Atal Tunnel (Rohtang)

Atal Tunnel is the world's longest highway tunnel above 10,000 feet altitude — a 9.02 km single-tube tunnel under the Rohtang Pass connecting Manali (Kullu valley) to Sissu (Lahaul valley) in Himachal Pradesh. Opened by Prime Minister Modi on 3 October 2020, the tunnel provides year-round road access to the Lahaul valley, which was previously cut off for 6 months each winter when the 3,978 m Rohtang Pass road was buried in snow.

Named after Atal Bihari Vajpayee, the BJP Prime Minister whose government sanctioned the project in 2002, the tunnel took 18 years from sanction to commissioning — beset by Himalayan geology surprises (water ingress, rock-burst events, Seri Nala dry-rock fault zone), funding gaps, and Border Roads Organisation contractor changes.

Construction was executed by AFCON-Strabag JV using the New Austrian Tunnelling Method (NATM). The tunnel is horseshoe-section, 10.5 m wide × 5.525 m high carriageway, with reinforced concrete lining 30-40 cm thick throughout. A parallel emergency egress tunnel runs the entire 9.02 km length on the south side.

The tunnel cuts Manali-Lahaul travel from 5 hours to 10 minutes and reduces the road distance by 46 km. Strategically, it provides year-round military access to Ladakh via Leh — a critical capability after the 2020 Galwan standoff. Daily traffic averages 4,500 vehicles in summer, 1,500 in winter.