The Hai Van Tunnel is one of Vietnam's largest and most technically demanding underground transport projects. Comprising two main sections, Hai Van 1 and Hai Van 2, it connects Danang with the southern part of Hue City.
The project is also a prominent example of Japan's official development assistance (ODA) being used to develop Vietnam's transport infrastructure.
According to Deo Ca Traffic Infrastructure Investment Joint Stock Company, construction of Hai Van 1 began in 2000, with total investment exceeding USD 250 million, financed mainly through Japanese ODA loans.
After nearly five years of construction, the tunnel officially opened to traffic on June 5, 2005. Stretching 6.28km, it was the longest road tunnel in Southeast Asia.
In 2016, a second tunnel, Hai Van 2, was designed to run parallel to the original. It officially opened in January 2021.
Le Chau Thang, deputy general director of Deo Ca Traffic Infrastructure Investment Joint Stock Company, said the benefits of the tunnel had become evident since it entered service.
Previously, crossing Hai Van Pass took 45-60 minutes. The tunnel has reduced the journey to just 10-15 minutes, lowering transport costs and improving connectivity between Danang and Hue, as well as with other parts of the country.
The tunnel has also helped reduce the risk of road accidents while facilitating freight transport and tourism.
Each tunnel has two traffic lanes, with emergency stopping bays provided along certain sections to accommodate vehicles travelling through the route.
The maximum permitted vehicle height is 7.5 metres, while the speed limit is 70km/h. These technical specifications are designed to ensure safety and the efficient operation of this key transport corridor.
Emergency exits connect Hai Van 1 and Hai Van 2, allowing for evacuation and emergency response in the event of an incident.
Regular inspections and maintenance are carried out to maintain operating conditions and ensure the safety of motorists.
Thang said improved transport conditions had led to a steady increase in traffic volumes. More than 3.9 million vehicle trips passed through the tunnels in 2025, while the figure had already exceeded 3.5 million in the first nine months of 2026.
"Easier transport has also stimulated the regional economy, strengthened security and created greater opportunities for investment and tourism," he said.
Tunnel operations run around the clock, seven days a week, with 281 managers, engineers and workers organised into rotating shifts, Thang added.
Each shift has an on-site command team ready to coordinate personnel and equipment and respond to emergencies.
"In 21 years of operation, the Hai Van road tunnel has not experienced any major accident that required it to be closed for several days. This reflects effective management and operations, with safety regulations fully observed and serious incidents avoided," he said.
In June 2025, Mori Takero, Japan's consul general in Danang, visited the engineers and management team responsible for operating the Hai Van road tunnel.