The Keiyo Line (京葉線) is a railway line of East Japan Railway Company (JR East). Its main route runs from Tokyo Station along the Tokyo Bay coast, through Ichikawa-Shiohama and Minami-Funabashi, to Soga Station in Chiba city.
History
The line began as part of an older plan. The National Railways first planned a line linking Shiodome, Tsukishima, Harumi and Etchujima. That plan was replaced by a Tokyo Outer Ring Line. It would join five main lines in a ring about 20 km out from central Tokyo. One part of that ring, a line from the Shiohama yard in Kawasaki along Tokyo Bay to Kisarazu in Chiba, became the Keiyo Line. The Railway Construction Corporation (鉄道公団) built it as a metropolitan line. The line was first planned as a freight line and later changed to a passenger line. Before that change, a passenger link to the Yurakucho Line (有楽町線) was proposed for residents of Kaihin New Town. Most of the line was designed as elevated track for freight. Several freight branches were left unfinished or unused, and the Delta junction near Nishi-Funabashi is one remnant. The land set aside for future quadruple track was later used to widen Tokyo Bay Shore Road. The line was approved in stages. In February 1967 the Shiohama yard to Shinagawa-futo section was approved. In June 1971 the West Funabashi to Soga section was approved. In October 1973 the Tokaido freight line from Shiohama yard to Tokyo Freight Terminal opened. In March 1974 the West Funabashi to Tokyo Freight Terminal section was approved. On 10 May 1975 Soga to Chiba Freight Terminal opened as a freight line. In September 1978 West Funabashi to Soga was approved as a passenger line. In November 1980 the Chiba governor agreed to a longer period of temporary rail shipping of aviation fuel to the new Tokyo International Airport, and asked in return for early passenger service and a link to Tokyo Station. In July 1983 passenger service was approved from Tokyo Freight Terminal to West Funabashi, and for a Tokyo to Shin-Kiba section.
On 1 April 1987 East Japan Railway Company took over the line after the national railways were split up. Japan Freight Railway became the freight operator between Chiba Freight Terminal and Soga. On 21 January 1986 the track between Soga and Tsukawa signal station came into use, and the borrowed Kawasaki Steel private line was no longer needed. On 3 March 1986 passenger service began between West Funabashi and Chiba Minato (now Chiba Minato Station). Minami-Funabashi, Shin-Narashino, Kaihin-Makuhari, Kemigawa-hama, Inage-kaigan and Chiba Minato stations opened. On 1 December 1988 the Shin-Kiba to Minami-Funabashi section and the Ichikawa-Shiohama to West Funabashi section opened. This was the first use of ATS-P in JR. On 10 March 1990 the Tokyo to Shin-Kiba section opened, and the whole line was complete. Centralised train control (CTC) was introduced across the line. Rapid services began with the opening. On 16 March 1991 the limited express Wakashio and Sazanami were rerouted via the Keiyo Line.
The official route names changed as each part opened. The official main line is West Funabashi to Soga. The Tokyo to Minami-Funabashi section and the Ichikawa-Shiohama to West Funabashi section are branches. In daily operation, however, the main route is treated as running from Tokyo Station to Soga through Ichikawa-Shiohama and Minami-Funabashi. The official sections have not changed since the 1988 and 1990 openings, so the official records and daily operation now differ.
On 1 April 2000 Chiba Freight Terminal closed. On 2 December 2000 Japan Freight Railway became the freight operator between West Funabashi and Soga, and freight trains began running on the line. Freight trains from the Keiyo Rinkai Railway were moved to a route via Soga and West Funabashi. The Musashino Line trains were extended to Kaihin-Makuhari, and some rapid trains began stopping at Chiba Minato on weekdays. On 1 December 2002 the line had its first timetable revision that rewrote the whole schedule since opening. On 16 October 2004 Shin-Kiba was added as a stop for commuter rapid trains. In 2007 E331 series trains began running, and on 18 March 2007 some limited express trains began stopping at Kaihin-Makuhari. On 28 September 2006 a fire broke out at a substation inside Tokyo Station, and the line was closed in both directions for about half a day. Many passengers rushed to the Tozai Line station at Urayasu. On 30 July 2009 a 205 series train stopped between Shin-Kiba and Kasai-Rinkai-koen after an electrical short. A fire at the Etchujima substation then cut power, and the line was shut for about seven hours.
On 11 March 2011 the Tohoku earthquake stopped the whole line right after it struck. Services restarted the next day, but a special timetable ran for a while because of rolling blackouts. The E331 series left service on 16 January 2011, after about four years in use. On 28 November 2012 a fuse failed on a train between Futamata-shinmachi and Minami-Funabashi, and the whole line was suspended for four hours. On 16 March 2013 most morning rapid trains were replaced by local trains, except commuter rapid trains. Musashino Line trains also became local trains. On 25 September 2016 the ATOS train management system was introduced. It was the latest of the JR conventional lines inside Tokyo's 23 wards to get it.
On 18 March 2023 Makuhari-Toyosuna Station opened between Shin-Narashino and Kaihin-Makuhari. On 14 March 2024 the commuter rapid service was abolished. On 1 July 2026 JR East changed from branch offices to business headquarters. The Tokyo Business Headquarters manages the section near Tokyo Station, the Boso Business Headquarters manages the section near Soga, and the Keiyo-Sobu Business Headquarters manages the rest.
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Written by an AI from the line's history on Japanese Wikipedia, nothing else, and checked by a program for dates and numbers that are not in those facts. It can still be wrong. Adapted from Japanese Wikipedia, CC BY-SA 4.0; this text is shared under the same licence.