The NATM-built tunnel near the village of Zaroli in Gujarat is 350m-long, has a 12.6m diameter and a height of 10.25m. It is a single tube horseshoe shape and will house two tracks. It was excavated in 10 months.

It is the first of seven mountain tunnels to be built by NATM on the route.

Tunnel construction included marking drill holes on the tunnel face, drilling of holes, charging of explosives, controlled blasting, muck removal, and installation of primary support including steel ribs, lattice girder, shotcrete and rock bolts.

The 508km Mumbai-Ahmedabad High-Speed Rail project, also called the MAHSR Bullet Train project, will connect Mumbai with Ahmedabad in Gujarat. It consists of 465km of viaducts, 12 stations, three rolling stock depots, 28 steel bridges (including a 2km bridge over Vaitarna river), and nine tunnels, including India’s first undersea tunnel. The 7km subsea section is part of a 21km tunnel between Bandra-Kurla Complex and Shilphata in the state of Maharashtra.

The National High Speed Rail Corporation (NHSRCL) has awarded several packages to Larsen & Toubro, including package C-3 which includes a 135km alignment from Shilphata to Zaroli village comprising 124km of viaducts and bridges, six mountain tunnels, 36 crossings (including 12 steel bridges), and three elevated stations, the civil and building works packages C-4 (237km); C-5 (8.2km); and C-6 (87.5km); and the ballastless trackworks package T-3.