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• Length: 9.02 km (5.6 mi)
• Shape (cross-section) of Tunnel: Horseshoe
• Finished width: 10.00 m (32.8 ft) at road level. (8m pavement and 1m footpath on both sides)
• The general altitude of the tunnel: 3,000–3,100 m or 9,840–10,170 ft
• Geology of tunnelling media: Uniformly dipping alternate sequence of quartzites, quartzitic schists and quartz-diorite-schist with thin bands.
• Tunnel boring machines were not used because of the inability to see inside the mountain, instead blasting and digging were used to build the tunnel.
• Construction technique: Drill & Blast with NATM
• Support system: Fibre-reinforced concrete (100–300mm or 0–10 inch thick) combined with rock bolt (26.50mm dia, 5,000–9,000mm or 200–350 inch long) has been used as the central support system.
• Tunnel ventilation: Semi-transverse system of ventilation.
• A 2.25 m high and 3.6 m wide emergency tunnel is integrated into the tunnel cross-section beneath the main carriageway.

The following parameters have been set in the design:

• Upper tolerance limit for concentration – 150ppm
• Visibility factor – 0.009/m
• Vehicles
  • Cars – 3000 Nos.
  • Trucks – 1500 Nos.
• Peak hour traffic – 337.50 PCUs
• Design vehicular speed in Tunnel
• Maximum Speed – 80 km/h (50 mph)
• Minimum Speed – 30 km/h (19 mph)
• Project Cost: Approximately ₹3,200 core

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Atal Tunnel (also known as Rohtang Tunnel), named after former Prime Minister of India, Atal Bihari Vajpayee is a highway tunnel built under the Rohtang Pass in the eastern Pir Panjal range of the Himalayas on the National Highway 3 in Himachal Pradesh, India. At a length of 9.02 km, it is the highest highway single-tube tunnel above 10,000 feet (3,048 m) in the world. With the existing Atal Tunnel and after the completion of the under-construction Shinku La Tunnel, which is targeted to be completed by 2025, the new Leh-Manali Highway via Nimmu–Padum–Darcha road will become an all-weather road.

The tunnel reduces the travel time and overall distance between Manali and Keylong on the way to Leh. The route, which previously went through Gramphu, was 116 km (72.1 mi) long and took 5 to 6 hours in good conditions. A traveller now reaches the South Portal of the tunnel from Manali, a distance of 24.4 km (15.2 mi) in about 45 minutes, goes through the 9.02 km (5.6 mi) long tunnel in about 15 minutes, and reaches Keylong which is 37 km (23.0 mi) away in about 60 minutes. The new route via the tunnel brings down the total distance travelled to 71 km (44.1 mi) which can be covered in about 2 hours, a reduction of around 3 to 4 hours when compared to the earlier route. Moreover, the tunnel bypasses most of the sites that were prone to road blockades, avalanches, and traffic snarls.