Auckland Harbour Bridge

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The Auckland Harbour Bridge is an eight-lane road bridge over the Waitemata Harbour, joining Freemans Bay in Auckland City with Northcote in North Shore City, New Zealand. It spans a total distance of 1.15 km with a main span of 243.8 m, rising 43.27 m above high water.

Prior to construction of the bridge, the quickest way of getting from Auckland to the North Shore was via one of the regular passenger or vehicular ferries. By road, the shortest route was through West Auckland via Riverhead and Albany, a distance of over 40 kilometres.

Severe traffic congestion at peak time remains a major issue (and has led to the bridge sometimes being referred to as "The Car Strangled Spanner" in a parody of the national anthem of the United States of America).

1 Construction
2 The 'Nippon clip-ons'
3 Traffic Management
4 Future plans
5 References
6 External links

[edit] Construction

Support structure of Auckland Harbour Bridge

The bridge took four years to build and was opened on May 30, 1959 by Prime Minister Sidney Holland, with four lanes of traffic, two in each direction. Four men were killed during construction, and their names are recorded on a memorial plaque underneath the bridge at the Northcote end.

The bridge started out as a toll bridge, with toll booths located at the northern end. The government discontinued tolling on March 30, 1984, and the booths were removed ^[1]

[edit] 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. The bridge was originally to have eight lanes of traffic but the government thought that other New Zealand cities might get jealous^{[citation needed]}, so they built it with four lanes, but it was soon found that four lanes were not enough.

In 1969 two-lane box girder clip-on sections were added to each side, doubling the number of lanes from four to eight. The sections were manufactured by Japanese contractors (Ishikawajima-Harima Heavy Industries Ltd), which led to the nickname 'Nippon clip-ons'. They have an expected lifetime of 50 years and will thus need to be replaced by 2016.

[edit] Traffic Management

A "tidal flow" system was implemented whereby the traffic direction of two of the centre lanes is changed in order to provide an additional lane for peak period traffic. During the morning rush, five of the eight lanes are allocated to southbound traffic heading towards Auckland. This situation is reversed in the afternoon, when five lanes are allocated to northbound traffic. At all other times of the day the lanes are split evenly.

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. A specially designed barrier machine moves the barrier by one lane four times a day, at a speed of 6 km/h. It takes 40 minutes to move the entire barrier.

[edit] Future plans

Even with the clip-on section and the traffic management in place, the Harbour Bridge is experiencing severe congestion during rush hours, which will only get worse as North Shore City grows and Auckland City becomes more densely settled. Therefore, there is growing pressure for another harbour crossing.

Several solutions have been proposed, including building another bridge alongside the existing one, a tunnel, or combinations of both. Following a detailed scoping study undertaken in 1996, Transit New Zealand identified its preferred options for a new crossing - either a new bridge approximately 500 m west of the bridge connecting to the North-Western Motorway (SH16) via a tunnel underneath Ponsonby and Grey Lynn, or a tunnel slightly to the east of the bridge connecting to the Central Motorway Junction via twin cut-and-cover tunnels under the western CBD / Victoria Park.

These options are by no means final, as the immense costs and political implications (due to the effect of the related road construction on residential areas) have so far stalled any further action on this project. Several projects either side of the bridge are underway or planned to ensure that the motorway capacity on both sides matches that of the peak time capacity of the bridge, and to enhance the attractiveness of public transport. These include the upgrade to the Central Motorway Junction, the Harbour Bridge to City tunnel (which will increase capacity between the Central Motorway Junction and the bridge by 50%) and the Northern Busway (which will provide a bypass parallel to the Northern motorway as it approaches the bridge). The future timing of an additional harbour crossing may also be delayed by the completion of the Western Ring Road (a combination of upgraded and new motorway skirting the western edge of the harbour and suburbs), which will provide some relief for traffic travelling between the North Shore and West Auckland. This route is expected to be completed by 2020 at the latest.

At the moment, the official political line is that a second harbour crossing is to be delayed:

The (Auckland City) Council will work with Transit New Zealand, the ARC, and the North Shore City Council to develop and implement measures, designed to optimise the future use of the existing Harbour Bridge and its approaches, for the peak period movement of people. This is to avoid or substantially delay the need to construct a second crossing of the Waitemata Harbour. ^[2]