NZ Transport Agency road safety director Ernst Zollner said effective speed management was an essential part of creating a safer transport system because speed directly affected both crash probability and crash severity.
In some high-risk situations where other road safety measures could not be applied, speed cameras would be the most effective crash deterrent, he said.
The first new camera will be installed for testing at Ngauranga Gorge in Wellington next week and will go live next month.
Police will use mobile cameras and other enforcement while the camera is being tested.
"While the camera already in use at Ngauranga Gorge is of a newer generation, there have been yet further advances in technology since it was installed last year that we wish to take advantage of," Mr Cliff said.
"It also makes sense that we start the camera upgrade process with the same 'second generation' technology that will ultimately be rolled out across the rest of the country."
Police would reveal the locations for the remaining cameras as soon as they were confirmed and community consultation and engineering assessments carried out.
"Placement of the cameras will be an open process. The site selections are based on robust scientific evidence, and no other reason," Mr Cliff said.
"Police does not receive any money collected from speeding fines, which goes to Government funds."
The cameras would be put in locations assessed as having a high risk for speed related crashes, including those where people have died or been injured in crashes involving speed.
Mr Cliff said about 140 sites around the country had been identified as high risk.
Funding for the speed camera upgrade project is being provided by the New Zealand Transport Agency through its road policing programme, with police and the agency to share ongoing operating costs.
Police will also pilot a small number of newer generation red light cameras before the end of the year.
Location of first 12 new sites for fixed speed cameras
*Indicates existing
State Highway, Ngauranga*
Wainuiomata Road, Wainuiomata
Whitford Brown Avenue, Aotea
State Highway 1, Thorndon*
Wainui Road, Waiwhetu
Hutt Road, Korokoro
Great South Road, Otahuhu*
Mill Road, Totara Park
Murphys Drive, Totara Park
Tamaki Drive, Parnell
Candia Road, Henderson Valley
Great North Road, Kelston*