The Nagdhunga Tunnel in Nepal was completed nearly seven years after construction began in 2019. Eight-Japan Engineering Consultants Inc. (EJEC) was involved in the project's planning, surveys, design, and construction supervision. A ceremony marking the completion of Nepal's first road tunnel project was held on July 27, 2026. It was jointly organized by the governments of Nepal and Japan and the Japan International Cooperation Agency (JICA).

The route linking Kathmandu and Naubise, west of the Kathmandu Valley, traverses the Nagdhunga Pass and ranges in elevation from approximately 500 to 1,500 m. The pass has gradients exceeding 10% and a series of sharp curves. Heavy vehicles, including trucks, account for nearly half of all traffic on the route. Congestion is severe and persistent, and serious accidents have occurred along this section in the past. The road is also narrow, with unstable slopes on both the valley and mountain sides, creating a significant risk of landslides and prolonged road closures.

In response to these conditions, JICA conducted a feasibility and data collection study in January 2014. Based on the study, a plan was developed to construct the Nagdhunga Tunnel along this corridor to improve the road alignment, shorten travel times, enhance safety, and promote regional economic development.

EJEC supported the project from route planning and surveys through design and construction supervision.

Construction began in November 2019. Despite numerous challenges—including water inflow and cave-ins during excavation, slope failures caused by heavy rainfall, and setbacks due to the COVID-19 pandemic—the main tunnel breakthrough was achieved in April 2024.

In late September 2024, heavy rainfall caused extensive flooding and landslides in the Kathmandu area, affecting many residents. At the request of local police, the Nagdhunga Tunnel was opened to facilitate evacuations, the passage of emergency vehicles, and the delivery of supplies. It played a vital role in the emergency response, helping more than 4,000 people affected by the disaster. Its use during the disaster was widely reported, including by NHK.

As of September 2026, the tunnel was open to all vehicles free of charge during a trial period, with full-scale operation expected to begin soon.

The ceremony was held near the tunnel's eastern portal (Kathmandu side).
(Photo credits: ① JICA, ②–④ Nippon Koei Co., Ltd.)