General News

Tunnel Collapses at Hokkaido Shinkansen Extension Construction Site

Courtesy of the Japan Railway Construction, Transport and Technology Agency
The Sasson Tunnel construction site in Otaru, Hokkaido, is filled with soil and debris.

The Yomiuri Shimbun

12:10 JST, April 8, 2026

At an excavation site of a Hokkaido Shinkansen tunnel in Otaru, Hokkaido, a section of the ceiling has collapsed, causing soil and debris to pour in.

Workers found the collapse of in the Sasson Tunnel located about 200 meters underground in a forested areal of Otaru, Hokkaido, at about 7 p.m. on Monday.

There were no injuries to workers or damage to heavy machinery. The Japan Railway Construction, Transport and Technology Agency, which is overseeing the project, has suspended excavation work and is investigating the cause.

At the construction site, workers were removing excavated soil from the tunnel. There is a possibility that the ground near the site has subsided, so authorities plan to conduct an aerial survey using drones. There is currently no timeline for resuming construction.

Construction is underway to extend the Hokkaido Shinkansen from Shin-Hakodate-Hokuto in Hokuto, Hokkaido, to Sapporo. The Sasson Tunnel is part of the extension.