Larsen & Toubro (L&T) Construction has announced simultaneous breakthroughs in Diversion Tunnel-4 (DT-4) and Diversion Tunnel-5 (DT-5) at the Dibang Multipurpose Project in Arunachal Pradesh, India.
The milestones were achieved on 28 April 2026 by the company’s Heavy Civil Infrastructure (HCI) business. The twin daylighting blasts mark the completion of breakthroughs in three of the project’s five diversion tunnels, following the earlier completion of DT-3 in February.
The 2880MW Dibang Multipurpose Project, being developed by NHPC in the Lower Dibang Valley, is one of India’s largest hydroelectric developments.
According to L&T, coordinating simultaneous tunnel breakthroughs in the Himalayan region presented significant geological and environmental challenges. The final blasts were attended by NHPC Executive Director Narender Kumar, who commended the project team’s performance.
L&T’s Lot-02 contract includes construction of a 37km access road network, two permanent bridges and five diversion tunnels with a combined length of 6.4km.
The diversion tunnels are a critical component of the project’s river diversion works, enabling construction of the main dam structure.
