Tech wiz and market disruptor Elon Musk is looking to revolutionize how underground tunnels are made, with an eye to building underground transit networks which could decongest cities:
Musk is has targeted this particular sector because he feels it's ripe for innovation and disruption, since the technology hasn't advanced in over half a century. India should look at applying any revolutions in this field towards improving its own infrastructure.
I know Rajeev feels urban concentrations go against India's traditional village existence, but on the other hand, big cities can function more efficiently by concentrating large numbers of people in close proximity to infrastructure and resources. "3D cities" could enable more people to live within close proximity of work to ease their commute, while also making more efficient use of mass transit. Previously it was the rise of the automobile and cheap gas which facilitated suburban sprawl, while in the future the opposite scenario may be favored.
Additionally, India has some of the highest mountainous regions in the world, located in remote and highly disputed boundary areas. The ability to tunnel deeply into mountainsides could help in creating more fortified and impregnable defenses, as well as in improving logistical transport supply lines to these remote areas.