The Cross-Harbour Tunnel (abbr. CHT or XHT; (or informally 紅磡海底隧道, 紅隧) is the first tunnel in Hong Kong built under water. Since its construction, its traffic has increased, becoming one of the most congested roads (mainly towards Hong Kong Island direction) in Hong Kong and the world.
The 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), Hong Kong Island 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.
It was administered by The Cross-Harbour Tunnel Company Ltd until August 1999, when the operation franchise agreement expired and the government assumed control.
Although other road tunnels, the Eastern Harbour Crossing and Western Harbour Crossing, have been built across the Victoria Harbour to divert traffic from the Cross-Harbour Tunnel, traffic congestion has not improved. Two reasons include the less convenient locations of the other two tunnels compared with the Cross-Harbour Tunnel, and more importantly the control of new tunnels by the powerful state-owned investment group CITIC Pacific. The tolls for crossing each of the other two tunnels are significantly higher, and were further increased in 2005 by up to 67% to boost investment returns.
The Government of Hong Kong claimed it was powerless to prevent the sharp increase in tolls, and is currently looking at other options to relieve the traffic, including a plan to build a fourth harbour crossing tunnel. Although it encourages motorists to use public buses (which are usually 90% full) but does not give buses priority access to the tunnel and strongly encourages taking MTR East Rail Line and then switching to MTR Tsuen Wan Line at East Tsim Sha Tsui Station.