The Cross-Harbour Tunnel is the first tunnel in Hong Kong built underwater. It consists of two steel road tunnels each with two lanes constructed using the single shell immersed tube method.It is the earliest of three vehicular harbour crossings in Hong Kong, opened for traffic on 2 August 1972. It was constructed under 30-year private-sector franchise based on a build–operate–transfer model, and title passed to the Hong Kong government in August 1999 upon termination of the franchise. It has become one of the most congested roads in Hong Kong and the world, with 116,753 daily vehicles in 2013.HistoryConstructed by a private company and operated under a 30-year franchise, the 1.8 km long tunnel crossing opened in 1972, providing the first road link between Kowloon and Hong Kong Island. Prior to the opening of the tunnel, cross-harbour vehicular traffic depended on ferries and for passengers, the Star Ferry. The project was joint-engineered by Scott Wilson Kirkpatrick & Partners and Freeman Fox & PartnersThe tunnel links the main financial and commercial districts on both sides of Victoria Harbour, connecting Kellett Island (a former island now connected to Hong Kong Island by reclamation), with a reclaimed site at Hung Hom Bay, Kowloon. The toll plaza is located at the Hung Hom end of the tunnel, and has 14 toll booths.