National promises billions on 10 'significant' roads

National will spend another $10.5 billion improving the next generation of Roads of National Significance, the party's transport spokesman Simon Bridges says.

Like the $12 billion already spent on seven significant roads, Mr Bridges said the next tranche of roads would come from the National Land Transport Fund and public-private partnerships.

"Our country is growing and we are committed to building world-class infrastructure to encourage that growth to continue," he said.

Mr Bridges said the first seven projects, which were finished or under way, had improved travel times.

"The completed Roads of National Significance are also our safest, with no road fatalities to date."

ACT leader David Seymour questioned National's ability to deliver on the projects in partnership with New Zealand First.

"The Northland four-lane motorway won't go ahead with Winston Peters in a National government because he won't allow public-private partnerships to fund it," he said.

He said ACT could ensure the projects went ahead.

Labour's transport spokesman Michael Wood called the announcement a "gambit based on the latest polls" and criticised the lack of a cost-benefit analysis.