Uchiko Line

The corridor traces its origins to a railway planned in 1910 by the Saiyō Electric Tramway, whose route was to run from Gunchū on the Iyo Railway over the Inuyose Pass and through Nakayama, Uchiko and Ōzu to Yawatahama. The promoter became the Ehime Railway in 1912, and in 1916 the plan was changed to avoid the difficult Inuyose Pass in favour of an easier alignment along the Iyo-nada coast. The coastal line from Nagahama-machi (today's Iyo-Nagahama) to Ōzu (today's Iyo-Ōzu) opened in 1918, and the route into the Uchiyama district was built as a branch.

On 1 May 1920 the Ehime Railway opened that branch, from Wakamiya Junction — a junction between Gorō and Ōzu, at the site of the present Iyo-Wakamiya Signal Station — to Uchiko. It was a 762 mm light railway. The Ehime Railway was nationalised on 1 October 1933, and both its lines were grouped together under the name Ehime Line.

A decisive reorganisation came on 6 October 1935. The Ehime Line was regauged to the 1,067 mm national standard, and on the same day the Iyo-Nagahama–Iyo-Ōzu section was incorporated into the Yosan Main Line, which had reached Iyo-Nagahama from Matsuyama. The remaining branch, now diverging at Gorō, gained its own identity as the Uchiko Line. The Yosan Main Line was then extended onwards from the junction at Gorō towards Uwajima in stages between 19 September 1936 and 20 June 1945. From 1 November 1958 all of the line's trains were diesel railcars, ending steam operation.

For decades the Uchiko Line was a quiet dead-end branch, and by the time the major restructuring of the national railways was being planned its traffic had fallen below 500 passengers per day — a level that would have qualified it as a first-round 'specified local line' for conversion or closure under the 1980 reconstruction law. It was saved not for its own sake but because of the Uchiyama Line, a planned shortcut for the Yosan Main Line whose groundbreaking had been held on 27 November 1966; folding the Uchiko Line into that through route was projected to lift traffic dramatically, and the segment was kept and completed. Freight operations on the line ceased on 1 December 1971.

The line was rebuilt to carry the new through traffic. On 25 November 1985 it was closed and replaced by substitute buses so that heavier rails could be laid, the roadbed strengthened and curves eased. On 3 March 1986 the upgraded line reopened as part of the shortcut route between Matsuyama and Uwajima: new Yosan Line sections from Mukaibara to Uchiko and from Niiya towards Iyo-Ōzu opened the same day, the old Gorō–Niiya section was abandoned, the stations at Isozaki and Uchiko were relocated, a passing loop was added at Niiya, and the whole route was placed under centralised traffic control. What had been a backwater branch became a line over which limited expresses ran.

At the privatisation of the Japanese National Railways on 1 April 1987 the Uchiko Line passed to JR Shikoku, with Japan Freight Railway holding running rights as a Type-2 operator; JR Freight withdrew from the line on 1 April 2006. Today the Uchiko Line is operated as one with the Yosan Line, carrying the 'Uwakai' limited expresses between Matsuyama and Uwajima as well as local trains, all of which run through onto the Yosan Line towards Iyo-shi and Iyo-Ōzu. In July 2020 heavy rain caused a slope to collapse between Isozaki and Kitayama, suspending the Uchiko–Iyo-Ōzu section from 4 July until services resumed on 20 July.

• 19201 May: the Ehime Railway opens the Wakamiya Junction–Uchiko branch (the junction being between Gorō and Ōzu, at the site of today's Iyo-Wakamiya Signal Station) as a 762 mm light railway.
• 19331 October: the Ehime Railway is nationalised; its lines are grouped together and named the Ehime Line.
• 19356 October: the line is regauged to 1,067 mm; the Iyo-Nagahama–Iyo-Ōzu section is incorporated into the Yosan Main Line, and the branch diverging at Gorō becomes the Uchiko Line.
• 193619 September: the Yosan Main Line begins to be extended from the junction at Gorō towards Uwajima, a process completed in stages by 20 June 1945.
• 19581 November: all trains on the line are replaced by diesel railcars, ending steam operation.
• 196627 November: the groundbreaking ceremony is held for the Uchiyama Line, the planned Yosan Main Line shortcut into which the Uchiko Line would later be folded.
• 19711 December: freight operations on the line cease.
• 198525 November: the line closes for reconstruction — heavier rails, a strengthened roadbed and eased curves — with passenger service replaced by substitute buses.
• 19863 March: the rebuilt line reopens as part of the Matsuyama–Uwajima shortcut; new Yosan Line sections from Mukaibara to Uchiko and from Niiya towards Iyo-Ōzu open, the old Gorō–Niiya section is abandoned, Isozaki and Uchiko stations are relocated, a passing loop is added at Niiya, and the route is placed under centralised traffic control (CTC).
• 19871 April: with the privatisation of Japanese National Railways the Uchiko Line passes to JR Shikoku, while Japan Freight Railway holds running rights as a Type-2 operator.
• 20061 April: JR Freight ends its Type-2 freight operations on the line.
• 20204 July: heavy rain causes a slope to collapse between Isozaki and Kitayama, suspending the Uchiko–Iyo-Ōzu section; service resumes on 20 July.