Recently, the TBM (Tunnel Boring Machine) segment production plant for the Tamor Hydropower Diversion Tunnel Project in Nepal, constructed by China Railway No.2 Group under China Railway Group Limited (CREC), officially commenced operation three months ahead of schedule, marking the project’s full transition into its peak construction phase. It is the third TBM-driven water diversion tunnel undertaken by the Urban Transit Engineering Company of China Railway No.2 Group in Nepal since entering the country’s market in 2015, following the successful completion of the Bheri Babai and Sunkoshi Marin projects, both recognized as Nepal’s “National Pride Projects.”
Over the past decade, the Urban Transit Engineering Company of China Railway No.2 Group has progressed from exploring opportunities to establishing a strong presence and achieving sustained development in Nepal. Leveraging its expertise in TBM technology, the company has overcome a wide range of complex geological challenges, continuously set new industry benchmarks, and successfully established the “CREC TBM” brand as a hallmark of excellence in Nepal and across South Asia. Its business portfolio has expanded from government-led infrastructure projects to privately financed energy developments, demonstrating China’s commitment to practical cooperation under the Belt and Road Initiative and contributing to mutually beneficial China–Nepal partnership.
Breaking into the “No-Go Zone” of Tunnel Construction and Establishing Industry Leadership
Nepal is endowed with abundant water resources. However, due to its complex topography and highly challenging geological conditions, inadequate farmland irrigation and electricity shortages have long constrained local development. The Himalayan Siwalik Formation is characterized by highly fractured geological structures, alternating soft and hard rock strata, and severe groundwater infiltration. Once regarded by the international tunneling industry as a “construction no-go zone,” these conditions prevented the implementation of a long-planned inter-basin water diversion project for decades.
In 2015, while aftershocks from Nepal’s devastating April 25 earthquake were still occurring, the construction team of the Urban Transit Engineering Company advanced into the disaster-affected area to launch the Bheri Babai Diversion Tunnel Project. Drawing on its strongest technical resources, the team confronted one of the world’s most challenging geological environments, successfully overcoming numerous engineering obstacles, including severe water inflow, fault zones and squeezing surrounding rock.
In April 2019, the 12.2-kilometer Bheri Babai Tunnel was successfully completed one year ahead of schedule. It became the world’s first project to successfully traverse the Siwalik Formation using TBM technology, fulfilling a decades-long aspiration of the Nepalese people to realize inter-basin water diversion. After being put into operation, the project has provided irrigation for approximately 51,000 hectares of farmland, while its associated hydropower facilities generate annual revenue exceeding US$50 million and benefit more than one million local residents. Nepal’s Prime Minister attended the tunnel breakthrough ceremony in person, praising the achievement as “a miracle in Nepal’s engineering history.” Widely recognized as one of Nepal’s “National Pride Projects,” the successful completion of the Bheri Babai Project not only represented a global breakthrough in applying TBM technology within the Siwalik Formation, but also firmly established China Railway No.2 Group as the industry leader in TBM tunnel construction in Nepal.
Conquering “Hell-Level” Conditions and Repeatedly Setting New Industry Records
Following its initial success, the company earned widespread recognition and embarked on a new stage of development through sustained dedication and engineering excellence.
In 2021, the Urban Transit Engineering Company undertook the Sunkoshi Marin Diversion Tunnel Project, a project of greater scale and significantly higher technical complexity. Stretching 13.3 kilometers, the tunnel passes through the globally rare composite geological formation of the Siwalik Formation and the Kathmandu Nappe, with a maximum overburden depth exceeding 1,320 meters. The project presented what is widely regarded as “hell-level” conditions for TBM construction, involving severe soft-rock deformation, high geothermal temperatures, rock bursts, and repeated risks of TBM entrapment. Confronted with these extraordinary challenges, the project team successfully resolved eight separate TBM entrapment incidents, continuously optimized excavation methods, and overcame major technical obstacles including high-pressure water inrush control, rock burst mitigation, and large deformation control in soft rock. During construction, the team set a world record by completing a 500-meter trial drive within 30 days, and established new world records for a 6-meter-class double-shield TBM with a maximum daily advance of 72.68 meters and a maximum monthly advance of 1,503.3 meters.
In May 2024, the tunnel’s main works were successfully completed approximately one year ahead of the contractual schedule. The project has effectively alleviated drought conditions in central and southern Nepal, while its associated hydropower station is capable of delivering 250 gigawatt-hours of clean electricity annually. Like the Bheri Babai Project, it was designated a “National Pride Project” of Nepal, received six official commendations from the Government of Nepal, and was featured twice by the internationally recognized tunneling journal Tunnel Talk. The project has become a benchmark for infrastructure cooperation between China and Nepal.
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