There has been a steady increase in the demand for tunnel construction across the infrastructure space due to the needs of diverse sectors such as railways, metro systems, roads, hydropower, and water supply and sewerage.
This poses new challenges for India’s civil engineers since the terrain can vary from densely populated cities, to undersea and under-river, to high-altitude, seismically active mountains. State-of-the-art technology and equipment must be inducted, labour skilled up and the right tunnelling methods chosen on a project-specific basis. Policymakers also need to take cognisance of the needs of the tunnelling segment to ensure that contracts are suitably delineated, tenders well designed and equipment and material costs optimised.
There have been major advances in technology although the induction of new methods is uneven. New tunnelling methods such as the New Austrian Tunnelling Method and tunnel boring machines are being deployed in many projects. These enable engineers to deal with difficult terrains and to tunnel in congested urban locales while causing minimum disruption. New construction materials such as emulsion-based and water gel-based explosives, higher quality cement and concrete reinforced with glued steel fibres and waterproofing materials such as geotextile membranes and polymers have become popular.
There is also an emphasis on building smart assets with integrated traffic control systems, video surveillance systems, wireless communications, entrance detection control systems, electrical fire signalling systems, SOS call boxes, etc. Technologies for better geological and geotechnical investigations are also being used. Aerial surveys, photogrammetry-based surveys and GPS-based systems with high accuracy levels help in mapping difficult terrains.
Policymakers need to review practices in several areas to ensure that the segment gets the support it needs to function with full efficiency. Tunnelling contracts tend to be opaque and poorly designed in terms of risk sharing. There are often ambiguities and unclear terms and conditions, with the roles and responsibilities of contractors and project developers not being explicitly defined. Deviations from contract conditions often cause disputes and this leads to a slowdown in project execution. Plus, of course, land acquisition difficulties and agitation by local citizens are common, as indeed these are in other types of infrastructure projects.
Better contract design and smoother land acquisition processes would undoubtedly help. It would also be beneficial to compare the tax structure applicable to local equipment and materials manufacturing, versus the customs duties on equivalent equipment imports. As of now, manufacturers complain that the tax structure makes local equipment more expensive than imports, and this anomaly should be addressed to encourage local manufacturing and domestic assembly.
There will be large and growing opportunities for tunnel construction over the next five years to a decade. The railway sector is increasing its network, building both high speed lines with ambitious undersea tunnels and connecting inaccessible regions in the Northeast and Jammu & Kashmir. Road building across the mountains presents another opportunity. Metro projects are in progress or on the drawing board across multiple cities. Sewerage and water supply systems and gas pipelines are also areas where tunnelling expertise is required. Given adequate policy support, the tunnelling segment could see steady growth in the years ahead.