Deep underground: How India is building world’s longest tunnel — Telangana's SLBC project (in pictures)

The SLBC tunnel, spanning 43.93 km, is India’s longest tunnel project. advanced mechanized excavation ensures precise alignment and reduces manual risks. sensors monitor rock pressure, soil stability, and vibrations continuously. reinforced linings and rock bolts stabilize sections under high stress. water ingress management protects against flooding. ventilation and lighting systems maintain safe conditions. automated systems track excavation speed and efficiency. geotechnical modelling predicts weak zones ahead. smart technologies enhance long-term structural reliability.

The project budget has risen to Rs 4,600 crore due to inflation and past delays. revised allocations cover advanced technology, safety equipment, and skilled workforce. strict expenditure tracking prevents overruns. high-quality material procurement ensures durability. contractors are accountable for deadlines. phased execution allows better cost control. audits maintain transparency and adherence to norms. financial planning incorporates contingency for unforeseen challenges. overall strategy targets efficient, timely completion of the tunnel.

Once completed, the tunnel will undergo thorough testing for structural stability and water flow. hydraulic, electrical, and ventilation systems are verified before operational use. emergency protocols are rehearsed and optimized. maintenance teams are trained for long-term reliability. sensors provide real-time monitoring of tunnel conditions. communication systems link the tunnel with control centers. contingency plans ensure uninterrupted service. phased commissioning follows technical clearance. the project sets a benchmark for large-scale, secure tunnel operations.

Chief minister A Revanth Reddy vowed to expedite the SLBC tunnel and blamed the previous BRS govt for delays and cost escalation. originally pegged at Rs 2,000 crore, the project now costs Rs 4,600 crore. it aims to deliver 30 tmc of Krishna water for irrigation and drinking purposes. the cm stressed completion is critical for Nalgonda and Mahabubnagar residents. technical and Army experts oversee progress, ensuring safety. families of deceased workers are supported by government schemes. geophysical and hydrological surveys guide excavation. strict supervision ensures adherence to schedules. the cm emphasized the project is a top priority for the state. (Picture credit: Roushan Ali)

Specialized Army personnel and NGRI experts are actively guiding tunneling operations. army officers train construction teams in risk mitigation and emergency response. NGRI specialists monitor soil, rock, and subterranean water conditions. insights help adjust excavation methods in real time. advanced technology aids detection of unstable zones. combined expertise ensures operational safety and efficiency. supervision minimizes human and structural risks. lessons from past accidents are incorporated into protocols. ongoing monitoring guarantees adherence to global tunneling standards.

Enhanced safety protocols protect personnel during tunneling. protective gear, ventilation, and real-time monitoring are mandatory. regular drills simulate emergencies for preparedness. risk assessments are conducted frequently, covering collapse, water ingress, and fire hazards. psychological support and insurance are provided to teams. strict supervision ensures compliance with international safety standards. safety equipment is regularly inspected and upgraded. emergency exits and shelters are strategically placed. preventive measures aim to maintain zero-casualty operations.

The tunnel will divert 30 tmc of Krishna water to irrigate three lakh acres and supply safe drinking water to fluoride-affected regions. distribution networks are designed for optimal flow and minimal losses. monitoring systems track water quality and quantity continuously. reservoirs and pipelines support uninterrupted delivery. communities in Nalgonda and Mahabubnagar benefit from equitable access. emergency storage ensures availability during maintenance. the project enhances crop yields and rural livelihoods. local management teams supervise daily operations. it establishes a long-term water security framework for Telangana.

Environmental protection is integrated into construction planning. flora, fauna, and aquifers are monitored to minimize ecological disruption. relocation and compensation programs support affected communities. dust, noise, and vibration mitigation measures are in place. waste and excavation debris are managed systematically. environmental compliance is continuously tracked. public engagement ensures awareness about benefits and safety measures. ongoing monitoring mitigates long-term ecological risks. construction methods are adjusted to minimize habitat impact.

The SLBC tunnel will transform Telangana’s irrigation and water supply infrastructure. reliable water access improves agriculture, drinking water, and socio-economic growth. technical expertise and modern construction methods enhance state engineering capacity. nearby regions benefit from employment and skill development. the project strengthens climate resilience and drought mitigation. community health and livelihoods improve with safe water supply. government monitoring ensures sustainability. advanced technology adoption positions Telangana as a model for tunnel projects. project completion promises enduring regional prosperity.

A helicopter-borne VTEM plus magnetic survey maps shear zones and underground water along the tunnel alignment. real-time monitoring by officials and experts ensures precision. data guides excavation techniques and reinforces weak sections. electromagnetic surveys identify water pockets to prevent seepage. aerial observation minimizes risks to personnel on the ground. survey results allow fine-tuning of tunneling speeds. high-resolution mapping reduces chances of geological surprises. survey outcomes feed into safety and operational planning. all findings support efficient and secure construction.