India’s tunnelling sector has witnessed unprecedented expansion, with currently over 700 tunnels in the pipeline across various stages and sectors. The growth has primarily been driven by a robust pipeline of projects as well as investments in developing hydropower projects, enhancing urban mass transit networks, augmenting road and rail interconnectivity, constructing underground crude oil repositories, and upgrading water supply and sewerage systems. In line with this rapidly growing project pipeline, increasing traffic volumes and utility of tunnels, advanced and effective safety measures and systems have become critical in tunnel design. Despite this awareness, there have been tunnel collapses. This has raised critical questions about safety protocols, implementation gaps and whether substantial funding allocation translates into actual worker protection.
Current safety practices
As the number of tunnels being constructed keeps rising and the traffic volume in existing tunnels grows, safety measures are assuming greater importance. The development of safe tunnels necessitates the consideration of a diverse array of factors. Every aspect, ranging from the tunnel design, ventilation system and lighting to firefighting procedures, plays a crucial role in ensuring the safety of labour as well as travellers.
Current safety practices integrate advanced surveillance and monitoring technologies. Artificial intelligence (AI)-enabled systems perform vehicle identification through number plate detection, optical character recognition, face detection and helmet detection. Firefighting systems being deployed use high-pressure water mist with small droplets, providing greater coverage and superior cooling. Another essential safety consideration is the design of tunnel lights. It is essential to consider factors such as the black hole effect at the entrance, the glare effect at the exit and sufficient reaction time/stopping distance when a hazard is identified. Electrically powered equipment, noise control mechanisms, robotic excavators (used in the Mumbai Metro) and electric drum cutters are a few of the sustainable measures that have the potential to be scaled up.
In key recent examples, facial recognition systems have been activated by the Jammu & Kashmir Police, which include AI-based facial recognition systems with CCTVs near tunnel entrances on the Jammu-Srinagar highway. Additionally, Intozi’s AI video analytics implemented at L&T’s ADIT-2 tunnels enable vehicle detection, helmet detection and attendance tracking via face matching. Fire hydrants have also been placed every 60 metres in the Atal (Rohtang) Tunnel, enhancing emergency response capacity. Ventilation systems now integrate variable frequency drives (VFDs), with Danfoss installing over 1,500 VFDs across Delhi, Chennai, Bengaluru, Mumbai and Pune metros and Kolkata’s underwater tunnel. The Z-Morh tunnel features 710 kW VFDs in jet fans, allowing swift airflow reversal, while the Dr Syama Prasad Mookerjee tunnel became India’s first tunnel with a fully transverse ventilation system. Additionally, safety audits continue, with the National Highways Authority of India conducting assessments of 29 under-construction tunnels (12 in Himachal Pradesh, 6 in Jammu & Kashmir).
Emerging solutions
With the increasing importance of safety in tunnelling, many initiatives are under way. Advanced technologies transforming tunnel safety include digital twins that provide high-resolution data for rock bolt monitoring, loose fall location and overbreak/underbreak analysis. Drone-based light detection and ranging (LiDAR) enables void/cavity detection and crack evaluation as an early warning system. AI facial recognition improves security near tunnel entrances through enhanced access control. Building information modelling provides centralised data platforms for mechanical, electrical and plumbing (MEP) network alignment. Computerised excavation rigs with two/three-boom configurations enable automation for sustainable tunnelling. Materials, including mechanical single bolts, expanding friction bolts, self-drilling rock bolts and steel/fibre-reinforced polymer anchors, are increasingly used by contractors. Monitoring solutions include customised systems that continuously map concrete coverings and reinforced bars, identifying cavities, fractures, voids, delamination and water permeation.
Highlighting the lack of safety measures for workers
Tunnelling remains inherently high-risk due to formidable geological intricacies, particularly in regions such as the Himalayas and the Western Ghats. In November 2023, the Silkyara-Barkot tunnel collapse in Uttarakhand trapped 41 construction workers for 17 days, requiring a massive rescue operation that involved rat-hole miners from Manipur. Following this, in December 2024, a tunnel collapse on the Delhi-Mumbai Expressway in Kota killed one worker and injured three others when a portion of the under-construction eight-lane green corridor collapsed. Another collapse occurred in Nagarkurnool district, Telangana, within the Srisailam Left Bank Canal project, trapping eight engineers and labourers inside the tunnel. About 50 workers were inside when part of the ceiling caved in following a sudden inflow of water and mud, and 43 managed to escape. Prior to this, an under-construction flyover near the Nanganallur Thillai Ganga Nagar tunnel in Chennai collapsed. A portion of the tunnel on the Jammu-Srinagar Highway collapsed, blocking the vital transportation route for hours. Such incidents have highlighted safety lapses, structural flaws and the quality of tunnel construction practices.
These multiple catastrophic collapses have occurred despite substantial financial commitment for tunnel construction across all sectors. This funding paradox also raises a critical question: If substantial funds are being allocated, why do safety failures persist? The answer lies not in fund availability but in implementation gaps, unclear contract norms and inadequate safety audits.
Worker safety is paramount because tunnelling involves excavation in unstable geological formations where oxygen depletion, fire hazards, smoke circulation and high energy consumption create dangerous working conditions.
Personal protective equipment alone cannot prevent structural collapses, and hyperbaric interventions require continuous monitoring of worker conditions. Experience in the Indian subcontinent demonstrates that without adequate safety infrastructure, geological uncertainties can quickly become fatal disasters.
Making tunnels safer with better project design and planning
Tunnel safety must begin at the design and planning stage through comprehensive geotechnical investigations. The Ministry of Road Transport and Highways (MoRTH) has issued comprehensive safety guidelines following the Silkyara collapse, establishing new regulatory frameworks. It released the “Tunnel Alignment Studies” guidelines on September 2, 2025, the “Prevention and Mitigation of Road Tunnel Collapses” guidelines on December 5, 2025, and standard operating procedures for “Hazardous Material Vehicles” on January 27, 2026.
Key requirements mandate that geological maps and national landslide susceptibility mapping from the Geological Survey of India must be consulted during alignment surveys. Tunnel shapes must be evaluated for structural stability, not just space requirements. Environmental impact assessments are now mandatory for tunnel roads per MoRTH documents. Moreover, a safety audit team comprising experts from IITs (Roorkee, Ropar and Delhi) is being formed, and a world-class tunnelling centre is being established.
To put the importance of these mandates into perspective, the final report on the Silkyara collapse identified fundamental errors in detailed project report preparation, where alignment fixing did not meet basic tunnelling principles and addressed only 21 minor collapses. Other root causes include inadequate geological investigations where project authorities fail to verify correctness, low quality materials and redundant techniques leading to mechanical, electrical and plumbing (MEP) and heating, ventilation and air conditioning system failures.
Safety infrastructure requirements are equally critical. High-risk zones demand 0.9 m NP-4 escape pipes installed in tunnel inverts. Mobile rescue containers capable of accommodating 12 workers must be placed 150-300 m behind the tunnel face, providing at least 24 hours of oxygen, water and communication capabilities. Pedestrian cross-passages at 300 m intervals enable evacuation, while shift managers must be trained as first responders. Emergency response plans require weekly updates to address evolving conditions.
Monitoring and quality control protocols to ensure safety
Maintaining structural integrity requires continuous monitoring and comprehensive documentation to ensure the overall safety of the tunnel structure. Displacement magnitude, direction and key parameters must be documented systematically. Digital twins provide high-resolution data for monitoring rock bolts, locating loose fall areas and analysing overbreak/underbreak in real time; drone-based LiDAR technology enables the early detection of voids, cavities, cracks, water tables, humidity and leakages; while the Hovermap technology can scan long tunnel lengths in minutes for efficient underground mapping. These measures must come into play in full form.
Quality control frameworks prove crucial across all tunnelling projects. Advanced materials, including fibre-reinforced shotcrete, lattice girders, pipe-roof pre-support systems and self-drilling rock bolts, strengthen tunnel structures. Moreover, waterproofing membranes such as LOGICROOF V-GR FB SA used in the Rohtang tunnel prevent water infiltration.
The way forward
India’s tunnelling boom presents both an unprecedented opportunity and a significant challenge. The absence of dedicated safety units, unclear contract norms and inadequate geological investigations must be addressed. Critical actions needed include following global best practices in rescue operations, regular safety audits with IIT expert teams and domestic manufacturing of safety equipment. Technologies such as digital twins, AI, drones, LiDAR and refurbished tunnel boring machines offer pathways to safer, sustainable tunnelling. However, industry experts note that technology and expertise to build tunnel roads are still evolving in India. The path forward requires not just funding, but also rigorous implementation, transparent risk allocation and a worker-centric safety culture that prioritises human lives over project timelines.
Investment in modern safety equipment, including personal protective equipment and advanced machinery, will prove critical for high-risk actions. Digital advancements will ensure safety, quality and profitable returns through resource optimisation. Going forward, the focus must now shift towards the strict enforcement of safety laws through regular audits, worker training and awareness programmes, emergency preparedness and response drills, as well as benchmarking enhanced safety measures against international metrics.
Himanshu Tagore
