Sennichimae Line

The route originated in 1948, when it was separated from the earlier east–west plan for the Chūō Line (Line 4) and laid out as a trunk-grade line of its own, intended to run from the lower bank of the Kanzaki River to Hirano-ku. It was the third railway in Japan, after the Tōkaidō Shinkansen and the Nagoya Municipal Subway's Meijō Line, to adopt cab signalling, and from the outset it served as the Osaka municipal subway's testbed for automatic train operation (ATO).

The line opened in stages from 1969. Its first section, the 3.7 km between Nodahanshin and Sakuragawa, opened on 16 April 1969 as Line No. 5, equipped with centralised traffic control (CTC) and cab-signal CS-ATC and worked at first by two-car trains. The eastern Tanimachi 9-chōme–Imazato section (2.6 km) followed on 25 July 1969 and the Imazato–Shin-Fukae section (0.9 km) on 10 September 1969. The through name "Sennichimae Line" was adopted on 6 December 1969, and on 11 March 1970 the Sakuragawa–Tanimachi 9-chōme section (2.4 km) opened, joining the two halves into a continuous route as train formations were lengthened to four cars.

From its earliest years the line hosted an extended programme of automatic-operation trials. On-vehicle pattern-type ATO running tests began in October 1969 between Tanimachi 9-chōme and Shin-Fukae using 50 series cars, and revenue running with on-vehicle pattern ATO between Nodahanshin and Shin-Fukae started on 1 October 1970. From December 1971 a fully ground-based ATO system was tested on the westbound Imazato–Shin-Fukae track, in which a wayside installation sent power, coast and braking commands to each individual train; according to Japanese sources this was the first fully ground-based train-control system in the country. The trials ran until July 1973, the ATO revenue operation ended on 31 July 1974, and the Osaka Municipal Transportation Bureau's automatic-operation project was wound up on 6 August 1974.

The line was completed to its full length on 2 December 1981, when the 3.0 km section from Shin-Fukae to Minami-Tatsumi opened. Because platform demand is comfortably met by four-car trains, services have continued to run as four-car formations even though every platform was built long enough for eight cars, with the unused portions partly fenced off.

Rolling stock evolved over the following decades. The 100 series cars were withdrawn in March 1989, the purpose-built 25 series — the line's first new-build trains and its first air-conditioned cars — entered service from 30 June 1991, 30 series cars were drafted in from August 1991, and by July 1995 the fleet had been standardised entirely on the 25 series. All-night running on New Year's Eve began on 31 December 1994.

The 2010s brought automation back to the line, this time permanently. From 15 February 2014 ATO came into use in preparation for one-man (driver-only) operation, and platform screen doors were fitted across the line during the year, the installation being completed at Nodahanshin on 13 December 2014. Driver-only operation began on 13 January 2015, after a preparatory period during which a conductor still rode while the driver handled all the door and equipment operation. Operating crews were moved from the Awaza crew base to a new Imazato crew base from 22 March 2015.

On 1 April 2018 the operator changed: with the corporatisation of the Osaka municipal subway, the Sennichimae Line, like the rest of the network, passed from the Osaka Municipal Transportation Bureau to the newly created Osaka Metro Co., Ltd. (formally Osaka City Rapid Electric Tramway, 大阪市高速電気軌道). Today the Sennichimae Line remains a compact but heavily used cross-town subway, worked by automatically driven 25 series trains behind platform screen doors and connecting with every other Osaka Metro subway line except the New Tram Nankō Port Town Line.

• 1948The route is separated from the earlier east–west plan for the Chūō Line (Line 4) and planned as a trunk-grade line of its own, from the lower bank of the Kanzaki River to Hirano-ku.
• 196916 April: the first section, Nodahanshin–Sakuragawa (3.7 km), opens as Line No. 5 with CTC and cab-signal CS-ATC; two-car operation begins.
• 196925 July: the Tanimachi 9-chōme–Imazato section (2.6 km) opens. 10 September: the Imazato–Shin-Fukae section (0.9 km) opens.
• 1969October: on-vehicle pattern-type ATO running tests begin between Tanimachi 9-chōme and Shin-Fukae using 50 series cars. 6 December: the through name 'Sennichimae Line' is adopted.
• 197011 March: the Sakuragawa–Tanimachi 9-chōme section (2.4 km) opens, joining the two halves; trains are lengthened to four cars. 1 October: revenue running with on-vehicle pattern ATO begins between Nodahanshin and Shin-Fukae.
• 1971December: a fully ground-based ATO system begins practical trials on the westbound Imazato–Shin-Fukae track — per Japanese sources, the first fully ground-based train-control system in Japan — running until July 1973.
• 197431 July: ATO revenue operation ends. 6 August: the Osaka Municipal Transportation Bureau's automatic-operation project is discontinued.
• 19812 December: the Shin-Fukae–Minami-Tatsumi section (3.0 km) opens, completing the line to its full 12.6 km length.
• 1989March: the 100 series cars are withdrawn from the line.
• 199130 June: the purpose-built 25 series — the line's first new-build and first air-conditioned cars — enters service; 30 series cars are also drafted in from August.
• 199431 December: all-night running on New Year's Eve begins.
• 1995July: the fleet is standardised entirely on the 25 series.
• 201415 February: ATO comes into use in preparation for one-man operation. 13 December: platform screen doors are completed at Nodahanshin, finishing installation across all stations on the line.
• 201513 January: driver-only (one-man) operation begins. 22 March: operating crews move from the Awaza crew base to the new Imazato crew base.
• 20181 April: the Osaka municipal subway is corporatised; the Sennichimae Line passes from the Osaka Municipal Transportation Bureau to the new Osaka Metro Co., Ltd. (Osaka City Rapid Electric Tramway).