Telangana's Srisailam Left Bank Canal (SLBC) tunnel project has moved past a critical geological obstacle, with excavation clearing the formidable shear zone and setting the stage for faster progress, state Irrigation and Civil Supplies Minister N. Uttam Kumar Reddy announced on Sunday, 4 October 2026. The breakthrough is expected to accelerate construction on the 43.968-km main tunnel, which remains the lifeline for over 30 TMC of water supply to the drought-prone upland areas of the erstwhile Nalgonda region.

Key Developments at the Tunnel Face

The 43.968-km main tunnel is approximately 79% complete, with roughly 9.1 km of excavation still remaining. The project team recorded a combined daily advance of about eight metres, with a sustained rate of seven to seven-and-a-half metres per day — peaking at ten metres on select days. Over the preceding five to six months, the tunnel advanced approximately 700 metres in total, comprising around 450 metres from the outlet and 250 metres from the inlet, which included the carefully negotiated passage through the major shear zone.

A construction cycle that previously took roughly 48 hours has been cut to 20–24 hours. With improved equipment and faster material removal, the team anticipates reducing that cycle further to approximately ten hours, with accelerated progress expected from late October or early November.

Engineering Solutions to Geological Challenges

Col. Parikshit Mehra, an Indian Army tunnel expert leading operations, explained that excavation at the inlet was deliberately slowed during initial months due to weak ground, rock bursts, and the need to prevent a repeat of past accidents. To negotiate the unstable stretch, the team installed 140-mm seamless pipes to form an umbrella canopy ahead of the excavation face. Reinforced ribs, staged excavation, probe drilling, and additional structural support measures were employed to control risks as crews worked more than 20 km inside the tunnel.

The diversion around the point where the tunnel-boring machine had become stuck required passage through particularly challenging geological conditions. Improving rock quality is now enabling a gradual return to normal working conditions deep within the tunnel.

Equipment Deployment and Logistics Constraints

A three-arm drilling boomer is already operational at the outlet, where progress is reported to be near the required pace. A second three-arm boomer is expected at the inlet in October. Electric loaders and advanced excavators are also supporting construction. A locomotive ordered from Germany is expected by the end of October; its deployment is anticipated to significantly improve the removal of excavated material and shorten the construction cycle.

Hauling excavated material over distances of up to 21 km remains a critical bottleneck. When removal falls behind, material accumulates inside the tunnel, eventually forcing work at the face to halt until the backlog is cleared — a constraint that the incoming locomotive is specifically designed to address.

Safety and the Road to June 2028

The safety focus at the project has been heightened since eight workers were killed during tunnel excavation in February 2025 — a tragedy that prompted a more cautious and methodical approach to geological risk management. Minister Uttam Kumar Reddy directed officials and the contractor to build on the progress made through the difficult geological stretch while maintaining rigorous safety protocols for crews working deep underground.

The minister held a marathon review with elected representatives and senior officials from the three districts of erstwhile Nalgonda, pressing for a credible, closely monitored programme to achieve the June 2028 water-delivery goal. The meeting was attended by MPs K. Raghuveer Reddy and Chamala Kiran Kumar Reddy, several MLAs, MLC Shankar Naik, Irrigation Secretary E. Sridhar, Engineer-in-Chief O. V. Ramesh Babu, and collectors from Suryapet, Nalgonda, Yadadri-Bhongir, and Mahabubabad.

With the geological barrier behind it and fresh equipment en route, the project's ability to hit its June 2028 deadline will hinge on whether the supply chain, logistics, and safety management can sustain the accelerated pace through the remaining 9.1 km.