The project adopts a long-term cost-benefit approach: higher upfront technical costs now, but reduced future disruption and maintenance expenses over its lifespan.

India plans two new deep underground rail alignments in the Siliguri Corridor, or the Chicken’s Neck, to safeguard land connectivity between the northeast and the rest of the country.

Surface upgrades will accompany the underground lines, creating a multi-track system designed to provide uninterrupted access to the Northeast and bolster military logistics, energy infrastructure, economic trade, and highway connections.

The proposed route spans about 40 kilometers from Tin Mile Haat to Rangapani, at a depth of 20–24 meters to resist detection and threats, while surface tracks are upgraded to form six-line capacity when integrated with the underground section.

The project is framed as a deterrent and resilience measure, signaling that disruption of the corridor would be difficult, drawing comparisons to border-hardening infrastructure in nearby regions.

The initiative complements surface rail expansions, creating a layered, redundant network to maintain operations if one route is disrupted.

The underground railway fits a broader strategic shift to treat infrastructure as a protective asset, aligning with regional policy objectives and ensuring long-term connectivity for tens of millions of residents despite geopolitical threats.

Operational resilience and military logistics are central goals, ensuring secure movement of troops, equipment, and supplies even under threats.

Deeper tunnels, at roughly 20–24 meters below ground, are chosen because surface expansion alone is insufficient for survivability and tunnels reduce vulnerability to modern weapons and facilitate rapid restoration after incidents.

Geopolitical and security considerations near international borders drive the prioritization of a hardened corridor.

India’s intent is to transform a historically vulnerable stretch into a robust, multi-path transport artery capable of withstanding natural and man-made shocks.

Implementation faces challenges like complex geology, high water tables, and seismic activity, requiring advanced tunneling technology and methods such as specialized tunnel boring machines for long-distance use.