using large-scale aluminum extrusion to create a single 25-meter aluminum car structure of the 300-series was a fundamental departure from previous design approaches and was a world-wide first. "Perhaps it's because train cars trace their origins back to covered wagons," says Shinji Sato, a manager at the Transportation Materials Market & Sales Dept. of Sumitomo Light Metal Industries Ltd., "but the approach has always been to attach some kind of sheet material to a frame. Following in this tradition, the first Shinkansen cars were built with frames, to which plates of steel or aluminum were affixed. But in the 700-series trains, which evolved from the 300-series, a radically innovative approach was adopted: the frame was dispensed with entirely and replaced by a two-layered 'double-skin' construction." Each layer of aluminum plating is 1.8 millimeters thick, which may not seem very confidence-inspiring; but is in fact, more than strong enough because the metal is extruded to form a single piece. The space between the inner and outer aluminum layers is filled with a special vibration-absorbing rubber, which is included in order to minimize both vibration and sound. Sato explains:"The thinness of the aluminum is the result of an all-out effort to lighten the cars to reduce the stress on track structures and the weak ground the tracks had to be laid on. Moreover, the lighter the cars, the quieter they are, which keeps noise levels down in heavily populated areas. On the other hand, the many curves on the Shinkansen lines demand a high level of carriage strength. In addition, trains pass each other at high speeds in tunnels and on bridges. Our view of the kind of strength required may be fundamentally different from the view in Europe. In any case, on railroads that impose sudden air pressure changes when trains pass through tunnels and by oncoming trains, the strength requirements are actually even higher than for aircraft bodies. The 700-series trains satisfy the dual requirements of lightness and strength. Just how much lighter are today's Shinkansen trains? The first Shinkansen cars 35 years ago weighed 20 tons, but the newest cars weigh only six —less than one third. Owing not only to the switch to an aluminum body, the lightening of the Bogie Trucks (wheel and axle assemblies), motors, and control equipment, have all contributed greatly to total weight reduction. Today, the development of linear motor cars is promising to bring the Shinkansen into a new era. "Beyond the need to build lightweight cars, linear motor cars present another challenge," says Sato. "Because they use magnetic levitation, we couldn't build them at all without using aluminum, because it does not carry magnetism. By using aluminum, we are able to build mag-lev cars that operate with a lower level of ambient magnetism than hospital hallways —a level that doesn't interfere with pacemakers." Sato adds that stainless steel cannot handle the stresses of travel at over 160 km/h; thus aluminum will continue to be indispensable to the construction of high-speed railway cars. The 700-series carriage and a cross-section of its aluminum body. Jointly developed by Central Japan Railway Company (JR Tokai) and West Japan Railway Company (JR West), the 700-series is characterized by its streamlined aerodynamic form. In the spirit its advanced appearance projects, the 700-series incorporates a number of innovations that once defied convention wisdom.

(Data collected January 2000)