No one in the world likes to be shaken by earthquakes. And since the Shinkansen operates at high speeds, readers may be wondering, “What would happen if an earthquake hit while I was on the Shinkansen?” What would happen if an earthquake occurred while we were on the Shinkansen? In this issue, we will discuss “earthquake preparedness” for the Shinkansen.
Seismographs detect earthquakes and stop power transmission.
The Shinkansen has a system that automatically stops trains when seismographs detect an earthquake. There are many possible ways to automatically stop a train, but the method adopted was to stop the transmission of power to the overhead lines.
Along the Shinkansen lines, there are substations at intervals of several tens of kilometers, where power received from the power company is converted to single-phase 25,000 V AC and sent to the overhead lines (strictly speaking, trolley lines). The theory is that seismographs can be installed at the substations to stop the transmission of electricity when a tremor is detected. If the power transmission is stopped, there will be no power source to run the trains.
However, this means that power transmission will not stop unless an earthquake occurs at or near the location where the substation is located. Then, the power transmission would be stopped after the shaking started. Therefore, seismometers were installed at remote locations. When a seismometer at a remote site detects a tremor, it immediately sends a command to the substation to stop transmission. The vehicles are equipped with a system that automatically applies the brakes when it detects that the transmission of power to the overhead lines has stopped.
For example, in the case of the Tokaido Shinkansen, in addition to seismographs along the line, distant seismographs are deployed over a wide area from the northern Kanto region to the Awaji Island area. In addition, the JMA’s earthquake early warning system and information from the National Research Institute for Earth Science and Disaster Prevention’s undersea earthquake observation network are also being used.
When an earthquake occurs far away, the electrical signals that send information from the seismographs are much faster than the speed at which the seismic waves are transmitted. Therefore, the logic goes that if the transmission of electricity is stopped ahead of time, the seismic waves can be slowed down sufficiently before they reach the bullet train tracks.
So what happens when such a system actually works? From the passengers’ point of view, first of all, the interior lighting will be turned off and only the emergency lights will be on. This is because when the power transmission to the overhead lines stops, the low-voltage power supply for the interior lighting is also interrupted. Emergency lights are powered by storage batteries, so they can be used even in the event of a power failure. These emergency lights are designed for such situations.
With that, the vehicle begins to slow down. Of course, the brakes are applied more harshly than normal, but nothing happens to cause the wheels to lock up and scrape the rails. If that were to happen, the wheels would scrape and create a flat area (called a flat). So “it feels like you are slowing down, but in fact you are slowing down faster than normal.
The author was once on a Tohoku Shinkansen train when it encountered an earthquake in Fukushima Prefecture. The train came to a stop in the Fukushima Tunnel, but after safety checks were made, power resumed shortly after and the train started running again, so it did not become a fatal standstill.
© Source travel watch
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