Naniwasuji Line

The Naniwasuji Line (なにわ筋線, Naniwasuji-sen) is the tentative name for a planned underground heavy rail line, which will run north-south through Osaka City, primarily under the avenue Naniwa-suji. It has long been pursued by West Japan Railway Company (JR West) and Nankai Railway in order to connect the Yamatoji Line (Kansai Main Line) and Nankai Main Line with Shin-Osaka Station, greatly enhancing both companies' connections to Kansai Airport and Wakayama Prefecture. As of 2017, construction is expected to begin within the next few years and last until spring 2031. Hankyu Railway has also announced tentative plans to build a new underground line connecting the Naniwasuji Line to Juso and possibly a Shin-Osaka Station of its own.

Background

While both JR and Nankai operate trains to Wakayama (via the Hanwa Line and the Nankai Main Line, respectively) and to Kansai Airport (both via the Kansai Airport Line), neither route is ideal. For JR, trains must use the Osaka Loop Line past Tennoji Station, both creating and being affected by delays on that line, and bypassing JR Namba Station, the company's closest link to Osaka's commercial center. Additionally, express trains to Shin-Osaka and Kyoto must use the Umeda Freight Line, bypassing Osaka Station entirely. For Nankai, all trains go direct to its terminal in Namba, precluding links to points further north.

The issue surrounding Osaka Station for JR is set to be alleviated in spring 2019 with the opening of Phase II of the Osaka Higashi Line, which will terminate at a new Kita-Umeda Station adjacent to Osaka Station on a route replacing the above-ground Umeda Freight Line. Without constructing an entirely new line through central Osaka, however, the other problems remain.

Plans were drawn up in the mid-2000s to alleviate the problems for both companies through the construction of a new underground line, primarily under the north-south thoroughfare Naniwa-suji (hence the name), branching at its south end to connect both the Yamatoji Line (Kansai Main Line) terminal at JR Namba, and a Nankai line, with Shin-Osaka via a new underground route through what was then the Umeda Freight Terminal. The Umeda portion of this plan was eventually incorporated into Phase II of the Osaka Higashi Line, with provisions in place for eventual construction of the Naniwasuji Line itself. Early plans for Nankai called for moving the Shiomibashi Line (the northern end of the Kōya Line) underground and connecting to the Naniwasuji Line via Shiomibashi Station (thus upgrading and increasing traffic on an otherwise lightly traveled, local route), but the company ultimately rejected this routing in favor of one via a new underground station at Namba.

Current Plans

Current plans are to begin construction once the Osaka Higashi Line opens to Kita-Umeda, with completion anticipated in spring 2031. Total construction costs, including provisions for the line at Kita-Umeda, are projected to total some 330 billion yen.

Stations

Excluding the northern terminus at Kita-Umeda (opening in 2019 for the Osaka Higashi Line) and the existing JR Namba, three stations (all names tentative) are to be constructed: Nakanoshima (in the vicinity of the Keihan station), Nishi-Hommachi (likely near Chuo-Odori and Utsubo Park), and Nankai Shin-Namba (underground in the vicinity of Nankai Namba, potentially underneath the "Carnival Mall" approach to Namba Parks). The line will also pass through the vicinity of Fukushima (Osaka Loop Line, Hanshin Main Line), Shin-Fukushima (JR Tozai Line) and Nishiōhashi (Subway Nagahori Tsurumi-ryokuchi Line), although no stations are currently planned for these locations.