Probably unknown to many residents unless commuters by road to the Kowloon Bay districts and beyond is the tunnel under Kai Tak Airport. Construction of the tunnel had started by 1975, but because of the difficulties in digging under the airport runway, it was not complete until 1982. The southern tube opened to two-way traffic on 29 June 1982. The second (northern) tube opened on 8 October that year. The Airport Tunnel was the first tunnel in Hong Kong to be toll-free.
With the airport's shutdown in 1998, the Airport Tunnel no longer fulfilled to its name. The Hong Kong Government announced renaming it Kai Tak Tunnel, effective from 4 May 2006.
The tunnel consists of a pair of tubes of about 7 metres diameter each, 1.26 km long. The southern tube carries west-bound traffic from Kowloon Bay to Ma Tau Kok. A point of interest is that the eastbound tunnel branches off onto Sung Wong Toi Road. It was the only major public vehicular tunnel in Hong Kong built entirely by the open cut-and-cover technique.