The answer is in the question - Sydney Harbour - a harbour not a lake
To enable people to cross the harbour in a vehicle or on foot.
It helped Sydney expand allowing people to cross easily from south Sydney to North Sydney.
1 car cross the Sydney Harbour bridge in one century
Sydney Harbour Bridge crosses Port Jackson.
Figures in 2001 showed that almost 160 000 vehicles use the Sydney Harbour Bridge every day. This is despite the fact that the Sydney Harbour tunnel was built in 1992. It also doesn't take into account the number of trains that cross the bridge on the two railway lines each day.
The Sydney Harbour Bridge changed the transportation of Sydney by allowing more rapid access between the North Shore and the central business district, which previously relied on ferries, or motorists had to travel the long way around. Rail, vehicular, bicycle and pedestrian traffic now cross the bridge.
It was built to cross the Waitemata Harbour.
About 160 000.
It was built to connect the central business district of Sydney with the populated areas on the North Shore of Sydney and create a direct route across the harbor. Ferries also cross the waters of Port Jackson.To speed up travel from one side of the Harbour to the other. It would have been horrible having to get your loads all the way around it all the time, it isn't the smallest thing.It was built to let people cross to the other side rather than driving right around to get to the other side
Arch bridges are one of the world's most ancient bridge forms. The arch gives the bridge its essential strength. Between the engineer of the Sydney Harbour bridge, Ralph Freeman, and the designer, JCC Bradfield, this was seen as the best option for the purpose. Freeman felt that since the purpose of the bridge was to cross a wide harbour which often saw some fairly wild weather, the arch shape would be the most stable. Originally, the bridge's designer, JCC Bradfield, proposed a suspension bridge, then a cantilever bridge, which was the first proposal accepted. After that, Bradfield turned his sights towards an arch bridge, after travelling overseas and seeing the developments in light steel which made a steel arch bridge such a possibility.