The longest tunnel in Southeast Asia, and one of the biggest and the most modern tunnels in the world is the Hai Van Pass tunnel.
It was built through the Hai Van Pass with a length of 12 km. Of this, the main tunnel is 6 km long in total. The tunnel starts from Lang Co of Phu Loc District of Thua Thien Hue Province to Hoa Hiep Ward, Lien Chieu District of Danang City.
The Hai Van Pass is now a tourist attraction. Opened to traffic in early 2005, the tunnel has helped reduce traffic accidents, save fuel and increase transportation efficiency. Only cars, trucks, buses and motorcycles of at least 175 cc are allowed to go through the tunnel.