Masayuki Nakao (Institute of Engineering Innovation, School of Engineering, The University of Tokyo) A multiple train collision occurred 350m east of the M ikawashima Station of JNR, involving a freight train on the outbound Joban freight line and passenger trains on the outbound and the inbound Joban lines. The primary causes were the train operators' red light running and a delay in the stationmaster's accident notification. After the initial collision between two trains, 160 passengers were killed and 296 were injured by the accident. Many of them    were  passengers o f t he ou tbound-train  who wer e w alking on th  e in bound  line to wards the Mikawashima Station after getting out of the train through doors opened using emergency handles. They were run over by an incoming train on the inbound Joban line.
1. Event
A multiple train collision occurred 350m east of the Mikawashima Station of JNR, involving a freight train on the  outbound Joban freight li  ne and  passenger trains on the  outbound and  inbound J oban lin es.  160 passengers were killed and 296 were injured in the accident.
2.
Course (Figure 1 and 2)
The  first  collision : At  21:36, a freigh  t t rai n 28 7 fr om the T ahashi Swi tchyard bou nd for Mito on the outbound Joban freight line was traveling to join the main line at  Mikawashima Station. The  freight train operator missed the red s ignal at t he main line (the freight line was to w ait for 2117H train on the main outbound passenger line to leave the station). At 21:36:30, the freight train broke through onto the safety siding. The signal connected to the safety siding activated the fail-safe device, preventing the freight train from  entering into th  e  main l ine, ho wever, the  loco  and first t anker wago n d erailed t o b lock t he  main outbound passenger line. The second collision : The 7-car passenger train 2117H bound for  Toride from the Ueno Station departed the Mikawashima Station at 21:36, 4 minutes behind schedule. At 21:36:40, the passenger train, which was traveling at 40km/h at that time, struck the derailed freighter. The first two cars derailed and blocked the main inbou nd pass enger lin e.  The  safety s iding prev ented  a d evastating colli sion, result ed i n o nly 25 injuries.  Passengers of th  e 2 117H  opened doo rs u sing em ergency  handles and st  arted walkin g on  t he inbound line towards the Mikawashima Station. The Mikawashima East Signal Station located 100m from the accident site had 2 operators, but they were too busy  confirming and reporting to their  manager about the accident to stop the departure of the next passenger train. The third collision : 5 minutes and 50 seconds after the second collision, the passenger train 2000H bound for Ueno arrived on the main inbound passenger line, ran over people escaping from the accident site and collided with the detailed 2117H. Its first car was smashed and its second cars through the fourth derailed, resulting in a to tal o f  160  lost l ives a nd 29 6 i njuries. T his  third  collision b rought d evastation t o  the accident. Figure 1. Mikawashima Station on the Joban Line [1] (The passenger line and the freight line join the main line at the Mikawashima Station.) Figure 2. Collision at Mikawashima: Sequence of Events [1]
3. Cause
The direct cause was the freight train operators' missing of a red signal. Although an automatic train stop device was not available at t that t ime to stop the train when the operators missed a signal, the safety siding functioned properly as a fa il-safe system for preventing a dev astating col lision. I t prevented the freight train from entering onto the main line. However, the freight train was traveling too fast to stop on the safety siding. It derailed to block the down passenger line. The collision of the outbound train 2117H with the freight train occurred 10 seconds after the freight t rain colli sion. Althou gh i t wa s a lmost impossible for the 2117H to avoid the acci dent, the accident itself was very small in scale injuring only 25 people. The safety siding saved lives and minimized damage caused by the accident. The  impact of  the a  ccident wor sened  when p assengers, witho ut  being i nstructed  by the tr ain  operators, opened  doors using emergency handles that w ere ins talled in response to  the Sakuragi-cho A ccident o f 1951 (passengers were trapped in the train cars and unable to escape from the train fire), and got off the train onto the railway track. The d elay i n stopping the next inboun    d train 2  000H  multiplied the   damage t o the   accident. T he stationmaster could have taken some action to stop departure of the 2000H in 5 m inutes and 5 seconds. However, the relay of information taken by the stationmaster and operators led to delay as shown in Figure 3, resulting in the multiple train collision and many casualties.
4.
Immediate Action
While it was essential to investigate the direct cause of this accident, a lot to considerations must be given to adequate immediate actions that should have been taken after the first collision occurred. Inadequate responses to  the accident, for example the passengers got off the tr ain onto  the r ailway tr ack without instruction from the train operators and the stationmaster failed to notify the station up the line as soon as the accident happened, led to the devastating accident.
5. Countermeasure
(1) An automatic train stop device (ATS) had been installed on all lines of the Japanese National Railways. The ATS activates the emergency brake when the train passes through a red signal. (2) The railway’s operation policy changed from “do not stop trains unless absolutely necessary” to “stop trains as soon as an accident happens regardless of its scale". To increase safety further, a train radio system was installed to enable direct communication between train operators and the center.
6. Summary
Considering the signaling system at that  time, it is  understandable that the outbound passenger train was unable to avoid co llision with the freight train der ailed missing a r ed signal. The multiple-train collision was due t o  the r ailway cr ew’s failure in stop ping de parture of the next inb ound  train  2000H. The t hird collision o ccurred 5+ m inutes after th e s econd co llision, wh ich s hould h ave g iven enough time fo r the railway crew to stop the next train. The safety plan was  ineffective be cause it di d not a uthorize the signal station operators to stop trains at their own discretion. The railway crew training was also insufficient.
7. Knowledge
When an accident happens, stop traffic first and then determine the accident scale. Operators should be adequately trained for emergency procedures and authorized to stop operation of their devices at their own discretion. In response to this Mikawashima accident, the railway implemented an operational policy of "stop trains as soon as an accident happens regardless of it s scale". However, 10 years later in  1972, this pol icy added devastation to the damage in the train fire in the Hokuriku Tunnel (a passenger train made an emergency stop in the tunnel).  Required emergency procedures differ depending on the accident's circumstances and an instruction manual cannot cover everything. Training must raise the safety consciousness of operators so that they can always give reasoned judgment even under unexpected circumstances.
8.
Background
On October 26, 1943 at around 18:40, a similar multiple train collision occurred near the Tsuchiura South Signal B ox  at t the T suchiura S tation on  the Jo ban l ine. Howev er, ther e was  little r eport on  the ac cident because of  the ti me ( during the war). The  Mikawashima acci dent ( the t hird  collision in p articular) ma y have  been preven ted, i f imp rovements  had been  made to  the  safety  plan  in  response t o  the T suchiura accident. The emergency door handles that brought a problem in this accident were installed after the train fire at the Sakuragi-cho Station on the Keihin-Tohoku line, which claimed many lives in 1951. At the Sakuragi-cho Station, the passenger train MOHA-63 touched a sagging overhead wire and sparks caused a disastrous fire. Among the passengers trapped in the train cars, 106 were killed and 92 were injured. The operators were unable to open doors because of short-circuits, and the window structures did not permit evacuation (the middle panel of the three-panel window was fixed to the frame). Some may argue that this improvement (emergency door handles) invited a large number of casualties, but we need to always remember the basic fact, that is, "railway tracks are for trains to run on, not for people walking on them”.