HOKKAIDO, Mar 30, 2026 (News On Japan) - The Hokkaido Shinkansen marked its 10th anniversary on March 26, as a town in southern Hokkaido known for its deep ties to tunnel construction put forward a bold proposal to build a second undersea tunnel to help achieve faster travel between Sapporo and Tokyo.
The Hokkaido Shinkansen’s H5 series trains currently run through the undersea Seikan Tunnel, where a separate track is used by freight trains. The coexistence of passenger and freight services within the same tunnel has become a key bottleneck.
Fukushima Town in Hokkaido, which served as a major base for the Seikan Tunnel’s construction from the 1960s through the 1980s, is promoting the idea of a “Second Seikan Tunnel.” The project reflects the town’s historical connection to the original tunnel, which once brought significant economic activity to the area.
Mayor Kiyoharu Narumi of Fukushima Town said, “Our town today exists because of the prosperity brought by the tunnel construction. Those who experienced that era remember how vibrant it was.”
The proposal is being highlighted alongside anniversary events running through March 29, but the idea of constructing a second tunnel raises questions due to its enormous cost. Still, local officials argue it is essential for the future of the Shinkansen network.
Narumi said that with the planned extension of the line to Sapporo, greater speed will be required. “To fully realize the appeal of the Shinkansen, another tunnel is necessary,” he said.
The Seikan Tunnel is currently the only section in Japan where Shinkansen and freight trains operate on the same tracks in opposite directions. To prevent cargo from being destabilized by the pressure of passing trains, Shinkansen speeds are reduced from their maximum of 320 kilometers per hour to around 160 kilometers per hour within the tunnel.
Separating freight and passenger traffic into different tunnels would allow Shinkansen trains to operate at higher speeds, bringing the goal of connecting Tokyo and Sapporo in four and a half hours closer to reality.
Three possible plans have been outlined for the second tunnel. The first proposes constructing a dedicated freight tunnel, allowing the existing tunnel to be used exclusively by Shinkansen trains at full speed. The second envisions a vertically divided tunnel, with automobiles traveling on the upper level and freight trains below. A third option suggests building a tunnel exclusively for road vehicles.
However, estimates place the project cost between 390 billion yen and 720 billion yen, far beyond what Fukushima Town could finance on its own.
Narumi emphasized that the initiative should be treated as a national project, saying, “It will take time, but we are raising our voice.”
Fukushima Town plans to lobby national lawmakers and other stakeholders in an effort to advance the proposal and move closer to realizing the long-held vision of a second Seikan Tunnel.
Source: HBCニュース 北海道放送
