The Dali's owner and manager have been ordered to pay the US government more than $170m in clean-up costs. Photo: ROBERTO SCHMIDT/AFP
The collapse of a US bridge when a ship hit it sparked a fresh look at the risks the Auckland Harbour Bridge faces, documents reveal.
Six construction workers were killed when a container ship hit a Baltimore bridge in March, spawning a sprawling liability case in America. The ship's owner and manager have already been ordered to pay the US government more than $170m.
The disaster prompted the New Zealand Transport Agency Waka Kotahi to take a look locally.
"Following recent events involving the Baltimore bridge collapse, a risk review has been completed and the Auckland Harbour Bridge risk management plan is being reviewed and strengthened," an update to its board said in June.
The document, released to RNZ under the OIA, went on to say there were two "critical risks" for the bridge that required a "control plan".
It did not say what they were.
"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, Waka Kotahi said in a statement on Wednesday.
It did not detail how the risk management plan had been changed.
The agency told RNZ that the Baltimore strike showed the importance of having a plan to prevent such things occurring and responding effectively if they did.
Acting group manager of transport services Vanessa Browne said ships could only go under the Auckland bridge in daylight on certain tides, there were warning lights, the bridge piers were massive and licensed pilots and tugboats were on hand.
"Currently there is only one cargo ship that passes under the Auckland Harbour Bridge - the Chelsea sugar ship, which travels every six weeks," Browne said.
"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."
Transport Minister Simeon Brown said he was advised that the Ports of Auckland and the harbourmaster had a number of mitigations in place to reduce the risk of any ship striking the Harbour Bridge.
"The NZTA is currently working on options for an additional Waitematā Harbour Connection to strengthen the resilience of this critically important corridor," he said in a statement on Wednesday.
The previous Labour government had announced plans for a tunnel beneath the Waitematā Harbour, but Auckland Mayor Wayne Brown rejected that saying a second bridge would be cheaper.
Auckland's Harbour Bridge. Photo: Tom Kitchin
Top three risks facing NZTA
Aside from the Harbour Bridge, the Transport Agency manages a range of infrastructure, mostly highways.
Its June report said the "resilience" of that infrastructure was the number one risk it faced.
The likelihood of a big problem had gone up in the last three months, it added, estimating there was a higher than 80 percent chance of some part of that infrastructure suffering a "major" impact at least once a year.
"Our critical infrastructure and strategic assets are not resilient to physical threats (eg natural hazards, malicious human-made activity), limiting their ability to fulfil their intended purpose," the report said.
Even after 11 reviews, plans or actions were applied, the residual risk rating remained at, "likelihood - almost certain; consequence - major; rating - critical".
Waka Kotahi's other two top three risks were cyber and information security and climate change.
"The descriptions and ratings given for these risks should not be interpreted as existing problems or situations that require resolution," said Browne.
The descriptions were "of what could potentially occur, if the key controls and actions ... were not in place".
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