Sydney Harbour Bridge and opened in 1932. The bridge's design was influenced by the Hell Gate Bridge in New York City. It is the sixth longest spanning-arch bridge in the world and the tallest steel arch bridge, measuring from top to water level. It was also the world's widest long-span bridge, at wide, until construction of the new Port Mann Bridge in Vancouver was completed in 2012. The Sydney Harbour Bridge was added to the Australian National Heritage List on 19 March 2007 and to the New South Wales State Heritage Register on 25 June 1999. The southern end of the bridge is
Sydney Harbour Tunnel to Sydney Harbour. A trench was dredged before the arrival of the IMTs and then the IMTs were lowered into the trench by a system of pontoons and control towers. After the IMTs were in place the trenches were backfilled and then a rock armour was placed over the top to protect the units against marine hazards, such as anchors or sinking vessels. The land tunnels were constructed by a combination of driving and cut-and-cover techniques, designed to be strong enough to withstand the impact of earthquakes. The northern end pylons of the Sydney Harbour Bridge were altered to allow