Introduction:
The Keihin-Tohoku Line is a common name given for the JR East’s EMU train service running over a route between Omiya-Ueno-Tokyo-Yokohama-Sakuragicho-Ofuna, a long run of 81.2 km across the three prefectures of Saitama, Tokyo and Kanagawa. The service length of 81.2 km is the longest among commuter EMU services in JR East’s territory. There are 46 stations on the route including historic Ueno, Tokyo, Shimbashi, Kawasaki, Yokohama and Sakuragicho. It takes more than two hours to travel through the whole length. Its formal name is the Tohoku Line between Omiya and Tokyo, the Tokaido Line between Tokyo and Yokohama, and the Negishi Line between Yokohama and Ofuna. The nature of the service is local trains covering every intermediate station in the Tokyo metropolitan area and its suburban areas, particularly on the Omiya to Ueno and Tokyo to Yokohama sections, as opposed to longer-distance trains of the Tokaido Line and Tohoku Line that do not stop at most of these stations. The southern section of the service is along the Negishi Line, diverging from the Tokaido Main Line at Yokohama, which goes through Yokohama’s downtown area, heavy industrial area, and then suburban residential area. In contrast to the historic background of the Tokyo to Sakuragicho section, the Negishi Line section is quite new, having been extended in the 60s and the 70s. Now, the line is served solely by a fleet of sleek 10-car 209 series stock, including some sets of a new version of the series numbered in the 500s. However, the old 72 series, ex-JNR’s most common equipment used for urban EMU service in the Tokyo area, was dominant on the entire service for a long time after the War until modern stock of the 103 series was introduced around 1965.

Background:
The Keihin-Tohoku Line may not seem to have a particularly unique service compared to other JR’s Tokyo area services, but before the WWII, it used to be the most prominent electric car service among the Shosen-densha (Note1). It was always on this line when newly developed stock was put in service. It was served even with a dual-class car (second class and third class), half of which was a second class section, which was never seen on other similar lines. The origin of the Keihin-Tohoku Line service dates back to the electric car operation between Tokyo Central Station and Takashimacho station in Yokohama (Note2), which was commenced by Tetsudo-In (Note3) in December 1914. The service was intended to provide short-distance, frequent service between Tokyo and Yokohama, on which passenger demands were drastically increasing. The commencement of the service was dramatic enough with the usage of the newly built double track segregated from the Tokaido Line’s long distance train tracks also coinciding with the completion of the new Tokyo Central Station (Note4), reached by extended elevated tracks from Shimbashi. Actually, the current double track infrastructure between Tokyo and Yokohama was completed at that time. The Tetsudo-In was already serving electric car operation on the Chuo Line between Manseibashi (Note5) and Nakano, and the Yamanote Line between Gofukubashi (Note6) and Ueno, but unlike these lines, the new service was epoch-making enough in the technical aspect, with 1200V DC electrified catenary and pantographs for drawing power as opposed to trolley wires and poles of the already existing systems. The new stock put in service used a car body upgrading in length and height, and operated in two- or three-car formation in Electric Multiple Unit (EMU) control mode, with propulsion power by 85 kW traction motors on upgraded bogies. Despite these technological novelties, the service was reportedly not very successful with many troubles encountered, followed by an early service suspension. The railway history tells that it was the May of the next year when the service resumed as a result of the completion of the improvements concerning the technical issues.

The service segment was extended southwards in December 1915 up to the current Sakuragicho when the main Yokohama station moved to the former Takashimacho from Sakuragicho (Note7). In November 1925, as the elevated tracks between Tokyo and Ueno were completed, the Toyko-Sakuragicho ‘Shosen Densha’ service was extended northwards to Ueno. This was a quite historic milestone for the government railway’s EMU service in the Tokyo area with the commencement of the circular operation on the Yamanote Loop Line. The Chuo Line’s electric car service was converted to just between Tokyo and Nakano, ceasing through operation with the Yamanote Line (Note8). The service was soon further extended northwards to Tabata one month later. The Akabane extension was completed in February 1928, followed by the full opening of the service as far as Omiya in September 1932.

The service remained in this route form for a long time through the War period. After the War, evolution took place at the southern end of the line in Yokohama. The construction of the Negishi Line progressed southwards from Sakuragicho, reaching Isogo in May 1964. The Yokodai extension was completed in March 1970. The line finally reached Ofuna in April in 1973, completing the current entire service route.

• Note1) Shosen-densha signifies ‘the government railway’s electric car services’, dubbed after Tetsudo-Sho (Railway Ministry).
• Note2) Takashimacho was located between the current Yokohama station and Sakuragicho station, near the current Tokyu Toyoko Line’s Takashimacho station.
• Note3) Testdudo-In is the former name of Tetsudo-Sho. At his period, the service was called ‘Insen-densha’.
• Note4) The current Tokyo station.
• Notw5) Manseibashi is an abandoned station located between Kanda and Ochanomizu, but the station structure still remains as the Transportation Museum. The ruin of the island platform at this station can still be seen on the track above the Transportation Museum even nowadays.
• Note6) Gofukubashi is an abandoned station located between Tokyo and Yurakucho.
• Note7) The process of the location change of Yokohama station is complicated. The current Yokohama station is at a third location after moving from Takashimacho.
• Note8) Before that time, the Yamanote Line was served by through operation with the Chuo Line encompassing Nakano-Shinjuku-Kanda-Shinagawa-Shinjuku-Ikebukuro-Tabata-Ueno, utilizing the already completed elevated tracks between Tokyo and Kanda.

Change of Line Name:
The service was first called ‘Keihin sen’, an abbreviation of Tokyo-Yokohama. As the service extended northwards over the Tohoku Line section, the line seems to have called as the ‘Tohoku-Keihin sen’ for a particular period, but the current ‘Keihin-Tohoku sen’ was finally established around the War period. However, the historic name of ‘Keihin sen’ is still heard even nowadays through the platform announcement of the Keihin-Tohoku Line at Tokyo station.

Rolling Stock Operated on the Keihin-Tokoku Line:
Among the rolling stock used to run on the Keihin-Tohoku Line, the most distinctive one was the Deha 43200 series introduced in 1922. This equipment was powered with four 150HP traction motors and featured cross-seats for the first time on electric cars of the government railway (a large cut-away model of this series is still exhibited at the Transportation Museum, and one can learn through this model that its appearance including the front appearance leads to that of the typical modern Shosen-densha stock). At the beginning of the Showa era around 1925, the technology of the electric cars made significant progress as to performance and reliability, with the improvement of multiple unit control and the air brake system. Especially, the introduction of pneumatic-operated door engines was innovative enough, allowing simultaneous opening and closing of all doors on a train set, bringing a great advance on passenger safety. The steel-made car body was first adapted on the Deha 73200 series (later Moha 30) in 1925. In 1929, the Moha 31 featured a integral curved roof for the first time rather than the former double roof structure common to rolling stock in those days. The progress was followed by cars of cross-seats of the Moha 32 series in 1930 and 20m length class cars in 1931. Around 1935, the semi-streamlined Moha 60 series appeared. The Keihin-Tohoku Line was served with this stock together with its variants including the Kuha 55 and various types of dual-class cars for a long time until the 63 series was introduced during the War period. After the War, the 63 series continued to be mass-produced to meet rapidly increasing passenger demands that pervaded not only the Keihin-Tohoku Line but also other EMU-served commuter lines in the Tokyo area, the Yamanote and the Chuo lines. The poor quality of this series due to the frugal War time design surfaced when a fire broke out on a 5-car train set of this series at Sakuragicho in April 1949, killing 106 passengers with 92 seriously injured (this notorious accident is known as the Sakuragicho incident). Learning a lesson from this incident, this series was totally improved soon from the safety aspect, and all became the 72 series.

Various Features:
The symbol colour of the Keihin-Tohoku Line is blue, and stainless steel built 209 series cars in the fleet are all liveried with two blue stripes below and above the windows. This symbol colour was established when 103 series was first introduced in 1965 following the Chuo Line’s orange and the Yamanote Line’s green.

In terms of traffic direction, since the line runs through Tokyo station and Ueno station, the operation is classified as North-bound and South-bound, as opposed to Up and Down common among other railway lines in Japan. The Line’s operation is most frequent between Akabane and Kamata, every two minutes at the peak time, with the service patterns comprising Omiya to Kamata, Omiya to Tsurumi, Omiya to Sakuragicho, Omiya to Isogo, Omiya to Ofuna, Minami-Urawa to Ofuna and Akabane to Ofuna. There are a few trains which are terminated at Higashi-Jujo and Ueno North-bound, and Higashi-Kanagawa South-bound in the late evening. The southern section in Yokohama from Higashi-Kanagawa is also served by through trains coming from the Yokohama Line. Most of the Yokohama Line through trains are terminated at Sakuragicho, with a few going as far as Isogo and Ofuna.

An interesting part of the Keihin-Tohoku Line is between Tabata and Shinagawa in the central part of Tokyo, where the Yamanote Line’s circular service parallels. This segment consists of two double tracks dedicated to respectively the Keihin-Tohoku and Yamanote Lines. Between Tabata and Tamachi, the Yamanote Line uses the inner two tracks while the Keihin-Tohoku Line runs along the outer two tracks so that both services in the same direction run parallel to each other. At each station on this section, two island platforms are sandwiched by both line’s tracks going in the same direction, providing an easy transfer between both services to passengers. This convenient strategy was first planned just after the full service opening between Sakuragicho and Omiya in 1932, but due to hardship during the War period, the upgrading work was disrupted. It was in 1956 when the twin double-track structure was finally completed, resolving a bottleneck in increasing both services’ operation capacity. Another factor helpful in realizing this strategy were two crossovers between the two services located north of Tabata and between Shinagawa and Tamachi, both of which were completed much earlier, in 1927.

With the advantage of the Yamanote Line running parallel between Tabata and Tamachi, the Keihin-Tohoku Line trains are operated as a rapid service on this segment during the day time between 10:00 AM and 15:00 PM. During this time, the Keihin-Tohoku Line trains stop only at Ueno, Akihabara, and Tokyo. This rapid service was introduced in March 1988 a little while after the JNR was privatized. This service has become established these days, although there was some confusion in the early stage. However, you need to be careful when you travel to an intermediate station from the north or south outside this service segment during the off-peak time.

Depot:
Nowadays, all stock in the Keihin-Tohoku Line fleet is concentrated at Urawa depot, but they used to be distributed at four depots, Kamata, Higashi-Kanagawa, Shimo-Jujo and Urawa. There are Y tracks for return operation at Ueno, Kamata, Tsurumi, Sakuragicho and Isogo. Sidings for overnight layover are at Shimo-Jujo (depot), Kamata (depot), Higashi-Kanagawa (depot), Isogo and Hongodai. Crews are based at those depots of Urawa, Shimo-Jujo, Kamata and Higashi-Kanagawa. Crew changes are seen at Minami-Urawa, Shimo-Jujo, Kamata and Higashi-Kanagawa.

Signal and Freight Work:
The Keihin-Tohoku Line uses a cab-signaled ATC system, which was introduced by 1984 (now the line is under process of the replacement of the ATC with a more advanced system). No wayside signals are seen alongside the track on the segment north of Sakuragicho except shunting signals. The Sakuragicho to Ofuna section is installed with wayside colour light signals, because freight trains share the track. Particularly up to Negishi from Sakuragicho, fairly active freight work is seen, because of the existence of an oil refining complex at Negishi and a freight branch connecting to Honmoku freight station of the Yokohama Waterfront Railway situated close to Yokohama Port. Tanker trains and intermodal container trains rumbling along the elevated track in downtown Yokohama are an interesting feature for railway enthusiasts.

Recent Major Milestones of the Keihin-Tohoku Line:

• 1965: 103 series was introduced.
• 1972: Obsolete 72 series was completely withdrawn. 10-car formation was fully achieved with the 103 series along with five 10-car 101 series sets which were supplementarily allocated.
• 1974: New version of the 103 series fitted with air-conditioners and on-board ATC equipment began to be introduced.
• 1984: The introduction of the ATC system was completed on the entire service length.
• 1992: The prototype of the 209 series was put in service.
• 1995: The mass-production version of 209 series was put in service.
• 1998: 103 series was completely withdrawn.
• 2001: A new version of the 209 series featuring a wider car body numbered in the 500s was put in service.
• 2007: E233-1000 series 10-car electrical multiple unit (EMU) enter service
• 2010: 209 series 10-car EMUs completely removed from Keihin-Tōhoku Line service

Summary:
I have long been a daily patron of the Keihin-Tohoku Line since I settled down in Yokohama with the start of my career. With this background, I have been seeing the evolution of this service through my daily rides. My ride is mainly on a southern section between Tsurumi and Yokodai, commuting for about 30 minutes. When I began to use this line, the rolling stock in use was 72 series, a reminiscence of old ‘Shosen Densha’ retaining dignity in its dark maroon livery with varnished wooden interior. In spite of the line’s glorious history, the status of the line around that time was rather declined against other major commuter lines, the Chuo Line and the Yamanote Line. The 103 series, categorized as the ex-JNR’s high-performance stock following the 101 series, came rather late to the Keihin-Tohoku Line after these other lines. The re-signaling with the ATC system was at the same time as the Yamanote Line, but its benefit was subtle for passengers, although it was quite innovative from the technological aspect. The introduction of air-conditioned stock also started several years later after the Chuo and Yamanote Line, although it was quite thankful in muggy summers.

No big changes are expected to occur for a while in the near future on the Keihin-Tohoku Line, but it will continue providing a quite good quality of service with neat rolling stock of 209 series as well as reasonable operation frequency.

Photos were taken by the author unless specified.

Photos were taken by the author in February 2002 unless specified.