JR Tōzai Line

Unusually for a JR line, the JR Tōzai Line is operated under a split arrangement: the third-sector company Kansai Rapid Railway owns and maintains the track and other railway facilities as a Category-3 operator, while JR West runs the passenger trains as a Category-2 operator. The route was conceived as the Katafuku Connecting Line (片福連絡線), an underground link between the Katamachi Line, which served Osaka's eastern suburbs, and the Fukuchiyama Line, which served its north-western suburbs — its provisional name combining the "Kata" of Katamachi with the "fuku" of Fukuchiyama. Because Osaka's municipal government had long kept tight control over transport within the city and most intercity lines terminated outside the centre, such a through route promised commuters a single-seat ride across the heart of the city. In 1971 the project was identified in Urban Transport Council Report No. 13 as a line to be built urgently, but no work began.

In 1981 the scheme was authorised by the Ministry of Transport — framed as an additional track pair between Kyōbashi and Amagasaki over the Osaka Loop Line and Tōkaidō Main Line — but Japanese National Railways' financial troubles meant construction was again deferred. When JNR was divided and privatised in 1987, the licence for the Katafuku Connecting Line passed to JR West. As the new company could not fund the line on its own, the third-sector Kansai Rapid Railway was established in 1988 to build and own the railway facilities, leasing them to JR West for train operation. In 1989 the project was re-cast as a wide-area trunk line driving east-to-west through the city centre — linking the Katamachi and Fukuchiyama lines by mutual through-running and helping to relieve congestion on the Osaka Loop Line — and construction finally began that year.

Construction proved demanding: the line burrows beneath the existing subway network, underground shopping arcades and the Yodo River, giving it some of the steepest gradients in the JR West network, and its Kitashinchi Station, at 23.95 metres below sea level, is the deepest station the company operates. The line was the first to cross the Yodo River by an underwater tunnel, every earlier railway having bridged it. Originally due to open in the spring of 1995, the line was set back about two years by a water-inflow accident near Ebie. The formal name "JR Tōzai Line" was decided in May 1996, and after a rail-fastening ceremony that September the line opened between Kyōbashi and Amagasaki on 8 March 1997; on the same day the Katamachi Line's short Kyōbashi–Katamachi section was superseded by the new Kyōbashi–Ōsakajō-kitazume stretch and abolished, and the J-Through stored-fare card was introduced. Every station opened under a name different from its construction-era provisional title.

From opening, the JR Tōzai Line functioned as the central link in a much longer cross-city service rather than as a self-contained railway. Every train runs through at Kyōbashi onto the Gakkentoshi Line, and most westbound trains continue beyond Amagasaki onto the JR Takarazuka Line towards Takarazuka and Shin-Sanda or onto the JR Kobe Line towards Nishi-Akashi, so that the Gakkentoshi and JR Tōzai lines operate almost as a single system. Within the JR Tōzai Line itself every train stops at all stations, services being local, rapid and regional-rapid trains. From 2008 a Direct Rapid service also linked Nara with Amagasaki by way of the newly opened Osaka Higashi Line and the Gakkentoshi and JR Tōzai lines.

In its later years the line saw a series of incremental upgrades and changes. A women-only car was introduced in December 2002. From December 2010 the line's management passed from JR West's Osaka Branch to its Kinki Regional Headquarters, and in March 2011 a dedicated traffic-control system covering the JR Takarazuka, JR Tōzai and Gakkentoshi lines was brought into use. Also in March 2011, Kitashinchi Station became the first station on a JR West conventional line to be fitted with platform-edge doors, followed by Osaka-Temmangu in March 2012; the women-only car was extended to all-day, every-day operation in April 2011. Mobile-phone coverage reached the underground Kyōbashi–Amagasaki section in 2015, and station numbers were introduced in March 2018. The Direct Rapid service ended in March 2019 when the Osaka Higashi Line was opened along its full length.

• 1971The Katafuku Connecting Line (linking the Katamachi and Fukuchiyama lines) is identified in Urban Transport Council Report No. 13 as a line to be built urgently, but no construction begins.
• 1981The project is authorised by the Ministry of Transport as a track addition between Kyōbashi and Amagasaki, but is deferred owing to JNR's financial difficulties.
• 198825 May: Kansai Rapid Railway is established as the third-sector company to build and own the line's facilities. 28 October: it obtains the Category-2 railway business licence for the Katafuku Connecting Line.
• 198911 November: construction of the line begins.
• 199616 May: the formal name 'JR Tōzai Line' is decided. 25 September: a rail-fastening ceremony is held.
• 19978 March: the Kyōbashi–Amagasaki line opens. The Katamachi Line's Kyōbashi–Katamachi section is replaced by Kyōbashi–Ōsakajō-kitazume and abolished, and the J-Through card is introduced.
• 20022 December: a women-only car is introduced on the line.
• 200815 March: a Direct Rapid service begins between Nara and Amagasaki via the newly opened Osaka Higashi Line, the Katamachi (Gakkentoshi) Line and the JR Tōzai Line.
• 20101 December: management of the line is transferred from JR West's Osaka Branch to its Kinki Regional Headquarters in an organisational change.
• 20118 March: the JR Takarazuka/JR Tōzai/Gakkentoshi line traffic-control system is introduced. 27 March: Kitashinchi becomes the first station on a JR West conventional line to use platform-edge doors. 18 April: the women-only car is set to operate every day, all day.
• 201228 March: platform-edge doors enter use at Osaka-Temmangu Station.
• 201531 July: mobile-phone service begins in the underground Kyōbashi–Amagasaki section.
• 201817 March: station numbers are introduced at the line's stations.
• 201915 March: the Direct Rapid through-service ends, ahead of the Osaka Higashi Line's full opening the next day.