High-speed trains using the Hokkaido Shinkansen are currently limited to 140km/h in the 53.9km Seikan Tunnel between the islands of Honshu and Hokkaido due the risk of pressure waves causing damage to passing freight trains.

Raising the maximum speed for passenger trains to 160km/h would reduce the fastest journey time for Tokyo - Shin Hakodate Hokuto Hayabusa express services from 4h 2min to 3h 59min.

JR Hokkaido plans to carry out tests in the 2018 financial year to establish whether its H5 Shinkansen trains can safely operate at higher speeds in the tunnel. If these tests are successful, 160km/h operation could be introduced in Spring 2019.