Tracing the Evolution of Tunnelling in India
Dinesh Chand Deshwal, Commissioner-Railway Safety (Northern Circle), Ministry of Civil Aviation, Govt of India, delves into the history of tunnelling in India, tracing its evolution from early hand-drilled techniques to modern, technology-driven approaches, and underlines the increasing role of tunnelling in metro rail projects and the need for capacity building.
Tunnelling has always been one of the most challenging aspects of infrastructure development. Despite our best efforts, it is impossible to entirely eliminate the risk of failure due to unforeseen geological conditions. Historically, tunnel construction in India dates back to the early days of railway construction. The first railway line, connecting Bolivar and Thane, was established in 1853. To extend connectivity to the Northeast and Southeast, tunnelling in the Western Ghats became necessary.
In those early days, engineers used hand drills and black powder explosives to create tunnels on the Mumbai-Pune and Mumbai-Nasik rail alignments. Working with rudimentary survey instruments, it was challenging to ensure that tunnels excavated from both ends met accurately in the center. Today, the industry has advanced significantly, employing state-of-the-art technology and equipment such as tunnel boring machines, robotic shotcrete machines, and fully automatic drilling and jumbo machines.
In contemporary India, large-scale tunnelling in metro rail projects has become a major contributor to infrastructure development, alongside significant advancements in railways and highways. The power sector has also played a crucial role in enhancing tunnelling technology in the country.
As the rail network expanded across India, tunnelling was carried out in the Western Ghats, the Deccan Plateau, and other ranges. However, tunnelling in the Himalayas was not ventured into until the turn of the 20th century. The challenging terrain and geological conditions in the Himalayas meant that broad gauge rail networks were almost non-existent in Uttarakhand, Himachal Pradesh, and Jammu and Kashmir. To provide reliable transportation to Jammu and Kashmir, the Government of India initiated the rail link project from Jammu to Baramulla, connecting the Kashmir Valley to the Indian Railway network.
The effort to complete rail connectivity to the Kashmir Valley has been a long struggle of over 20 years. The geological challenges in the lower Himalayas are unparalleled, with a landscape full of thrust faults, perched aquifers, and landslides. However, the successful completion of the Udhampur-Srinagar-Baramulla rail link project is imminent and will build confidence for future projects in the Himalayan region. Modern technology now allows for the construction of longer and deeper tunnels to circumvent geographical issues.
Notably, the USBRL project includes approximately 120 km of tunnels, featuring the longest transportation tunnel in the country, measuring about 13 km. This tunnel is already operational between Banihal and Sangaldan. Similarly, the Rishikesh-Karnaprayag rail project, undertaken by Indian Railway PSU RVNL, will involve a 15-km-long tunnel, the longest of its kind.
There are numerous rail connectivity projects in the pipeline for hilly regions, aimed at enhancing strategic connectivity and meeting regional aspirations. With the technology and expertise available, many more projects involving longer tunnels are expected in Uttarakhand, Himachal Pradesh, and Jammu and Kashmir.
Despite advancements in technology, capacity remains a constraint. It is crucial to augment capacity and encourage infrastructure companies to invest in skilled manpower and specialized machinery.
Several important issues need to be addressed in tunnel construction. First, integration at the planning stage is critical. Cost-effectiveness and value for money must be prioritized to avoid unnecessary expenditures that could undermine the project's objectives.
Safety provisions are essential, particularly in longer tunnels. We should explore optimizing tunnel usage by planning for multi-purpose applications. For instance, escape tunnels could also be used for regular road or rail services, rather than being reserved solely for emergencies. Coordination at the planning stage is essential for this.
Design is another crucial factor. All stakeholders must ensure accountability and high-quality engineering consulting services. The success of tunnel construction relies heavily on the DPRs and other reports provided by engineering consultants. Strata geology is a key factor, and safety protocols during construction must be strictly followed. Early assessment of strata is crucial for safety and efficiency, and significant R&D investment is needed in tunnelling technologies. Extensive studies of the Himalayas and its geological features are necessary to address terrain-related challenges. Modern techniques for predicting stratification must be calibrated for the Himalayan region.
Recent large-scale tunnelling projects, involving significant diameters and lengths, have generated valuable experience and knowledge. It is time to establish a Center of Excellence for tunnelling in the Himalayan region to concentrate and disseminate this knowledge for future projects. Developing a best practices manual before project execution and conducting extensive investigations and design detailing is essential.
To achieve policy changes and engineering excellence, focusing on positive changes is crucial. We should also strategize to utilize the data and information already gathered by various departments. For example, the Indian Railway’s Kashmir project and the border road work have provided significant engineering insights. Institutionalizing this knowledge and ensuring better coordination across projects will enhance tunnelling efforts in the Himalayas.
