| Sotobō Line | |
| Color: | FF4500 |
| Stations: | 27 |
| Open: | 1896 |
| Linelength: | 93.3km (58miles) |
| Speed: | 110abbr=onNaNabbr=on |
The is a railway line in Japan operated by the East Japan Railway Company (JR East) adjacent to the Pacific Ocean, on the eastern (i.e., outer) side of the Bōsō Peninsula. It connects Chiba Station in Chiba to Awa-Kamogawa Station in Kamogawa, passing through Ōamishirasato, Mobara, Chōsei, Ichinomiya, Isumi, Onjuku, and Katsuura. The line is connected to the Uchibō Line at both ends. South of Kazusa-Ichinomiya is single track, and north of Kazusa-Ichinomiya is double track.
In addition to local services, limited express and Rapid services run on this line.
– (Keiyō Line) – –
(some operate as all-stations "Local" services between and Awa-Kamogawa
| Station | Japanese | Distance (km) | to/fromKeiyō Line | to/fromSōbu Line (Rapid) and Yokosuka Line | Transfers | Location (in Chiba) | ||
|---|---|---|---|---|---|---|---|---|
| Keiyō Line Rapid | Limited express Wakashio | Sōbu Line Rapid | Limited express Shinjuku Wakashio (Weekends only) | |||||
| 千葉 | 0.0 | ● | ● | Sōbu Line (Rapid) (JO28) (some through services) Chūō-Sōbu Line (JB39)
Chiba Urban Monorail Line 1, Line 2 Keisei Chiba Line (: KS59) | Chūō-ku, Chiba | |||
| 本千葉 | 1.4 | ● | || |-||蘇我| align="right" |3.8| style="background-color:MediumSeaGreen;" align="center" |●| align="center" |●| style="background-color:Lavender;" align="center" |●| align="center" |●| Keiyō Line (some through services) Uchibō Line|-|-||鎌取| align="right" |8.8| style="background-color:MediumSeaGreen;" align="center" |●| align="center" ||| style="background-color:Lavender;" align="center" |●|align="center"||| | rowspan="3" |Midori-ku, Chiba|-||誉田| align="right" |12.6| style="background-color:MediumSeaGreen;" align="center" |●| align="center" ||| style="background-color:Lavender;" align="center" |●|align="center"||| |-||土気| align="right" |18.1| style="background-color:MediumSeaGreen;" align="center" |●| align="center" |(●)| style="background-color:Lavender;" align="center" |●|align="center"||| |-||大網| align="right" |22.9| style="background-color:MediumSeaGreen;" align="center" |●| align="center" |●| style="background-color:Lavender;" align="center" |●| align="center" |●| Togane Line| rowspan="2" |Ōamishirasato|-||永田| align="right" |25.3| style="background-color:MediumSeaGreen;" align="center" |(●)| align="center" ||| style="background-color:Lavender;" align="center" |||align="center"|| | |||||
| 本納 | 27.7 | (●) | || style="background-color:Lavender;" align="center" |||align="center"|| | Mobara | ||||
| 新茂原 | 31.4 | (●) | || style="background-color:Lavender;" align="center" |||align="center"|| | |||||
| 茂原 | 34.3 | ● | ● | ● | ● | |||
| 八積 | 38.9 | (●) | || style="background-color:Lavender;" align="center" |||align="center"|| | Chōsei | ||||
| 上総一ノ宮 | 43.0 | ● | ● | ● | ● | Ichinomiya | ||
| 東浪見 | 46.2 | ● | || rowspan="14" ||align="center"||| |-||太東| align="right" |49.3| style="background-color:MediumSeaGreen;" align="center" |●| align="center" |||align="center"|| | Isumi | ||||
| 長者町 | 52.1 | ● | ||align="center"|| | |||||
| 三門 | 53.7 | ● | ||align="center"|| | |||||
| 大原 | 57.2 | ● | ● | ● | Isumi Line | |||
| 浪花 | 60.5 | ● | ||align="center"|| | |||||
| 御宿 | 65.4 | ● | ● | ● | Onjuku | |||
| 勝浦 | 70.9 | ● | ● | ● | Katsuura | |||
| 鵜原 | 74.5 | ||align="center"|| | ||||||
| 上総興津 | 77.2 | (●) | ● | |||||
| 行川アイランド | 80.5 | ||align="center"|| | ||||||
| 安房小湊 | 84.3 | ● | ● | Kamogawa | ||||
| 安房天津 | 87.7 | ||align="center"|| | ||||||
| 安房鴨川 | 93.3 | ● | ● | Uchibō Line (some through services) | ||||
Local service
Keiyō Line through service
Between and :
Sōbu Line (Rapid) through service
Between and :
Wakashio Limited Express
The Boso Railway opened the Chiba to Oami section in 1896, extending the line to Kazusa-Ichinomiya the following year and to Ohara in 1899. The company was nationalised in 1907. The extension to Katsuura opened in 1913, to Kazusa-Okitsu in 1927, and Awa-Kamogawa in 1929.
A new tunnel and associated deviation was opened at Toke in 1954 to improve the loading gauge of the line. The Chiba to Soga section was double-tracked between 1960 and 1963, extended to Nagata between 1972 and 1974, with CTC signalling being commissioned between Soga and Awa-Kamogawa in 1974. The line to Kazusa-Ichinomiya was double-tracked between 1980 and 1986, with the Onjuku to Katsuura section double-tracked in 1995, and the Torami to Chojamachi section the following year. The entire line was electrified in 1968, and freight services ceased between 1982 and 1987.
On 8 May 2020, at 3:55 pm, the front carriage of a local service derailed between Awa-Kamogawa and Awa-Amatsu stations. Around 20 passengers and crew were on board the train (a 209 Series) when it derailed. One person was taken to a hospital.[3]