The Hakkoda Tunnel, completed in February 2005, is located between Tenmabayashi-mura and Aomori City in Aomori Prefecture, with a total length of 26,455m. It is the longest land-based double track tunnel in the world.
The railway of Tohoku Shinkansen between Hachinohe Station and Shin-Aomori Station (81.2km) is now under construction, with completion aimed for 2010. Along the length of the railway is the Hakkoda Range of 16 mountains. The Hakkoda Tunnel is located in the northern end of Hakkoda Mountain. It passes through the Hakkoda Range and links the village of Tenmabayashi-mura with Aomori City. The entire length of its 26,455m covers 1/3 of the Tohoku Shinkansen railway between Hachinohe and Shin-Aomori. When it opens, it will link Shichinohe Station (a tentative name) and Shin-Aomori Station.
Construction of the Tunnel started in August 1998 and digging began in June 1999. The entire project was divided into six sections. It was completed on February 27, 2005 – six and a half years later. It surpassed the Iwate-Ichinohe Tunnel (25.81km) of the same Tohoku Shinkansen railway to become the longest land-based tunnel in the world. However, about two months later, Lotschberg Base Tunnel (about 34.6km) in Switzerland finished construction on April 28, 2005, forcing Hakkoda to give uｐ its title of the longest land-based tunnel in the world.
The Lotschberg Base Tunnel began service on June 15, 2007, but only 1/3 of its south side is double-track, while the rest is single-track. Therefore, the Hakkoda Tunnel is still the longest land-based double track tunnel in the world.