While the Sydney Harbour Bridge is a steel through arch bridge, the Sydney Harbour Tunnel is what?
Sydney Harbour Tunnel The Sydney Harbour Tunnel is a twin-tube road tunnel in Sydney, Australia. The tunnel was completed and opened to traffic in August 1992 to provide a second vehicular crossing of Sydney Harbour to alleviate congestion on the Sydney Harbour Bridge. It is the only tunnel under the harbour, although there are plans to build a set of rail tunnels.
Cross City Tunnel The Cross City Tunnel is a 2.1 km-long twin-tunnel tollway located in Sydney, New South Wales, Australia, which is operated by Transurban. It links Darling Harbour on the Western fringe of the central business district to Rushcutters Bay in the Eastern Suburbs. The tunnel is actually two distinct tunnels and they largely follow a route underneath William Street and Park or Bathurst Streets, depending on whether it is eastbound or westbound.