Feature Evolution of Railway Technology JNR’s Choice of Traction System—From Loco-hauled to Multiple-unit Trains Kenji Inayama by making innovative changes to some Early beginnings Introduction existing railway technologies. The In the late 1940s, a number of railway innovations and improvements were engineers began suggesting that In Japan, most long-distance passenger reflected especially in rolling stock, railways should start long-distance trains use the distributed traction system track, electric power supply systems, express electric passenger services. with powered cars carrying passengers. and signalling. This article focuses on One proponent of this idea was Hideo By contrast, in Europe, the USA and one technical development adopted for Shima (1901–98) who later became elsewhere, loco-hauled unpowered the Tokaido Shinkansen—rolling stock. known as the father of the Tokaido carriages are dominant, although adapted As explained above, most long-distance Shinkansen. As WWII drew to a close, multiple units are being tested by some passenger trains are electrical multiple he began basic research in the field, railways. In other words, the motive units (EMUs). This is such an obvious hoping to play an influential role in power is dispersed among the cars of fact today that one might think that the developing high-speed, long-distance the train set. Japan’s high-speed trains shinkansen designers would have electric passenger services in Japan. are all EMUs while European high- chosen the EMU model right from the Within a few years of the war’s end, the speed trains are basically loco-hauled. start. However, when the shinkansen newly formed JNR began an ambitious The design concepts are very was being designed in the late 1950s, reconstruction plan and Shima’s vision different—the shinkansen is powered most long-distance passenger trains in was to develop efficient long-distance by electric motors mounted in multiple Japan, Europe, the USA and elsewhere electric passenger trains for the new locations, while the TGV and ICE use a were loco-hauled. Until the 1950s, the network. locomotive to haul unpowered cars. very idea of developing an EMU train However, electric trains of the day Japan’s Tokaido Shinkansen was was considered quite revolutionary. suffered from uncomfortable ride opened in October 1964 to increase So why did Japan choose the EMU as characteristics caused by vibration and passenger capacity in the Tokyo–Osaka the model for the shinkansen? The Shima established the High-speed corridor because the Tokaido main line most-commonly cited reasons are Bogie Vibration Study Group in had reached its limit. The new line had lighter axle load, better acceleration December 1946 to find a solution to a maximum operating speed exceeding and deceleration, better braking, and the problem. 200 km/h, the fastest in the world at better operating efficiency. These The group identified a number of that time. By dramatically increasing advantages were recognized as electric factors and subsequent research speed, Japanese National Railway (JNR) train technology improved. As a result, focused on development of vibration- boosted demand for rail travel and the EMUs were soon running longer free bogies. This development made it shinkansen became an important distances at high operating efficiency possible to develop high-speed long- revenue source for JNR just as its and JNR’s decision-makers realized the distance electric trains running on financial situation was deteriorating. good sense of using them for long- narrow-gauge track. The shinkansen was so successful that distance passenger services. This In 1948, Shima became Director it motivated countries like France and article focuses on the background General of the Rolling Stock & Germany to build high-speed railways. against Japan chose the EMU for most Mechanical Engineering Department in Before the shinkansen, pessimists had of its passenger trains. charge of rolling stock development. predicted a slump in rail travel with Soon after, the department published passengers flocking to planes and motor Requirements for Electrification of vehicles instead. The Tokaido The Series 80 Shonan Densha Japan’s Government Railways, setting Shinkansen proved them wrong and forth a long-term plan for high-speed opened the way to new possibilities in This section describes the development electric train development. The report railway development. The so-called of the Series 80 Shonan Densha, which indicated the intention to promote ‘bullet train’ revolutionized the idea of is generally regarded as the grandfather electrification for medium-distance high-speed rail travel. of long-distance, high-speed electric trains serving large urban centres and In addition to building the Tokaido trains in Japan because it established for long-distance trains on the Tokaido Shinkansen to boost capacity between the realization in JNR that the future of main line between Tokyo and Osaka. Tokyo and Osaka, a second reason was long-distance passenger rail travel lay This plan led to the development of the to create a new, high-speed rail system with electric trains. Series 80 Shonan Densha. 40 Japan Railway & Transport Review 27 • June 2001 Copyright © 2001 EJRCF. All rights reserved. Development background Electric locomotives were being used to haul local passenger trains (known as Shonan Trains) between Tokyo and Numazu (126.2 km southwest of Tokyo) on the Tokaido main line. In the late 1940s, rush-hour commuters were crammed into carriages and there was a strong desire to cut the overcrowding by increasing the capacity. The government railways began looking at ways to increase capacity and Shima pushed for introducing EMUs, saying that the more-efficient operations (faster turnaround, etc.) would increase capacity. There was some opposition because EMU trains vibrated excessively and ride comfort would be far too low for a run of more than 100 km. However, increased capacity won out against comfort and the decision JNR’s long-distance Series 80 Shonan Densha (S. Kubo) was made to electrify the system. Rolling-stock development began in 1948 and was completed in 1950. The responsible for developing passenger division to develop the motive power designers soon realized that the carriages and freight wagons. This parts, such as motors and bogies, and carriage interiors would need at least separation of responsibility may seem for the latter division to develop the the same standards of comfort as unusual because EMUs and loco- body and fittings. This overlapping conventional carriages hauled by hauled carriages both carry passengers. responsibility changed the course of locomotive on long-distance runs. It However, officials at government EMU development and underlines the was hoped that the new design would railways at that time saw EMUs as quite fact that the Series 80 was a unique type be adapted for high-speed, long- different from loco-hauled carriages of train for its day. distance services creating an because the respective design and incentive to produce advanced operations technologies were different. Evolution of Series 80 bodies and bogies. Assigning development of EMUs to the The first units of the Series 80 left the The new Series 80 EMU was to be division that developed locomotives works in January 1950 and almost quite different in operation and reflects how the government railways immediately began carrying passengers technology from the existing electric viewed EMUs at that time. on local services between Tokyo and trains and its development required Although the Series 80 was to be an Numazu in March. Although the EMUs different organizational arrangement EMU, at the same time, it would increased capacity as planned, from previous rolling stock. consist of passenger carriages. The passengers were subjected to frequent Responsibility for rolling-stock question was whether the Series 80 breakdowns. With hindsight, this is not development within the Rolling Stock should be considered electric power surprising because the technology was & Mechanical Engineering Department cars. If so, the Motive Power Unit new and trial runs had only been was divided between the Motive Power Division should develop them. Or conducted for a few weeks before the Unit Division and the Passenger and should they be considered passenger trains entered service. Freight Car Division. The former was carriages? If so, the Passenger and As a stopgap to relieve the problems, responsible for developing locomotives Freight Car Division should develop some commuter services were returned and EMUs, while the latter was them. The solution was for the former to loco-hauled trains. This gave the Copyright © 2001 EJRCF. All rights reserved. Japan Railway & Transport Review 27 • June 2001 41 Evolution of Railway Technoloty designed specifically for high speeds and long distances—the Series 151 Kodama (Echo). JNR Electrified limited express services In the mid-1950s, JNR was proceeding with electrification of the entire Tokaido main line (556.4 km) but the question remained about what type of train should be used for the fastest limited express services when the electrification was completed. Also, what should be done with the existing Tsubame and Hato loco-hauled limited expresses? Despite the advances in long-distance passenger services between Tokyo and Numazu demonstrated by the Series 80 EMU, JNR still held fast to the conservative idea that loco-hauled trains were best for long-distance and limited express services. Thus, limited Odakyu’s Series Deha 3000 SE Romance Car (S. Kubo) expresses on the Tokaido main line were still hauled by locomotives even railway time to improve the rolling Nagoya and Osaka (190.4 km). In October after the line was fully electrified in stock, and breakdowns were soon 1957, Series 80 EMU express services November 1956. occurring less frequently, proving that nicknamed Tokai (Tokyo–Nagoya) and Hiei In 1957, JNR decided to add new the new EMUs could offer services on (Nagoya–Osaka) were inaugurated. limited express trains to the Tokaido schedule. The newly established JNR The new EMU local expresses were main line.