Nicola Willis says 'important questions to be asked and answered' after Interislander upgrade cost blow-out

"Important questions" need to be asked and answered as to how the Cook Strait ferry upgrade project has "blown out at regular intervals", Finance Minister Nicola Willis says. 

The Government on Wednesday revealed it would not contribute significant new funding to KiwiRail - which runs the Interislander ferry service - to address rising costs involved in upgrading the fleet and terminal infrastructure. 

It had quadrupled in cost since 2018 to about $3 billion overall - much greater than the original $775 million business case. 

Speaking to AM on Thursday, Willis reiterated her frustration. 

"I'd much rather this problem never landed on my desk," she told host Ryan Bridge. "I'd much rather we had a simple, value-for-money solution and the ferries were just going to be delivered on time, on budget." 

Willis said, however, it was important New Zealanders have "reliable, safe ferry services... in a way that provides good value-for-money". 

She suggested the project "wildly diverged from what it was meant to be at the beginning". 

However, Willis still had confidence in KiwiRail. 

"KiwiRail, by their own admission, are not marine engineers, they're not port experts, they're not experts at building wharves - so I want to make sure we have the right people involved [on the project]," she said. 

"I also have to acknowledge that KiwiRail isn't always going to be best placed to work out what's best for taxpayers, for ferry passengers, for freight passengers - they're going to be the best people to work out what's best for KiwiRail's passengers and freight but we need to take a look at the bigger picture, and work with all of the people involved here. 

"My first step is to experts around the table; experts at developing infrastructure on time and on budget, experts on transport projects, experts who will help me ensure that I don't fall into the same money trap that the last Government did, where a project was allowed to quadruple in cost and the cheques just had to keep on being written." 

Meanwhile, KiwiRail chief executive Peter Reidy has defended his team's work and processes - despite the Government announcing it would scrap the upgrade. 

Reidy said the engineering project was "exceptionally complex". 

"We're talking about a seismic area of New Zealand; we're talking about having to lift the whole Wellington infrastructure a metre because of the flood modelling codes," he told AM. 

"Once you start to look through all the design and the real costs of constructing, that's where the envelope obviously started to increase." 

Four unions representing maritime and rail workers were outraged at the Government's decision. The decision showed a lack of understanding of how important the connection is for the supply chain, the Maritime Union said. 

But Willis said other options had to be looked at. 

"For me, this is about finding a way forward."