# Uchibō Line

The Uchibō Line (内房線, Uchibō-sen) is a railway line operated by the East Japan Railway Company (JR East) adjacent to Tokyo Bay, paralleling the western (i.e., inner) shore of the Bōsō Peninsula. It connects Soga Station in the city of Chiba to Awa-Kamogawa Station in the city of Kamogawa, passing through the municipalities of Chiba, Ichihara, Sodegaura, Kisarazu, Kimitsu, Futtsu, Kyonan, Tateyama, and Minamibōsō. The line is connected at both ends to the Sotobō Line. The name of the Uchibō Line in the Japanese language is formed from two kanji characters. The first, 内, means "inner" and the second, 房 is the first character of the Bōsō. The name of the line thus refers to its location along the inner part of the Bōsō Peninsula in relation to the Tokyo Metropolitan Area, as opposed to the Sotobō Line, "outer Bōsō" which is on the opposite side of the peninsula. South of Kimitsu is single track, and north of Kimitsu is double track.

## Station list
### Legend

* ● : All trains stop
* | : All trains pass

### Notes

* Local trains stop at every station.
* See Limited Express Sazanami article also.
| Line name | Station | Japanese | Distance (km) | to/from Keiyō Line | to/from Sōbu Line (Rapid) | Connecting lines | Location |
| Line name | Station | Japanese | Distance (km) | Rapid | Rapid | Connecting lines | Location |
| Sotobō Line | Chiba | 千葉 | From Chiba 0.0 | | ● | JO Sōbu Line (Rapid) (JO28) (some through services) JB Chūō-Sōbu Line (JB39) ■ Sōbu Main Line ■ Narita Line Chiba Urban Monorail Line 1, Line 2 KS Keisei Chiba Line (Keisei Chiba: KS59) | Chūō-ku, Chiba |
| Sotobō Line | Hon-Chiba | 本千葉 | 1.4 | | ● | | Chūō-ku, Chiba |
| Sotobō Line | Soga | 蘇我 | 3.8 | ● | ● | JE Keiyō Line (some through services) ■ Sotobō Line | Chūō-ku, Chiba |
| Uchibō Line | Soga | 蘇我 | From Soga 0.0 | ● | ● | JE Keiyō Line (some through services) ■ Sotobō Line | Chūō-ku, Chiba |
| Uchibō Line | Hamano | 浜野 | 3.4 | ● | ● | | Chūō-ku, Chiba |
| Uchibō Line | Yawatajuku | 八幡宿 | 5.6 | ● | ● | | Ichihara |
| Uchibō Line | Goi | 五井 | 9.3 | ● | ● | Kominato Railway Kominato Line | Ichihara |
| Uchibō Line | Anegasaki | 姉ケ崎 | 15.1 | ● | ● | | Ichihara |
| Uchibō Line | Nagaura | 長浦 | 20.5 | ● | ● | | Sodegaura |
| Uchibō Line | Sodegaura | 袖ケ浦 | 24.4 | ● | ● | | Sodegaura |
| Uchibō Line | Iwane | 巌根 | 27.5 | ● | | | | Kisarazu |
| Uchibō Line | Kisarazu | 木更津 | 31.3 | ● | ● | ■ Kururi Line | Kisarazu |
| Uchibō Line | Kimitsu | 君津 | 38.3 | ● | ● | | Kimitsu |
| Uchibō Line | Aohori | 青堀 | 42.0 | ● | | | Futtsu |
| Uchibō Line | Ōnuki | 大貫 | 46.6 | ● | | | Futtsu |
| Uchibō Line | Sanukimachi | 佐貫町 | 50.7 | ● | | | Futtsu |
| Uchibō Line | Kazusa-Minato | 上総湊 | 55.1 | ● | | | Futtsu |
| Uchibō Line | Takeoka | 竹岡 | 60.2 | | | | Futtsu |
| Uchibō Line | Hamakanaya | 浜金谷 | 64.0 | | | | Futtsu |
| Uchibō Line | Hota | 保田 | 67.5 | | | | Kyonan, Awa District |
| Uchibō Line | Awa-Katsuyama | 安房勝山 | 70.8 | | | | Kyonan, Awa District |
| Uchibō Line | Iwai | 岩井 | 73.7 | | | | Minami-Bōsō |
| Uchibō Line | Tomiura | 富浦 | 79.8 | | | | Minami-Bōsō |
| Uchibō Line | Nako-Funakata | 那古船形 | 82.1 | | | | Tateyama |
| Uchibō Line | Tateyama | 館山 | 85.9 | | | | Tateyama |
| Uchibō Line | Kokonoe | 九重 | 91.7 | | | | Tateyama |
| Uchibō Line | Chikura | 千倉 | 96.6 | | | | Minami-Bōsō |
| Uchibō Line | Chitose | 千歳 | 98.6 | | | | Minami-Bōsō |
| Uchibō Line | Minamihara | 南三原 | 102.2 | | | | Minami-Bōsō |
| Uchibō Line | Wadaura | 和田浦 | 106.8 | | | | Minami-Bōsō |
| Uchibō Line | Emi | 江見 | 111.4 | | | | Kamogawa |
| Uchibō Line | Futomi | 太海 | 116.0 | | | | Kamogawa |
| Uchibō Line | Awa-Kamogawa | 安房鴨川 | 119.4 | | | ■ Sotobō Line (some through services) | Kamogawa |
Notes:
* Special Rapid services were discontinued from 4 March 2017.
* Commuter Rapid services to/from Keiyo Line were discontinued from 16 March 2024.

## Operation

The Uchibō Line operates local service with trains generally originating and terminating at Chiba Station. Trains headed directly for Tokyo Station merge with the Sotobō Line between Soga and Chiba Stations, and with the Sōbu Main Line between Chiba and Tokyo, while express and commuter trains merge with the Keiyō Line from Soga station.

### Local trains

Daytime local service from Chiba to Kisarazu and Kimitsu (sometimes to Kazusa-Minato) is provided by around 2 round trips per hour. In addition, 1 round trip per hour runs from Kisarazu to Awa-Kamogawa (and to Kazusa-Ichinomiya through the Sotobō Line).

### Keiyō Line through service

Keiyō Line Local, Rapid, and Commuter Rapid trains operate through services on the Uchibō Line between Soga and Kimitsu. In the morning, there are three inbound Rapid and Commuter Rapid trains, and in the evening, there are five outbound Rapid and Commuter Rapid trains and two inbound Local trains. On weekends and holidays, Rapid trains replace the Commuter Rapid trains. One of the inbound morning trains originates from Kazusa-Minato.

### Yokosuka Line—Sōbu Line Rapid through service

Trains leaving north from Kimitsu connect directly to the Sōbu Line (Rapid), with some continuing onto the Yokosuka Line. Since the October 2004 timetable revision, all trains now stop at Nagaura and Sodegaura stations.

### Limited express trains

The limited express train Sazanami runs from Tokyo Station to Kimitsu (and Tateyama station during busy periods). The limited express View Sazanami formerly ran on the Uchibō Line as well, but it was merged with the Sazanami following the timetable revision on December 10, 2005. The limited express Shinjuku Sazanami runs from Shinjuku to Tateyama on weekends and during peak seasons.

## Rolling stock

Local service
* E131 series 2-car EMUs (since 13 March 2021)
* 209-2000/2100 series 4/6-car EMUs (since 1 October 2009)
Keiyō Line through service
* 209-500 series 10-car EMUs
* E233-5000 series 10-car EMUs
Yokosuka Line—Sōbu Line Rapid through service
* E235-1000 series 11+4-car EMUs with 2 green cars
Sazanami and Shinjuku Sazanami Limited Express
* 255 series EMUs with 1 green car
* E257-500 series EMUs

## History

The Uchibō line began operation in 1912, and was originally known as the Kisarazu Line (木更津線). It operated from Soga Station to Anegasaki Station in Ichihara. Several extensions were built over the next few years, and in 1919 it reached Awa-Hōjō (present day Tateyama). At this time it was renamed the Hōjō Line (北条線). By 1925 it had been extended to its present-day terminus, Awa-Kamogawa Station.
In 1929, the Hōjō Line was incorporated into the Bōsō Line. However, in 1933, the original section between Soga and Awa-Kamogawa Stations again became its own line, this time renamed the Bōsō West Line (房総西線), and in 1972 it received its current name.
The Soga - Kimitsu section was duplicated between 1964 and 1971, and the entire line was electrified between 1968 and 1971. Individual section dates as given in the Timeline section below.

### Timeline

* March 28, 1912 – Kisarazu Line (Soga to Anegasaki) begins operation
* August 21, 1912 – Extended from Anegasaki to Kisarazu
* January 15, 1915 – Extended from Kisarazu to Kazusa-Minato
* October 11, 1916 – Extended from Kazusa-Minato to Hamakanaya
* August 1, 1917 – Extended from Hamakanaya to Awa-Katsuyama
* August 10, 1918 – Extended from Awa-Katsuyama to Nako-Funakata
* May 24, 1919 – Extended from Nako-Funakata to Awa-Hōjō; renamed Hōjō Line
* June 1, 1921 – Extended from Awa-Hōjō to Minamihara
* December 20, 1922 – Extended from Minamihara to Emi
* July 25, 1924 – Extended from Emi to Futomi
* July 11, 1925 – Extended from Futomi to Awa-Kamogawa
* June 16, 1926 – Takeoka station opened
* May 20, 1927 – Chitose railyard opened
* August 15, 1929 – Bōsō line extended to Awa-Kamogawa; Hōjō Line incorporated into Bōsō Line
* August 1, 1930 – Chitose railyard is upgraded to a station
* April 1, 1933 – Bōsō line from Soga to Awa-Kamogawa (the run of the former Hōjō Line) is renamed Bōsō West Line
* November 20, 1941 – Iwane station opened
* March 1, 1946 – Awa-Hōjō station renamed Tateyama Station
* January 10, 1947 – Nagaura station opened
* April 10, 1956 – Shūsai station renamed Kimitsu Station
* July 1, 1964 – Double-track section built between Soga and Hamano
* September 20, 1964 – Double track extended from Hamano to Yawatajuku
* July 4, 1965 – Double track extended from Yawatajuku to Goi
* May 26, 1968 – Double track extended from Goi to Nagaura
* July 13, 1968 – Electric wires extended from Chiba station, past Sogo, extending to Kisarazu
* March 20, 1969 – Double track extended from Nagaura to Naraba
* July 10, 1969 – 135 C57-105 steam engines removed from service
* July 11, 1969 – Electric wires extended from Kisarazu to Chikura
* March 18, 1970 – Double track extended from Naraba to Kisarazu
* March 24, 1970 – Double track extended from Kisarazu to Kimitsu
* July 1, 1971 – Electric wires extended from Chikura to Awa-Kamogawa
* July 15, 1972 – Renamed Uchibō Line
* March 31, 1974 – Naraba station renamed Sodegaura
* November 15, 1982 – Freight service between Kisarazu and Awa-Kamogawa discontinued
* April 1, 1987 – Acquired by East Japan Railway Company following the division and privatization of JNR initiated by prime minister Yasuhiro Nakasone; Japan Freight Railway Company becomes a second class railway enterprise between Soga and Kisarazu
* November 1, 1996 – Japan Freight Railway Company second class enterprise between Soga and Kisarazu is discontinued
* February 4, 2001 – ATS-P usage implemented between Chiba and Iwane
* October 1, 2009 - 209-2000/2100 series EMUs are introduced on local services
* March 13, 2021 - E131 series EMUs are introduced on local services between Kisarazu and Awa-Kamogawa, replacing most 209-2000/2100 series trains in that section