Keisei Chihara Line

The line began life as a project of the Kominato Railway, a company based mainly in Ichihara, which applied for a licence in the late 1950s. The idea was to build a new branch diverging from Amaariki Station on the existing Kominato Railway Line and running directly to Hon-Chiba, so that commuters who were then travelling to central Chiba and Tokyo the long way round — via Goi on the national railway's Uchibō Line — could reach the city more quickly. New-town development was already under way along the Kominato line, and the company hoped to capture both the growing ridership and the fare revenue that the development would bring.

The licence for the Hon-Chiba–Amaariki line was granted in December 1957, but the Kominato Railway lacked the capital to build it, and the project lay dormant for years. In the 1970s the Housing and Urban Development Corporation planned a large new town straddling south-eastern Chiba and northern Ichihara directly along the licensed route, and the scheme was revived as an access railway for it. In December 1975 the licence was transferred to Chiba Kyūkō Dentetsu (the Chiba Express Electric Railway), a third-sector company backed by Keisei Electric Railway together with Chiba Prefecture and the cities of Chiba and Ichihara.

Under Chiba Kyūkō the plan was brought into line with Keisei's standards: standard 1,435 mm gauge and 1,500 V DC electrification, with the starting point shifted to Keisei Chiba Station (today's Chiba-Chūō Station) so that trains could run through onto the Keisei Chiba Line. The route was also altered. The original alignment had run straight from the Gakuenmae area via Tatsumidai and Kokubunjidai to Amaariki; the revised plan shifted it about 1.5 kilometres east to pass through the new Oyumino and Chihara-dai districts, which is why the line skirts the south-western edge of the new town rather than running through its centre. A route change for the section south of Gakuenmae was approved in March 1977, and construction began that year.

Chiba Kyūkō opened the first section, from Chiba-Chūō to Ōmoridai (4.2 km), on 1 April 1992 as the Chiba Kyūkō Line. On 1 April 1995 the line was extended a further 6.7 kilometres from Ōmoridai to Chiharadai, completing the present 10.9-kilometre route. The whole line was built as single track, but with land already secured for future doubling, and at the time of opening the company still expected to double the existing section — targeted for around 2000 — and to extend the line beyond Chiharadai toward Tatsumidai.

The collapse of Japan's asset-price bubble undermined those plans. Development of Oyumino and Chihara-dai slowed, the population along the line grew more slowly than forecast, and the high fares needed to recoup heavy land-acquisition costs, together with depreciation and interest burdens, left ridership well below projections. Chiba Kyūkō fell into insolvency and failed. In 1998 Keisei Electric Railway, its largest shareholder, took over operations and renamed the line the Chihara Line; the takeover took effect on 1 October 1998. Keisei also inherited the still-unbuilt licence for the Chiharadai–Amaariki section, though the extension and the doubling of the existing line were in effect frozen.

Keisei kept Chiba Kyūkō's fare structure, under which the Chihara Line is charged separately from the rest of the Keisei network and its fares are notably higher than those on neighbouring lines, a long-standing point of complaint among residents. Operations have since been modernised: the line's original Type 1 ATS was replaced by digital C-ATS in December 2016, and from 26 November 2022 some daytime four-car services began running as one-man operations. The extension toward Amaariki has not been abandoned — in 2020 it emerged that Keisei had extended the construction-permit deadline for the Chiharadai–Amaariki section by ten years to 14 October 2029, citing continued development potential along the planned route.

• 195727 December: the Kominato Railway obtains a local-railway licence for the Hon-Chiba–Amaariki line.
• 197520 December: the licence is transferred from the Kominato Railway to the third-sector Chiba Kyūkō Dentetsu (Chiba Express Electric Railway), backed by Keisei and local governments.
• 197730 March: the route change for the section south of Gakuenmae is approved; construction begins the same year (EN: August).
• 19921 April: Chiba Kyūkō opens the first section, Chiba-Chūō–Ōmoridai (4.2 km), as the Chiba Kyūkō Line.
• 19951 April: the line is extended from Ōmoridai to Chiharadai (6.7 km), completing the 10.9 km route.
• 19981 October: after Chiba Kyūkō becomes insolvent, Keisei Electric Railway takes over the line and renames it the Chihara Line, also inheriting the unbuilt Chiharadai–Amaariki licence.
• 201610 December: the line's original Type 1 ATS, in use since opening, is replaced with digital C-ATS.
• 202226 November: one-man operation begins on some daytime four-car services.
• 202914 October: deadline for the construction-permit application for the unbuilt Chiharadai–Amaariki extension (8.2 km); Keisei extended the earlier 2019 deadline by ten years in 2020.