Skip to content

Access keys for

  • h Home
  • m Menu
  • 0 Show list of access keys
  • 2 Skip to content
  • 3 Skip to top

Auckland Harbour Bridge box girder strengthening project

Project overview

Project introduction

As one of New Zealand’s critical transport links, ongoing maintenance keeps the Auckland Harbour Bridge in good condition for the 165,000 cars that cross it daily.

  • Estimated project cost

    $20 million to $100 million
  • Project type

    Road maintenance
  • Project status



A recent project has seen the box girders, also known as the clip-ons, strengthened to their maximum capacity. Approximately 900 tonnes of steel has been bolted and welded onto the clip-ons to extend the life of the bridge.


  • The ongoing maintenance and monitoring NZ Transport Agency 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.
  • One of the most strategically important bridges in New Zealand, the Auckland Harbour Bridge is also 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, NZ Transport Agency has undertaken annual, six and three month inspections together with daily monitoring, painting and other maintenance.
  • The current improvements involves 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.