The Marvels and Limitations of Japan’s Shinkansen (Part 4): Starting from the Tracks

We are discussing the weaknesses of Japan’s Shinkansen. Last time, we focused on “maximum operating speed,” but this time, it is about the “weakness of the tracks.”

There are various obstacles that must be overcome to raise the maximum operating speed of the Shinkansen, such as noise pollution. Unlike countries like France, which are hidden agricultural nations with few large elevations, Japan’s narrow and rugged terrain imposes considerable constraints. While leaving urban areas like Tokyo or Osaka, the view from the window might show peaceful rice paddies… however, there are residential homes along the Shinkansen line, making the noise problem serious. Thanks to daily research efforts, we have successfully achieved both speed increases and reduced noise levels. For further acceleration, however, we must clear strict noise standards established back in the 1970s when Japan was a pollution powerhouse. We hope that the necessary standards can be met for the Hokkaido Shinkansen extension to Sapporo, allowing operation at 360 km/h.
To slightly deviate from the topic, the fundamental issue is that the track design of the Japanese Shinkansen itself has flaws. Over 50 years ago when the Tokaido Shinkansen opened, high-speed rail exceeding 200 km/h was an unknown concept. In winter, areas around Sekigahara often experience heavy snowfall, and there are frequent instances where the Shinkansen must slow down due to snow accumulation, causing delays. Unlike the Tohoku or Joetsu Shinkansen lines which run through heavy snow zones, the Tokaido Shinkansen cars are not resistant to snow. Therefore, they use sprinklers to spray water on the tracks to melt the snow. You might hear voices saying, “Isn’t that okay? There’s no need to slow down.” But actually, there is a problem with the “water” sprayed by those sprinklers. The Tokaido Shinkansen was built using a method called “embankment construction,” where fill material was placed on top of the ground. Gravel, known as ballast, was laid on top of that embankment, and then the tracks were laid over the gravel. Because spraying large amounts of water to melt snow could cause the embankment to collapse, they cannot spray much water, forcing them to reduce speed to a safe level. This is arguably an inherent drawback stemming from its status as the first high-speed railway. Of course, other Shinkansen lines built since the Tokaido line have learned from this experience and introduced methods that strengthen the subgrade, such as concrete viaducts or slab track, which fixes the tracks with concrete instead of using ballast (gravel).