Over 500 Kilometers of Tunnels Built in Nepal Over the Last Century: Locations and Safety Evaluations

A study by a non-governmental organization reveals that over 500 kilometers of tunnels have been constructed across Nepal to date.

Following the recent floods at Bhotekoshi, and the lack of updates for 15 consecutive days regarding individuals presumed trapped inside several hydropower tunnels and powerhouse structures, a nationwide debate has begun on the safety standards of Nepal’s tunnels.

Nepal’s first road tunnel was constructed in 1918 BS (1861-62 AD). During the construction of the road from Amlekhganj to Bhimphedi, engineers at that time conceived a 500-meter-long tunnel to cross the Churiyamai hill.

After half of the original tunnel was dismantled to build the Mahendra Highway, the remaining length is 226.8 meters. The Bagmati Province Government has preserved this tunnel section as a tourist attraction and observation point.

Following road tunnels, tunnel construction expanded into mining and hydropower sectors in Nepal. Presently, various types of tunnels are utilized for drinking water, irrigation, and sewage management.

According to the Nepal Tunneling Association, the majority of tunnels have been constructed for hydropower projects. The powerhouse of the Chilime Hydroelectric Project, where rescuers have tried to enter in recent days after the Bhotekoshi flood, lies inside a 250-meter-long underground tunnel structure.

Lawmaker and tunneling expert Mr. Shriram Neupane reported that rescue teams had progressed 105 meters inside the tunnel as of Thursday morning.

Ramhari Sharma, president of the association, states that approximately 460 kilometers of tunnels have been completed for hydropower projects in Nepal so far. He notes that daily progress adds 10 to 20 meters of new tunnels.

“The data we have collected is unofficial and was compiled by integrating information from relevant projects. According to this data, the country currently has over 550 kilometers of tunnels,” Sharma says, though he acknowledges the figures are not based on precise measurements.

Tunnels for irrigation measure approximately 30 kilometers, drinking water tunnels about 27 kilometers, road tunnels 25 kilometers, mine tunnels 2 kilometers, and sewage tunnels around half a kilometer.

A 27-kilometer-long tunnel has been constructed to bring water from the Melamchi River in Sindhupalchok to Sundarijal on the northern edge of Kathmandu Valley.

Five years ago, floods in Melamchi caused damage to this tunnel as well.

Earlier this year, a 2.6-kilometer road tunnel was opened to the west of Kathmandu, connecting the Nagdhunga area of Kathmandu with the Sisne Khola region of Dhading district.

According to the Tunneling Association, this tunnel extends from Guhyeshwari near Kathmandu to Tilganga. President Sharma explained this is the first tunnel in Nepal used for sewage and water management.

At the water treatment plant in Guhyeshwari, a copper canal tunnel of approximately 500 meters was constructed to channel excess water directly to Tilganga.

The Kathmandu-Terai Madhesh Expressway is currently seeing the highest volume and length of tunnel construction. The 76-kilometer stretch plans over 10 kilometers of single-lane and a combined 21 kilometers of two-lane tunnel routes.

Similar to Kathmandu’s Nagdhunga tunnel, the 1.1-kilometer-long road tunnel at Siddhababa in Palpa is approaching its final construction phase, according to officials.

Nepal has completed multipurpose irrigation tunnels in two key projects: a 12.2-kilometer tunnel in the Bheri-Babai irrigation project and a 13.1-kilometer tunnel in the Sunkoshi Marin irrigation project.

Association president Sharma states that these and other irrigation schemes feature an aggregate of 30 kilometers of tunnels.

Additionally, approximately two kilometers of tunnels have been constructed for mining operations.

Projects such as the Ganesh Himal copper and tin mines in Dhading also contain nearly two kilometers of tunnel infrastructure, according to Sharma.

Nepal also boasts a unique tunnel museum: located in the Kundule area of Baglung, a 100-foot-long tunnel structure houses the Shaligram Museum dedicated to the preservation of Shaligram stones, which the association refers to as a museum tunnel.

To date, Nepal has not constructed railway tunnels, but experts anticipate tunnels may be built along the East-West Railway once it is completed.

Dr. Basantraj Adhikari, director of Tribhuvan University’s Disaster Study Center in the Institute of Engineering, has stated that Nepal’s tunnel structures are generally very safe from disaster and risk perspectives.

However, he emphasizes that ordinary safety standards and regular precautions may not suffice for exceptional and unforeseen events like the Bhotekoshi flood.

“The government called it a tsunami; I personally consider it a catastrophe of epic scale,” Adhikari said.

“No infrastructure in the world is designed to withstand such a massive disaster. In a country like Nepal with a low economic growth rate, there are various limitations and constraints.”

Vice president of the Nepal Tunneling Association, Kangda Prasai, also described the Bhotekoshi flood as an extraordinary situation.

“Once constructed, tunnel structures are the safest form of infrastructure. However, no tunnel infrastructure had been designed for floods with a probability as low as 0.001 percent. Designing for floods over 150 meters would be financially unfeasible,” said Prasai, a former senior advisor on long-term hydropower projects.

He added that this disaster has taught a vital lesson to clearly define the roles of not only builders but also operators and consultants of hydropower projects.

Director Adhikari explained that extreme climatic activities need to be accounted for in the design of new structures.

“This incident has revealed the need to reconsider design standards and possibly redesign tunnels by incorporating higher risk factors.”

Bhaskar Khatri, president of the Nepal Geological Society, stated that the Bhotekoshi flood highlighted how Nepal is exposed to significant geological risks.

“We reside in a region prone to glaciers, glacial lakes, and earthquakes. Such major accidents can occur,” he said.

“There is a need to adopt new strategies for future infrastructure development.”

As of Thursday, rescue workers continue to search inside tunnel structures for people presumed trapped.

Association president Sharma says that Nepal now possesses skilled local manpower capable of identifying tunnel locations, conducting feasibility studies, and undertaking design and construction; Nepalese workers have built the majority of the country’s tunnels.

Although foreign experts led construction on the Nagdhunga tunnel and Kathmandu-Terai Madhesh Expressway, many Nepalese were actively involved there as well.

“Nepalese professionals have been fully engaged in research, study, design, and construction of hydropower tunnels,” he states.

Sharma explains that due to Nepal’s complex geography, Nepalese engineers have been more involved than foreign engineers in building the majority of tunnels nationwide.

So, why has the rescue operation been unable to reach those trapped inside the tunnels more quickly?

Sharma replies, “The situation has become so complex that the project site no longer has even basic hand tools. Everything has been swept away. There is no equipment available to reach the site, nor operators to run them. The main challenge now is simply transporting even small and large equipment there.”