The Transport Minister says there's a chance the new Northland Expressway project will have a budget blowout. 

The road will go from Warkworth, east of State Highway one, and over the Brynderwyn Hills to the east of the current route, then through Whangarei.  

It's expected to take around 15 years to complete and is one of New Zealand's most expensive infrastructure projects.  

Transport Minister Chris Bishop told Mike Hosking they're doing a lot of preparation work now to make sure there aren't any slip-ups. 

He says they're working on detailed designs, consenting work, and getting the funding model right, but slippages in cost can't be ruled out. 

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