Sakuragichō accident (Japanese: 桜木町事故) was a train fire that occurred at around 13:45 on April 24, 1951, within the grounds of Sakuragichō Station on the Keihin Line (now the Negishi Line), a branch of the Tōkaidō Main Line of the Japanese National Railways, in Yokohama, Kanagawa Prefecture. Because the doors would not open, many passengers were unable to escape, resulting in a large number of casualties. Although it was not caused by a criminal act, it was also called the Sakuragichō Incident. After this accident, the installation and labeling of emergency compressed-air door release devices (emergency door cocks) became mandatory on passenger cars, including those with automatic doors, and the law was revised so that passengers could open the doors manually in an emergency.
Accident overview
On the up line within the grounds of Sakuragichō Station on the Keihin Line, a worker who was replacing the insulators of the overhead wire accidentally dropped a spanner, and as a result the up line's overhead wire was not secured and was sagging downward. Meanwhile, the Keihin Line's down train 1271B (a 5-car set of Series 63, which was running 9 minutes behind its scheduled timetable) crossed over from the down line via a switch and entered the up line, and the pantograph of the leading car became entangled with the sagging overhead wire of the up line. The motorman hurriedly attempted to lower the pantograph, but the pantograph of the leading car was damaged, causing the wire to contact the car body. An electrical short circuit then occurred, producing intense sparks that ignited the flammable paint on the roof, and fire began from the wooden ceiling. As a result, the leading car, Moha 63756, was completely burned out and the second car, Saha 78144, was partially burned, and the accident was recorded as a major disaster with 106 dead and 92 seriously or lightly injured.
The windows of the accident cars had a three-tier structure with the middle section fixed, and the height of the openings was only 29 cm, making escape extremely difficult. Because a short circuit was occurring, the automatic doors did not operate, and since neither the crew nor the station staff knew the location of the emergency cocks, attempts to open the doors manually from the outside were also not possible. The motorman tried to rescue passengers through the connecting doorway between the cars that had been cut off from power, but because the connecting doorways of the cars at that time were not intended for passengers to pass between cars, the hinged doors were locked from the outside. The connecting doorway of the second car was eventually opened, but the first car's doorway could not be opened due to the pressure of passengers trying to escape. As a result, passengers in the first car had no escape route other than breaking the windows, which further increased the number of casualties. At the time of the accident, the overhead wires near Sakuragichō Station were supplied with power from the Yokohama Substation and the Tsurumi Substation. The Yokohama Substation's high-speed circuit breaker operated and was able to cut off the power supply, but the Tsurumi Substation's high-speed circuit breaker did not operate, and electricity continued to flow into the overhead wires for about five minutes, which further intensified the fire.
Causes of the increase in damage
The Series 63 electric multiple unit involved in the accident was manufactured under what is known as "wartime design," in which important safety components were omitted or crude substitutes were used. While the use of many flammable materials was a feature shared with prewar cars, the Series 63 used many highly combustible materials, such as flammable paint and plywood ceiling linings, and its non-combustible construction was inferior even to prewar cars.
In addition, the Series 63 had poor-quality electrical wiring design (outdoor wiring that should normally be covered with insulating sheathing and protective steel tubing was instead exposed bare wire supported by insulators, and some indoor wiring was exposed inside the car without protective covers), and some of the safety equipment needed in the event of a current short circuit was also omitted. As a result, the structure was prone to ignition when electric current from the overhead wire flowed into the car body. As evidence of this, even before this accident, small-scale smoke and fire incidents occurred routinely even without external factors (in this accident, the cutting of the overhead wire), and in severe cases the car bodies were burned out and written off after accidents.
Furthermore, the windows of the Series 63 had three tiers for the purpose of improving ventilation and compensating for a shortage of glass, with the middle section fixed, so escape was impossible. The common view is that if the windows had been two-tiered, as on cars before the Series 63, or if the three-tier windows had a movable middle section, the openings would have been larger, making escape possible and reducing the number of victims. Regarding the doors, after the Chūō Main Line passenger fall accident of June 4, 1946, there was progress in replacing wooden doors with steel doors as a reflection on that incident, but together with the inadequate labeling of the door cocks, this ultimately became an unforeseen problem.
The connecting doorways at the ends of the same cars also opened inward on hinges rather than sliding. At that time, electric multiple units, which were the means of short-distance transport, were not equipped with the same kind of connecting passageway (with a bellows-type cover) as passenger coaches, and passenger movement between cars had not been considered. As a result, due to the pressure of extremely crowded passengers, the doors could not be opened and escape was also impossible.
As a ground-side factor, it can be pointed out that the Tsurumi Substation did not immediately stop the supply of power.1 The Yokohama Substation, which was closest to the site, detected the fault current and its circuit breaker operated instantly to stop the power supply, but the circuit breaker at the Tsurumi Substation, which was farther away, did not detect the fault current because of its distance, and leakage from the Kawasaki Substation continued. Normally, if the circuit breaker at the Yokohama Substation operates, leakage from distant locations does not occur. However, because two of the four circuit breakers had been removed to restore the Shiodome Substation after a fire that had occurred before this accident, the leakage circuit became T-shaped, and power supply from the Kawasaki Substation could not be stopped. At that time, substations were unmanned and had no interconnection or remote control devices, so in the event of an accident, the shutdown of adjacent substations depended on telephone communication. Triggered by this, a DC feeder fault selection device that detects fault current based on the rate of change of current (I) was developed.2
Additionally, although not a direct or indirect cause of the accident, the fact that the ticket gates at Sakuragichō Station at that time were located at the edge of the platform caused passengers to concentrate at the leading car, which was also a factor in the increase in casualties.
Countermeasures after the accident
At that time, the National Railways took quick countermeasures, such as posting notices indicating the locations of emergency cocks on the car bodies of all cars a few days after the accident and affixing notices inside the cars describing the location of the cocks. For the electric multiple units designed during the war, it carried out emergency modifications, including first applying fire-retardant paint inside the cars, reinforcing pantograph insulation, and installing connecting passageways and connecting nets in the cut-off sections (completed within 1951). Subsequently, it carried out thorough structural improvement work, including converting the car interior ceilings to steel plate, widening the connecting passageways, and making the three-tier windows fully movable. The structural improvement work for the approximately 800 target cars was completed in just two years. This can be said to illustrate the impact this accident had on society.
In addition, as a result of the structural improvement work described above, the Moha 63 electric multiple units were reclassified as Moha 73 (control car), Moha 72 (intermediate car), and so on, and were used until the end of the National Railways era. For details, see the "Modifications" section of the National Railways 72 series electric multiple unit.
Trial
Those responsible for the accident were indicted. A total of five people, including the worker who dropped the spanner, the signal staff of Sakuragichō Station, and the crew of the accident train, were sentenced to imprisonment with labor for terms ranging from six months to one year and ten months.
Social impact
Yukio Kagayama, the second president of the National Railways, resigned to take responsibility for the accident.
The National Railways had started a professional baseball team, the "National Railways Swallows" (now the Tokyo Yakult Swallows), in 1949, and afterward was devoting itself to recovery, including introducing new types of rolling stock such as the Series 80 and Series 70 electric multiple units and seeking to revive train services that had been abolished during the war, such as limited express trains, dining cars, and sleeping cars. Because the accident occurred during this period, the shock within the National Railways was great, and the media harshly criticized it, with statements such as "If you have time to take part in professional baseball, carry out the maintenance of the defective electric multiple units first!"
Hideo Shima, who was one of the members of the team that developed the Series 80 electric multiple unit and who was serving as director of the National Railways Rolling Stock Bureau at the time, resigned to take responsibility for this accident and was away from railway engineering until 1955, when he returned at the request of Shinji Sogo.
At that time, the "Sazae-san" series serialized in the Asahi Shimbun also had an episode that took this incident as its subject.
A memorial monument for the accident stands at Sōjiji Daihonzan, a Sōtō Zen temple in Tsurumi Ward.
References
- Nakagawa Koichi, "The Relationship Between the Sakuragichō Accident and the Moha 63 Series"
Denki Sharyo Kenkyukai, Tetsudō Pictorial, January 2005 issue, No. 756, pp. 64–69
- Asahara Nobuhiko, "Which of Saha 78144 and 188 Was the Accident Car? A Mystery in the Sakuragichō Accident Report"
Neko Publishing, Rail Magazine, August 2006 issue, No. 275, pp. 114–115
Notes