The Transport Minister is defending the Government's multi-million dollar spend on investigating and adjusting speed limits across the country, saying it costs money to make roads safer.

Answers to written questions to Minister Michael Wood reveal that over the last three years, almost $45 million has been spent on speed management plans, investigating and making changes to speed limits.

The money also helped pay for "extensive stakeholder engagement, [as well as] iwi and community consultation," according to Wood's answer.

It comes at a time when the Opposition has questioned the spending priorities of Waka Kotahi, New Zealand's Transport Agency.

"Labour is trying to slow Kiwis down on the road, and they're spending millions of taxpayer dollars doing it," Act Leader David Seymour said.

"There's now an open question about whether New Zealand's roads have more orange cones or more potholes."

Meanwhile, New Zealand's annual road toll has been on the rise.

Seymour said Waka Kotahi's solution is to spend taxpayer money reducing the speed limits instead of fixing the roads.

But Wood has pushed back.

"It is ridiculous of Act to suggest that Waka Kotahi should not properly resource this area."

He said the Government's target is to reduce the number of people dying or being seriously injured on the roads by 40 percent by 2030.

"Reaching this target requires improving all parts of the transport system – safer roads, safer vehicles, safer drivers and safer speeds."

Despite this, according to Waka Kotahi figures, New Zealand's road toll has been steadily increasing over the past three years.

In 2020, 218 people died in road accidents between January and October. The next year, over the same period it was 229 and so far this year, the road toll is 256.

News of the Government's $45 million spend on adjusting and investigating speed limits comes as National has ramped up its attacks on New Zealand's transport agency.

"Kiwis are sick and tired of all the potholes peppering New Zealand's roads which are damaging vehicles and causing havoc for motorists," said transport spokesman Simeon Brown.  

"We're hearing from people every day who say the roads are the worst they've ever seen them," said transport spokesman Simeon Brown.  

But, again, Wood has pushed back.

He pointed to the $2.8 billion which is being spent to maintain and operate the country's 11,000km of state highways through the 2021-2024 National Land Transport Programme (NLTP).

This, he said, includes an additional $400 million over the initial budget, which is targeted at pavement and surfacing renewals.

"[The Opposition's] suggestion of a choice between good speed management and maintenance is also absurd and immature; we need to do both."