Māngere Bridge, officially also called the Manukau Harbour Crossing, is a dual motorway bridge over the Manukau Harbour in south-western Auckland, New Zealand, crossing between the suburb also known as Māngere Bridge (southern side) and the suburb of Onehunga (northern side).
The older portion of the bridge, completed in 1983, carries a four-lane motorway with a cycle and pedestrian path suspended under the western side. By 2000, this bridge was carrying 80,000 vehicles daily and had become prone to congestion.
In 2010, a duplication of the 1983 bridge was opened on its eastern side. This doubled the number of general traffic lanes to eight and provided an additional two for buses, for a total capacity of 10 lanes across the harbour. The project had been delayed by disagreements over design and funding, and over the scope of the bridge project and an associated interchange – with the interchange being scaled down after concerns from the local community.
The 1912 walking bridge was replaced with a new walking and cycle bridge in 2022, called Ngā Hau Māngere.
Original bridges
Natural causeway and initial bridge
The location of the initial bridge was originally a naturally formed basalt rock causeway used by Tāmaki Māori, traversable by foot at low tide (except for a shallow tidal stream of a few metres in width). The causeway connected the two halves of the Ngāti Whātua Māngere-Onehunga kāinga complex in the early 19th Century. In 1847, the first ferry service between Onehunga and Māngere was established, where passengers would need to raise a flag on the Māngere shore to signal the ferry operator. In 1858, a large section of the rock walkway was destroyed with dynamite, to allow for more intensive shipping in the harbour.
In 1866, a company was formed to investigate and construct a bridge between Māngere and Onehunga, funded by a grand provided by the provincial government. Civil engineer James Stewart was announced on 7 August 1866 as the winner of a competition for the bridge's design, however stalled due to the Ngāti Mahuta ownership of the land on the southern side of the proposed bridge location restricting what the company could create. These lands had been seized in 1865 under the New Zealand Settlements Act 1863 during the Invasion of the Waikato, however by 1867 the Native Compensation Court split the 485 acre plot between individuals from Ngāti Mahuta, sold some sections to settlers, and kept other sections as crown reserves.
In 1872, tenders for the development of the bridge were proposed. Designed by the Reverend Dr Arthur Guyon Purchas and opened in January 1875, the narrow timber truss bridge featured 20 spans of 12.2 metres supported by jarrah timber piles from Australia, costing £14,997 to build. The jarrah piles soon began to be attacked by Teredo navalis shipworms, and in 1910, more than 30 of the piles had been replaced, as well as the decking. The bridge was also single-lane, and so narrow that pedestrians could barely pass a vehicle safely. It was often unsuitable for pedestrians due to large number of horses and livestock using the bridge, and for residents in the area, the animals often caused noise issues at night, such as when horses would slip on wet surfaces. The bridge was eventually considered structurally unsound and closed in 1914, before being fully demolished.
Old Māngere Bridge
A plan to replace the old wooden bridge was adopted by Māngere ratepayers in May 1911. Designed by R.F. Moore, the designer of Grafton Bridge and Queens Wharf, it was also built by the same company, the Ferro-Concrete Company of Australasia (in a time when almost all bridges in the country were being built by the Public Works Department). The 17-span ferro-concrete bridge was constructed between 1912 and 1916, and at the time was known as the New Mangere Bridge. In late 1913, scoria from Māngere Mountain was used to create a filled wall on the Māngere side of the bridge, while construction of the ferro-concrete structure continued through 1914 and 1915. The ferro-concrete beams and piles of bridge were created using prefabricated concrete, a very unusual method of construction in New Zealand at the time. This ferro-concrete bridge with driven concrete piles was considered a substantial engineering achievement in its time. With a width of 11.6m, it allowed for a double tram track. The bridge however did not provide for enough clearance to let anything but small boats pass under it. A small section of the bridge opened in January 1915, while construction on the full structure continued and dismantling work on the old bridge began. The bridge was officially opened on 31 May 1915 by Prime Minister William Massey, a resident of Māngere.