Kai Tak Tunnel

Entrance to Airport Tunnel in Kowloon Bay, taken from the window of a bus

Kai Tak Tunnel (Traditional Chinese: 啟德隧�"), formerly known as the Airport Tunnel (機場隧�") is a tunnel in New Kowloon, Hong Kong, which connects the Kowloon Bay and To Kwa Wan areas by going beneath the former Hong Kong International Airport (Kai Tak Airport). It provides a quick link between the two ends of the tunnel, as before the construction of the tunnel vehicles have to detour through Kowloon City to reach the other end.

Construction of the tunnel started in 1976, but because of the difficulties in digging under the airport runway, it was not complete until 1982. It was known as Kowloon Bay Tunnel (九龍灣隧�") at the time of its opening, and it was also the first tunnel in Hong Kong to be toll-free.

The tunnel consists of a pair of tubes of about 7m 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 can branch off onto Song Wong Toi Road. It is the only major vehicular tunnels in Hong Kong built by the cut-and-cover technique.

Many major express bus routes of Kowloon Motor Bus between Kowloon and the eastern end of New Kowloon travel through the Airport Tunnel. Most of them run between the Kwun Tong District and Tsim Sha Tsui. They include 11X, 28, 98D, 98P, 215X, 219P, 219X, 296D.

As of 2001, an estimated 60000 vehicles use the tunnel each day.

The Hong Kong Government has announced on March 2, 2006 that the tunnel will be gazetted on March 3, 2006 to be renamed as Kai Tak Tunnel, effective from May 4, 2006, after several years of consultation, including the Kowloon City District Council.