Auckland Harbour Bridge (New Zealand)
|Auckland Harbour Bridge|
|Location Map ( geo)|
|New Zealand Transport Agency|
Error: New Zealand Transport Agency is not a highway authority
|SH1 (New Zealand)|
|Crossings related to the SH1 (New Zealand)|
Auckland Harbour Bridge is by far the largest and best known bridge in New Zealand. It spans the Auckland Harbour immediately to the north of the CBD area, connecting the sprawling northern suburbs to the city centre. The bridge was built in the late 1950s, opening in 1959 and replaced a very busy ferry service below. Such was the success of the bridge that it was widened in 1969, and there have been talks regarding a second harbour bridge almost ever since.
The original bridge comprises a massive steel arch truss which is supported on a series of concrete piers. Elevated sections of highway form the approaches at either end, with the truss spanning the open water channel. In order to provide sufficient clearance for shipping, the truss starts below the road deck, before climbing up to form an arch above the deck over the widest span. The deck in the centre is then supported by a series of hangers. The whole design leads to a very lightweight appearance, with the approaching viaducts in particular formed from slender columns under the deck.
The bridge as first built was never wide enough for the traffic volumes it needed to carry, so less than a decade after opening work started on widening it. This took the form of two massive steel tubes or girders cantilevered off of the existing concrete piers on large 'ears'. The extension doubled the bridges capacity, creating two two lane carriageways in each direction. At either end, the elevated approaches were supported on much more substantial looking concrete piers due to the different nature of the structure.
The bridge now carries 8 lanes of traffic, although for many years this has incorporated a tidal flow facility. Previously adjusted manually, the central barrier is now moved by a travelling machine, and can be moved several times a day if necessary. It allows traffic lanes to be adjusted from the 'normal' 4+4 to 3+5 in either direction, obviously the extra lanes being available to city bound traffic in the morning peak and northbound in the afternoons.