Sydney Harbour Tunnel On 30 August 1992, the Sydney Harbour Tunnel officially opened. The Sydney Harbour Tunnel is a twin-tube road tunnel in Sydney, Australia. The tunnel was completed and opened to traffic to provide a second vehicular crossing of Sydney Harbour to alleviate congestion on the Sydney Harbour Bridge. It is one of two tunnels under the harbour, the … Continue reading On This Day In Australia: In 1992, the Sydney Harbour Tunnel officially opened