Auckland Harbour Bridge
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AucklandHarbourBridge.jpg
Auckland Harbour Bridge is an eight lane road bridge that spans the Waitemata Harbour joining Freeman's Bay in Auckland City with Northcote in North Shore City, New Zealand
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History
Prior to construction of the bridge, the quickest way of getting from Auckland City to the North Shore was via one of the regular passenger ferries. By road, the only route was through west Auckland, a distance of some 20 kilometres.
Construction
The bridge took four years to build and was opened on 30 May 1959 by the then Prime Minister Sidney Holland. It originally had four lanes of traffic, two in each direction. The bridge spans a total distance of 1.15 km with a main span of 243.8 m and rises 43.27 m above the high tide level. Four men were killed during construction of the bridge, their names are recorded on a memorial plaque located underneath the bridge at the Northcote end.
The Nippon clip-ons
Owing to the rapid expansion of suburbs on the North Shore and increasing traffic levels it was necessary to increase the capacity of the bridge. Only ten years later in 1969, two-lane box girder clip on sections were added to each side, doubling the number of lanes from four to eight. These sections were manufactured by Japanese contractors, Ishikawajima-Harima Heavy Industries Ltd, which led to the nickname 'The Nippon clip-ons'.
Traffic Management
A "tidal flow" system was implemented whereby the traffic direction of one of the center lanes was changed in order to provide an additional lane for peak period traffic. Thus during the morning rush, 5 of the 8 lanes are allocated to southbound traffic heading towards Auckland city centre. This situation is reversed in the afternoon when 5 lanes are allocated to northbound traffic. For many years lane directions were indicated by overhead signals.
In the late 1980s a number of fatal head-on accidents occurred when vehicles crossed lane markings into the path of oncoming traffic. In 1990, a movable concrete safety barrier was put in place to separate traffic heading in opposite directions and eliminate head-on accidents. Specially designed barrier machines move the barrier by one lane 4 times a day at a speed of 6 km/h. It takes 40 minutes to move the entire barrier.
Traffic congestion issues at peak times have led to the bridge being referred to as "The Car Strangled Spanner" in a parody of the national anthem of the United States of America.
Future plans
The clip-on sections have a lifetime of fifty years and will need to be replaced by 2016. Before the clip-on sections are replaced, another harbour crossing will have to be constructed to cope with the ever increasing volume of traffic that uses the bridge every day. Several solutions have been proposed, including another bridge built alongside the existing bridge or a tunnel under the Waitemata Harbour. As of 2004, no final decision has been made.