GIFU -- Central Japan Railway Co. (JR Tokai) announced on Jan. 22 that a municipal road in Nakatsugawa, Gifu Prefecture, has sunk by more than 3 centimeters near the construction site of the Komamba tunnel for the Linear Chuo Shinkansen maglev train line.

The company attributed the problem to the excavation work loosening the soil above the tunnel.

At a Jan. 22 meeting of Gifu Prefecture's ground subcommittee under the environmental impact assessment review committee, JR Tokai explained that the municipal road is about 9 meters above the tunnel. Monitoring began in December 2024, when excavation work approached directly beneath the road. The company reported that the rate of subsidence has been slowing.

The municipal road remains open to traffic, and no significant sinkholes or collapses have been observed on nearby residential properties. Inside the tunnel, groundwater seepage of approximately 10 liters per minute has been recorded, though JR Tokai stated that this is unlikely to be connected to the subsidence.

To address the issue, JR Tokai plans to reinforce the ground by installing additional steel pipes and bolts from the tunnel's ceiling to its lower sections.

Separately, ground subsidence has also been reported near another Linear Chuo Shinkansen construction site in the Okute district of Mizunami, Gifu Prefecture. During a residents' meeting on Jan. 18, JR Tokai acknowledged that the subsidence in that area was also likely caused by tunnel excavation.

(Japanese original by Keisuke Ota, Gifu Bureau)