Major Tunnels of Nepal: Nagdhunga, Siddhababa & Fast Track Directory

For a country whose highways climb and switchback across the Mahabharat and Chure ranges, Nepal came remarkably late to road tunnelling. Until the 2020s, not a single modern highway tunnel existed anywhere in the country: every vehicle entering Kathmandu from the west still crawled over the congested, landslide-prone Nagdhunga pass. That changed with what Nepali media now call the 'tunnel era' — the Japanese-funded Nagdhunga–Sisnekhola Tunnel on the Tribhuvan Highway, the Siddhababa Tunnel on the Siddhartha Highway, and seven tunnels being driven on the Kathmandu–Terai/Madhesh Fast Track expressway, alongside major water tunnels such as Melamchi, Bheri–Babai and Sunkoshi–Marin.

This page is a directory of every major tunnel — operational, under construction and planned — with its length, highway, builder or donor, cost and current status. Two quick answers for common searches: the first tunnel in Nepal is the historic Churia Tunnel of 1917 (1974 BS), while the first modern road tunnel is Nagdhunga; the longest tunnel of any kind is the roughly 26-km Melamchi water-supply tunnel, and the longest road tunnel is Nagdhunga's 2,688-metre main tube.

The Nagdhunga–Sisnekhola Tunnel, universally known as the Nagdhunga Tunnel, is Nepal's first modern highway tunnel. Its main tube is 2,688 metres long and carries two lanes (about 9.5 metres wide), with a parallel 2,557-metre evacuation tunnel for emergencies. It runs beneath the Nagdhunga pass on the Tribhuvan Highway, connecting Sisnekhola in Dhading district with the Balambu–Satungal area of Chandragiri Municipality, Kathmandu — the capital's main western gateway, through which most goods and passengers from the Terai, Pokhara and India funnel every day.

The project is financed by a concessional loan of about Rs 16 billion from the Japan International Cooperation Agency (JICA), within a total project cost of roughly Rs 22 billion including land acquisition, approach roads and bridges. Japan's Hazama Ando Corporation is the contractor, with Japanese consultants supervising. Construction formally began on 21 October 2019 with a 42-month deadline (April 2023), but difficult geology — including several shear zones — and the Covid-19 pandemic pushed the deadline back repeatedly. The evacuation tunnel achieved breakthrough on 7 August 2023, and the main tunnel broke through on 15 April 2024.

By April 2026 the project stood at about 98 percent completion, and the government signed a five-year operation and maintenance contract with Yusin–ART JV, a China–Nepal joint venture, which is required to bring the tunnel into service within three months of the agreement — meaning full traffic operation in mid-2026 after trial runs and training of roughly 150 operating staff. Tolls will be collected at plazas on both portals and deposited into the Roads Board Nepal account, with annual operating costs estimated at around Rs 300 million.

The payoff is dramatic for such a short tunnel: the Balambu–Sisnekhola road distance drops from about 7.5 km to 5 km, and the uphill crawl over the pass — about 33 minutes in normal traffic, and often hours in jams — falls to roughly 7 minutes. The tunnel also gives Kathmandu a reliable, all-weather lifeline that keeps functioning when monsoon landslides or earthquakes block the old pass road.

The Siddhababa Tunnel is being built on the Siddhartha Highway between Butwal and Tansen (Palpa), where the road squeezes through the Tinau River gorge below the Siddhababa temple. This roughly four-kilometre stretch between Dobhan and the temple is notorious for year-round rockfalls and landslides that have crushed vehicles and killed travellers, forcing frequent closures. The tunnel is the permanent fix: once open, traffic to and from the hill districts of Lumbini and Gandaki provinces — Palpa, Gulmi, Syangja, Arghakhanchi, Baglung and Parbat — will no longer pass under the crumbling cliff face.

The main tunnel is 1,126 metres long with a double-lane, 8.5-metre-wide carriageway and sidewalks, supported by three shorter bypass/evacuation tunnels of 151, 161 and 130 metres, all of which have been excavated. China State Construction Engineering Corporation won the contract on 17 February 2022 at a cost of about Rs 7.34 billion, financed by the Government of Nepal's own budget — a point of national pride, as it is among the first tunnels Nepal is building without donor funding. The main tunnel achieved breakthrough on 24 January 2025 (Magh 2081 BS).

Progress since the breakthrough has been slower than hoped: physical progress reached about 65 percent by late December 2025, with electromechanical systems — ventilation, lighting, fire safety — plus access roads, slope protection and retaining structures still to finish. The contractual completion deadline is 22 March 2027, and officials have talked of opening the tube to traffic earlier if finishing works accelerate.

The Kathmandu–Terai/Madhesh Fast Track is Nepal's largest infrastructure project: a 70.977-km expressway from Khokana (Lalitpur) to Nijgadh (Bara) that will cut the Kathmandu–Terai drive to about an hour. The Nepali Army has managed construction since the government handed it the project in May 2017, with Chinese contractors including China State Construction Engineering and Poly Changda building the most complex packages. The revised cost is about Rs 213 billion, with a completion target of the end of Chaitra 2083 BS (mid-April 2027) — a deadline officials concede is at risk. Overall progress reached about 45 percent by January 2026.

The alignment includes tunnels at seven locations totalling around 10.9 km — by far the largest concentration of road tunnels in Nepal, most of them twin-tube so that each direction of traffic gets its own tunnel. Breakthroughs were achieved at Lendanda (17 May 2024) and Dhedre (first tube, 24 May 2024), while the 3,455-metre Mahadevtar (Mahadev Danda) tunnel in Makwanpur — set to become Nepal's longest road tunnel — was targeting its first-tube breakthrough by mid-2026. The four shorter tunnels added in design revisions are in the portal-construction and finishing stages.

Long before Nagdhunga, Nepal built a tunnel with hand tools. The Churia Tunnel, about 500 metres long, was driven through the Churia (Chure) hill on the border of Makwanpur and Bara districts in 1917 (1974 BS), during the premiership of Chandra Shumsher Rana. Its project chief was Dilli Jung Thapa, regarded as Nepal's first civil engineering graduate. The tunnel carried the country's first motorable cart road between Amlekhganj in the Terai and Bhimphedi, the staging post from which goods and even dismantled motor cars were portered over the hills into the Kathmandu Valley on the old Raxaul trade route.

The tunnel remained in use until the early 1960s, when the Tribhuvan Highway alignment bypassed it, and it slipped into obscurity. Later declared a site of historical importance, its surviving section — about 225 metres after restoration — was rebuilt by the Bagmati Province government for around Rs 45.7 million and reopened to visitors in 2024. It stands near the Churiyamai temple off the East–West Highway on the outskirts of Hetauda.

The 'longest tunnel in Nepal' has different answers depending on the type. The longest tunnel of any kind is the Melamchi Water Supply Project tunnel, about 26 km from the Melamchi River in Sindhupalchok to Sundarijal on the Kathmandu Valley rim. Its excavation breakthrough came on 12 April 2018 after nearly two decades of stop-start work, and Melamchi water first flowed to Kathmandu in 2021. Built with Asian Development Bank (ADB) support, it is among the longest water-supply tunnels in Asia.

Nepal's two tunnel-boring-machine (TBM) records also belong to water projects. The Bheri–Babai Diversion Multipurpose Project drove a 12.2-km irrigation tunnel through the Chure hills in Surkhet — Nepal's first TBM tunnel, broken through in April 2019 a year ahead of schedule. The Sunkoshi–Marin Diversion Multipurpose Project surpassed it with a 13.3-km, TBM-bored tunnel that broke through on 8 May 2024, eleven months early; it will divert Sunkoshi water into the Bagmati basin for Terai irrigation and a 28.6 MW powerhouse. Among road tunnels, Nagdhunga's 2,688-metre main tube is the longest completed, a record the 3,455-metre Mahadevtar tunnel on the Fast Track will take once it opens.

The most prominent proposal is the Tokha–Chhahare Tunnel, an approximately 4.2-km tunnel under the Shivapuri ridge linking Tokha in northern Kathmandu with Chhahare in Nuwakot, which would slash the climb out of the valley on the Kathmandu–Rasuwagadhi trade corridor to China. It featured in the memorandum of understanding signed during Chinese President Xi Jinping's October 2019 (Ashoj 2076 BS) visit, and Nepal allocated about Rs 1 billion in FY 2080/81 (2023/24) for its detailed study; China has since sent a draft implementation agreement to conduct the detailed feasibility study under grant assistance. Construction, however, has yet to be scheduled.

Beyond Tokha–Chhahare, the government has listed more than a dozen tunnel and underpass projects in recent budgets — the FY 2024/25 budget spread roughly Rs 810 million across 14 of them, an amount experts criticised as token. Most remain at the study or detailed project report (DPR) stage, so lengths and costs are indicative until contracts are signed.

Nepal's first generation of road tunnels has delivered engineering success alongside chronic schedule slippage. Nagdhunga's deadline was extended four times, from April 2023 to May 2026, and even after physical completion the opening waited months for an operator to be procured — a reminder that Nepal is building not just tunnels but the institutions to run them, from tolling to ventilation management and emergency response. Siddhababa has likewise slowed in the finishing phase, and the Fast Track's April 2027 target is widely expected to slip again.

Still, the direction is clear. Within roughly a year of mid-2026, Nepal expects its first tolled highway tunnel operating at Nagdhunga, Siddhababa nearing completion, and multiple Fast Track tunnels finished. Follow the Department of Roads (dor.gov.np), JICA Nepal and the Nepali Army's Fast Track updates for authoritative progress reports, and treat planned-tunnel figures as provisional until DPRs and contracts are finalised.