The Auckland Harbour Bridge, opened on 30^th May, 1959, is a steel truss bridge that carries eight lanes of traffic over the busy waters of Waitemata Harbour, joining St Marys Bay in Auckland with Northcote in the former North Shore City, New Zealand. Being one of the most critical bridges of New Zealand, regular maintenance has kept the Auckland Harbour Bridge in good condition for the 165,000 cars that cross it daily.  The bridge construction took nearly four years, Dorman Long and the Cleveland Bridge & Engineering Company being the contractors. The large steel girder sections were partially pre-assembled then floated into place on construction barges.

The 1.2 Km long structure is actually made up of three sections. The section in the middle is the original four-lane 'truss' bridge that was built over four years by a team of 1000 men at an approximate cost of £7,516,000. It was opened with tremendous excitement on 30 May 1959. Within one year 4.9 million vehicles had crossed the bridge and by 1965 traffic rose to 9.3 million.

This rapid growth in traffic necessitated the decision to extend the bridge from four lanes to eight lanes to increase its capacity and ease congestion. This was done by adding two box girder bridges to each side of the bridge. Designed and manufactured in Japan they instantly became known as the 'Nippon clip-ons' and were opened to traffic on 23 September 1969.

The Auckland Harbour Bridge is also known as one of the best maintained bridges in the world. From day one comprehensive maintenance has been carried out and over the years there have been a number of major upgrades including seismic, wind loading and fatigue crack upgrades.  Now, nearly 50 years since the Auckland Harbour Bridge was first opened Transit is preparing to upgrade the strength of the bridge once more to cope with the increasing number of vehicles, especially heavy trucks, using it. Bridge Strengthening Preparation works for the upgrade started in April 2008, and the main strengthening works started in August under the supervision and administration of New Zealand Transport Authority. This involves strengthening the box

Strengthening Benefits

• The ongoing maintenance and monitoring NZTA carries out on the bridge means that the clip-ons are stronger than ever.
• The daily average number of cars crossing the Auckland Harbour Bridge is presently around 165,000, with more than 200,000 vehicle crossings recorded some days.
• Current improvements to the Auckland Harbour Bridge clip-ons (box girders) will ensure they stay in good condition for the next 30 to 40 years.

Bridge Features

• One of the most strategically important bridges in New Zealand.
• One of the best maintained bridges in the world.
• The 50 year old bridge is no stranger to upgrades and facelifts.
• In the last eight years alone, NZTA has undertaken annual, six and three month inspections together with daily monitoring, painting and other maintenance.
• The current improvements involve fixing hundreds of tonnes of steel to the inside and outside of the box girders by welding and bolting.
• Strengthening commenced in August 2008 on the northbound box girder.
• Initial strengthening was completed in July 2008. Works switched predominantly to the southbound clip-on on 2 August 2009.
• Strengthening of the southbound clip-on was completed in December 2010 and truck restrictions lifted.