Sydney Harbour Bridge
The Sydney Harbour Bridge is a steel through arch bridge across Sydney Harbour that carries rail, vehicular, bicycle, and pedestrian traffic between the Sydney central business district (CBD) and the North Shore. The dramatic view of the bridge, the harbour, and the nearby Sydney Opera House is an iconic image of Sydney, and Australia itself. The bridge is nicknamed "The Coathanger" because of its arch-based design.
The bridge has eight lanes in total, numbered one to eight from west to east. Lanes three, four and five are reversible. One and two always flow north. Six, seven, and eight always flow south. The default is four each way. For the morning rush hour, the lane changes on the bridge also require changes to the Warringah Freeway, with its inner western reversible carriageway directing traffic to the bridge lane numbers three and four southbound.[citation needed]
The bridge has a series of overhead gantries which indicate the direction of flow for each traffic lane. A green arrow pointing down to a traffic lane means the lane is open. A flashing red "X" indicates the lane is closing, but is not yet in use for traffic travelling in the other direction. A static red "X" means the lane is in use for oncoming traffic. This arrangement was introduced in the 1990s, replacing a slow operation where lane markers were manually moved to mark the centre median.[citation needed]