JR East has introduced the “Shinkansen Early Earthquake Detection System” for the safe operation of the Shinkansen, a system that detects earthquakes promptly and stops the trains in an emergency.
Based on research results from the Railway Technical Research Institute, the process of estimating the earthquake scale after earthquake detection has been improved, and verification by the JR East Research and Development Center has made it possible to perform an emergency stop earlier than before. All Shinkansen seismographs (135 in total) will be recovered and put into service in March 2024.
The Shinkansen Early Earthquake Detection System is an emergency shutdown of the Shinkansen line by stopping the transmission of power from the seismographs to the substations based on the seismic motions observed at each seismograph. The system uses both the initial microtremors (P-waves) and major tremors (S-waves) observed, thus making the emergency shutdown earlier and more multiple.
While the S-wave detection system is designed to stop the train based on the amplitude of the S-wave, the P-wave detection method, which propagates faster than the S-wave, estimates earthquake parameters (epicenter distance, epicenter direction, and earthquake scale) from the observed P-wave and stops the bullet train before the S-wave reaches the emergency stop range according to the estimated magnitude.
The magnitude is known to be proportional to the magnitude of the P wave amplitude, but since the amplitude varies from moment to moment even for the entire P wave, the magnitude is estimated every second.Although the amplitude of the P wave generally increases with time, the coefficient in the estimation equation has been assumed constant regardless of time.
By changing the coefficients of the estimation equation with time in 1-second increments, the accuracy of the estimation from 1 to 4 seconds after P-wave detection has been improved, and values closer to the actual magnitude can now be estimated more quickly.
In the course of studying future earthquake countermeasures in response to the confidence off the coast of Fukushima Prefecture that occurred on March 16, 2022, we verified the results of 13 earthquakes that caused emergency shutdowns due to P-wave detection over the past three years. The improved system was found to reduce the time from P-wave detection to transmission shutdown by an average of 2.6 seconds, compared to 3.9 seconds for the current system.
© Source travel watch
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