Following the collapse of a major bridge in Baltimore last week, NZTA national manager maintenance and operations Andrew Clark explains the resilience of the Auckland Harbour Bridge.
The Auckland Harbour Bridge is the most important single transport connection in New Zealand and one of the most travelled routesin the country.
In addition to 170,000 vehicle crossings and 35,000 bus passengers daily, the bridge carries two watermains, a high voltage power line, a gas pipe and numerous communication cables.
By 2051, 240 million kilometres of truck movements, two billion kilometres of light vehicle movements and 11 per cent of all public transport trips across the Auckland region will rely on this crossing corridor.
The tragic event in Baltimore last week highlights the importance of having a plan in place to prevent incidents like ship strikes from occurring and - in the low likelihood they do occur - to be able to respond to them quickly and effectively.
The risk of a ship strike to the Auckland Harbour Bridge has been assessed as having a rare likelihood due to the amount of risk mitigations that are currently in place.
The Ports of Auckland and Auckland Transport, through the harbourmaster, have processes in place to mitigate the risk of large ships striking the Auckland Harbour Bridge. These include having a licensed Ports of Auckland pilot on board the ship, with tugboats to guide the ship should it lose power or steerage.
Ships are also restricted to moving under the bridge on certain tides and only during daylight hours. For extra guidance, there are also GPS identifiers placed on the bridge’s piers.
Lights on either side of the bridge are in place to alert vessels of hazards, there is a beacon (light) on the top of the bridge for aviation and there are channel markers with beacons to indicate to vessels where the channel is.
The cargo ship Dali is stuck under part of the structure of the Francis Scott Key Bridge after the ship hit the bridge in Baltimore last month. Photo / AP
Regular safety inspections and emergency response plans are also in place and tested and maintained with other agencies and local authorities.
Currently, only one cargo ship passes under the Auckland Harbour Bridge - the Chelsea sugar ship, which travels every six weeks. This vessel is much smaller than the container ship that struck the Key Bridge in Baltimore and is therefore much less likely to cause such extensive damage.
The bridge piers built in the 1950s are massive concrete box-like structures founded on rock beneath the sea bed. We ensure these are regularly inspected, maintained and upgraded when needed to preserve the integrity of the structures.
NZTA national manager maintenance and operations Andrew Clark.
With Auckland’s population set to hit two million by the end of the decade, we know that an additional harbour connection is a must-have. While the current bridge is in good condition, it is ageing and vulnerable to closures caused by traffic incidents and adverse weather events.
That’s why NZ Transport Agency Waka Kotahi (NZTA) is in the final stages of an indicative business case for improving resilience and connectivity across the harbour as part of the Waitematā Harbour Connections project.
While this project will provide much needed resilience for the city’s transport network, it also presents an opportunity to build a more efficient transport system that supports urban development and intensification and supports the future of the city’s economy.
Waitematā Harbour Connections is a significant long-term investment in the resilience and efficiency of our land transport system. It will shape the future of the city and has the potential to deliver an impact the whole country will benefit from - ending our reliance on a safe but single connection.
