Ibara Line

The corridor it follows had long been served by light railways. From 1913 the Ibasa Railway ran a narrow-gauge network in the area, beginning with its main line between Kasaoka and Ibara and later adding branch lines toward Yakage and Kannabe. The Japanese National Railways (JNR), meanwhile, operated buses between Kurashiki, Kiyone and Yakage and had long planned a proper rail line — the Ibara Line — to connect Sōja, Ibara and Kannabe as an extension of the Kibi Line corridor.

Construction of the JNR Ibara Line finally began with a groundbreaking ceremony on 14 May 1966, the route being built as a new national-railway line. As the state line advanced, the parallel light railways were wound up: the Ibasa Railway's Kannabe and Yakage branch lines closed in 1967 and its main line in 1971, and the abandoned trackbed was bought up by the Japan Railway Construction Public Corporation to be reused for the new line.

The project then stalled. In 1980 the enactment of the JNR Reconstruction Law — the legislation that sought to stem the national railway's mounting deficits by halting marginal construction — led to the JNR Ibara Line being cancelled while still unfinished, with substantial earthworks and viaducts already in place but no track or service.

The line was rescued by local government. In 1986, after the JNR project had been abandoned, the Ibara Railway was founded as a third-sector company led by Okayama and Hiroshima prefectures together with the surrounding municipalities, and from 1987 construction resumed, making use of the viaducts and formation that had already been completed under the JNR scheme.

Work was finished in the late 1990s. A rail-fastening ceremony marking completion of the track was held on 30 June 1998, and on 11 January 1999 the Ibara Line opened to traffic between Sōja, Kiyone and Kannabe — bringing into use, after more than thirty years, the route the state had first broken ground on in 1966. The short Sōja–Kiyone section, shared with the JR West Hakubi Line, is double-track and electrified at 1,500 V DC, while the remainder built by the Ibara Railway is single-track and non-electrified; all Ibara Railway services are operated by diesel railcars.

In the years since opening, the line has consolidated as a rural commuter and local railway. Through-running into Sōja Station was reduced in 2003, all trains went over to one-man operation in 2010, and the maximum line speed was lowered from 110 to 95 km/h in 2011. The railway carried its twenty-millionth cumulative passenger in May 2017. In July 2018 the line was knocked out by the heavy rains that struck western Japan: the whole line was suspended on 6 July, the Mitani–Kannabe section reopened on 10 July, and full service was restored on 3 September 2018.

• 191317 November: the Ibasa Railway opens its main line (Kasaoka–Ibara), the start of the light-railway network that earlier served the corridor.
• 196614 May: groundbreaking ceremony for the JNR Ibara Line; construction begins as a new national-railway line (planned Sōja–Ibara–Kannabe).
• 1967The Ibasa Railway's Kannabe Line and Yakage Line are abolished as the parallel JNR line advances.
• 1971The Ibasa Railway's main line is abolished; its abandoned trackbed is bought by the Japan Railway Construction Public Corporation for reuse.
• 1980The JNR Reconstruction Law takes effect; construction of the JNR Ibara Line is cancelled while still unfinished.
• 1986The third-sector Ibara Railway is established, led by Okayama and Hiroshima prefectures and the surrounding municipalities.
• 1987Construction resumes under the Ibara Railway, reusing the viaducts and formation already completed under the JNR scheme.
• 199830 June: a rail-fastening ceremony marks completion of the track.
• 199911 January: the Ibara Line opens between Sōja, Kiyone and Kannabe — the Sōja–Kiyone section (shared with the Hakubi Line) double-track and electrified, the rest single-track and non-electrified, worked by diesel railcars.
• 20031 October: through-services into Sōja Station are reduced.
• 201013 March: all trains go over to one-man operation, and a holiday timetable is introduced.
• 2011June: the maximum line speed is lowered from 110 km/h to 95 km/h.
• 201721 May: cumulative ridership since opening reaches 20 million passengers.
• 20186 July: the whole line is suspended in the July 2018 heavy rains; the Mitani–Kannabe section reopens on 10 July and full service is restored on 3 September.