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Auckland Harbour BridgeAuckland 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 in New Zealand. The bridge took four years to build before being opened on 30 May 1959 by the then Prime Minister Sidney Holland. 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. Prior to the construction of the bridge, the quickest route between Auckland City and the North Shore was by the regular passenger ferry service. By road, the quickest route was through west Auckland, a distance of 20 km. Once completed, the bridge contributed to the rapid expansion of suburbs on the North Shore, with a large number of people moving to 'The Shore' and commuting into Auckland City each day. In 1969, two-lane box girder clip on sections were added to each side, thereby 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 'Nippon clip-on'. A "tidal flow" system was implemented where the traffic direction of one of the center lanes was reversed during morning peak traffic flow and another center lane was reversed for the afternoon peak. Thus during the morning rush, 5 of the 8 lanes are allocated to southbound traffic going towards the city centre. The 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 through vehicles crossing lane markings into opposing traffic. In 1990, a movable chain of hinged concrete barriers was put in place to separate traffic heading in opposite directions and eliminate head-on accidents. Specially designed transfer vehicles move the barrier by one lane 4 times a day at a speed of 3 km/h. It takes 40 minutes to cover the length of the barrier. The clip-on sections only have a life time of fifty years, so they will have to be replaced by 2016. Before the clip-on sections are replaced, another harbour crossing will have to be constructed to cope with the traffic. Several solutions have been proposed, including another bridge built next to the current bridge or building a harbour tunnel. As of 2004, no final decision has been made.
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