Proposals put forward in the 1970s for a second route to Sapporo via Muroran and an extension of the line to Asahikawa have been shelved indefinitely.
At the time of writing, the fastest journey between Tokyo and Shin-Hakodate-Hokuto takes just over four hours.
By 2018, the rail authorities should have one shinkansen service each day travelling at 260 km/h through the tunnel. That can only happen if they can ensure no freight trains are moving on the dual-gauge section in the opposite direction.
Various arrangements that might allow faster speeds are, however, under investigation.
One possibility is an automatic system that would slow shinkansen services down to 200 km/h as they pass narrow-gauge trains. Another involves piggybacking freight trains onto reinforced standard-gauge trains built to withstand the shock wave of a full-speed oncoming shinkansen.
On Hokkaido, the dual line section splits at Kikonai, with the Kaikyō Line taking freight train services into Hakodate, while shinkansen services continue to Shin-Hakodate-Hokuto. From there a relay service (Hakodate Liner) transfers passengers into Hakodate via Goryōkaku. Local services on the Hakodate Main Line stop at intermediate stations on the way into Goryōkaku.
Alternatively, passengers disembarking from the shinkansen at Kikonai can make their way into Hakodate on the former narrow gauge Esashi Line, rebadged as the Isaribi Line when ownership was transferred from JR Hokkaido to a new third-sector railway company (South Hokkaido Railway Company).
Stations:
On Honshū: Shin-Aomori; Okutsugaru-Imabetsu
On Hokkaidō: Kikonai; Shin-Hakodate-Hokuto
Under construction: Shin-Yakumo; Oshamambe; Kutchan; Shin-Otaru; Shin-Sapporo