Assam Chief Minister Dr Himanta Biswa Sarma informed on Wednesday that a new under the Brahmaputra river in Assam will be built. It will be another strategic tunnel similar to Atal Tunnel. It will be important for the speedy movement of its vehicles,

The tunnel will be around 12-15 kilometers long.

https://www.indiatoday.in/india/story/indian-army-planning-to-make-tunnel-under-brahmaputra-river-himanta-biswa-sarma-1839789-2021-08-12