Sotetsu/Tokyu Shin-Yokohama Line

Two underground railway lines opened simultaneously on 18 March 2023 — the Tokyu Shin-Yokohama Line (Hiyoshi–Shin-Yokohama, 5.8 km) and the Sotetsu Shin-Yokohama Line (Nishiya–Shin-Yokohama, 6.3 km) — completing a through-running network spanning seven operators and fourteen lines across some 250 kilometres.

A Thirty-Eight-Year Plan Completed Underground

On 18 March 2023, two underground railway lines opened simultaneously in Yokohama. Tokyu Corporation’s Tokyu Shin-Yokohama Line runs from Hiyoshi to Shin-Yokohama, covering 5.8 kilometres across three stations. Sagami Railway’s Sotetsu Shin-Yokohama Line connects Nishiya to Shin-Yokohama across 6.3 kilometres and three stations. With Shin-Yokohama as the junction point, passengers from the Sotetsu network in western Yokohama can now reach Shibuya, Meguro, Otemachi, and stations as far as Saitama without a single transfer.

The route traces back to a 1985 government transport-policy council recommendation that first identified “the Kanagawa East Corridor Line” as a future infrastructure priority. A 2000 follow-up council recommendation refined the current alignment. Construction approval came in 2012, and tunnelling proceeded entirely underground. From the first written proposal to opening day spanned approximately 38 years.

Seven Operators, One Through-Running Network

The infrastructure was built and is owned by the Japan Railway Construction, Transport and Technology Agency (JRTT), which leases track access to Tokyu and Sotetsu under an upper-lower separation arrangement authorised by the 2004 Urban Railway Convenience Enhancement Act. Operators pay track-access fees, funding the construction cost over time.

The combined opening created a through-running network spanning seven operators and fourteen lines, covering approximately 250 kilometres. Via the Tokyu Meguro Line, Sotetsu trains reach the Toei Mita Line, Tokyo Metro Namboku Line, and Saitama Rapid Railway. Via the Tokyu Toyoko Line, services extend through the Tokyo Metro Fukutoshin Line to the Tobu Tojo and Seibu lines. For residents of western Yokohama, journeys that once required two or three transfers are now a single seat.

Summary

The Tokyu Shin-Yokohama Line (5.8 km, 3 stations) and the Sotetsu Shin-Yokohama Line (6.3 km, 3 stations) opened together on 18 March 2023, with Shin-Yokohama station as their shared junction. Together they completed a through-running network linking seven operators and fourteen lines across some 250 kilometres of track. Standing on the Shin-Yokohama platform and watching Sotetsu trains bound for Ebina and Tobu trains bound for Wakoshi share the same berth is the clearest measure of what thirty-eight years of planning produced underground.

Related: Takanawa Gateway / Shibuya Station Redevelopment

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