Key Points

IRCON, the executing agency for the project, stated that the landslide took place on a hill slope approximately 30 metres away from the portal of the T7 Adit Tunnel. The slide was limited to the left side and occurred in a private area outside the railway land's right-of-way (ROW).

"The main tunnel and the Adit Tunnel are safe and unaffected by the landslide, and there is no possibility of any damage to the Tunnel," IRCON said in a press statement.

The hill slope slide was triggered beyond the railway-protected hill slope, originating from within the forest area, due to non-stop rains in the hills since July 2025. Due to non-stop rains, seepage in the pre-existing hill cracks in the Forest area beyond the ROW leading to hill slope slide starting from the Forest land and seepage of the rain water in the hill slope caused movement of hill slope and slide of the boulders/debris from Forest area in to the Railway tunnel slope. It damaged the protected hill surface on the Left side of the Tunnel adit portal.

IRCON had taken adequate precautions in advance to move the machinery and manpower away from the hill slope. There are no casualties or injuries to workers or the general public, and no loss of machinery or railway assets during the incident. There is no damage to the adjacent civilian habitation near the Tunnel location.

The hills slope above the Adit portal, and on the Right side of the portal is stable as well. The Main tunnel portals are stable. The landslide occurred approximately 30 m away from the adit tunnel portal, and the tunnel itself remains unaffected, posing no danger. The adit tunnel, as well as the main tunnel, is safe and secure, and there is no possibility of any damage to the tunnel. However, in view of the continuous heavy rainfall, continuous monitoring and precautionary measures are being taken.

It is also worth noting that due to continuous rainfall in the hills from Sivok to Rangpo, NH-10 has also been damaged at several locations, affecting the movement of road traffic from Sivok to Rangpo and thereby affecting the Project works as well.

Work on debris removal and site protection has commenced. IRCON will assess the hill slope conditions after clearance of the debris for restoration of the hill slope, and the design of the hill slope stabilisation will be done through the intervention of geo-technical experts of M/s. Amberg for long-term stability and safety of the Tunnel and the adjoining site of the Tunnel Adit portal. IRCON regularly takes all necessary precautions at all work sites of the Project to ensure the safety of the work and workers.

The slope failure at the Access Tunnel Portal area was caused by a combination of natural geological conditions and weather events. Stabilisation beyond the cut slope that generated the thrust is further needed to prevent the repetition of this kind of unfortunate incident, said IRCON in a press release.

- ANI