A high-speed race against shock waves and rising costs

Society · Published 9 October 2026 Swipe more like this →

In short: The Hokkaido Shinkansen connects Honshu to Hokkaido via the Seikan Tunnel, but it faces a unique engineering hurdle. To avoid destabilizing freight trains, high-speed services must often slow down. Now, a massive extension to Sapporo faces a different kind of threat: a plummeting cost-benefit ratio.

The 148.8-kilometre Hokkaido Shinkansen line, which opened its initial section between Shin-Aomori and Shin-Hakodate-Hokuto on 26 March 2016, operates at a maximum speed of 260 km/h. However, speed is not always constant. In the 82-kilometre dual-gauge section approaching and through the Seikan Tunnel, trains must manage the physical impact of passing other vehicles. Because approximately 50 freight trains use this section daily, the speed limit was initially set at 140 km/h to prevent shock waves from a Shinkansen train from destabilizing narrow-gauge freight trains. While this was increased to 160 km/h in March 2019, and can reach 260 km/h during major holiday periods, the restriction remains a factor in travel times.

Engineering solutions are being explored to reclaim lost time. One proposal involves a 'train on train' system, where standard-gauge Shinkansen would carry specially designed narrow-gauge vehicles capable of withstanding these shock waves, potentially reducing travel times by 12 minutes. Beyond physics, the line faces significant environmental and economic challenges. Winter weather can cause snow to accumulate in train bogies, with estimates predicting up to 3 cm of snow accumulation upon arrival at a station. This harsh climate contributes to low occupancy rates, which have dropped to 19% during January and February.

The future of the line hinges on the extension to Sapporo. Originally scheduled for fiscal year 2030, the opening has been pushed back to the end of FY2038. The delay follows reports that the extension would be 'extremely difficult' to complete on the original timeline. Moreover, the project's financial feasibility is being questioned; the Ministry of Finance calculated a 0.6 cost-benefit ratio in April 2026, which fails to meet the 1.0 minimum for new Shinkansen lines and labels the venture as something that 'should be discontinued in principle'.

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