The primary radar scans and tracks vehicles as they approach the intersection.
If a vehicle crosses the stop line during a red-light phase, a camera photographs the rear of the vehicle, and a second radar ensures the photograph taken is of the breaching vehicle.
Assistant Commissioner of Road Policing, Dave Cliff, said the cameras would help to improve safety at the selected intersections.
These intersections have a history of red-light crashes, and were chosen following a New Zealand Transport Agency analysis, he said.
"Overseas, red-light cameras have been associated with significant reductions in injury crashes.
"Our goal is to achieve the same at these high-risk intersections, as it is for the road controlling authorities in Auckland and Wellington that have worked in partnership with us on this project."
Mr Cliff said while the cameras were dual-function, as they could also detect anyone who was speeding, they would operate in red-light mode only for the time being.
"The cameras have been operating in trial mode for the last three months to make sure the new technology works perfectly before being switched to enforcement mode," he said.
The cameras were a joint project involving police, Auckland Transport, the New Zealand Transport Agency (including the Auckland Motorway Alliance) and the Wellington City Council.
Ministry of Transport manager of land transport safety Leo Mortimer, said the Ministry of Transport supported the introduction of the new red light cameras in Auckland and Wellington.
"The cameras will provide another useful tool to help prevent fatalities and serious injuries at intersections."
The Transport Agency's road safety director Ernst Zollner, said red light cameras would improve safety for drivers and for pedestrians at these busy intersections.
"These cameras will send a clear message to the small minority of drivers who choose to run red lights that their actions put everyone else at risk, including children crossing on foot."
At this stage the roll-out is limited to the three cameras.
The funding, ownership and operation of any future red-light cameras was yet to be determined.
Ministry of Transport data showed there was 280 fatal and 2,965 serious injury crashes at intersections from 2009 to 2013.
Of those, 12 fatal crashes and 149 serious injury crashes were caused by a driver running a red or an amber light.
Drivers who enter any of the intersections on a red light will be sent an infringement notice with a fine of $150.
Details on new red-light cameras
• Drivers who enter an intersection on a red light will get an infringement notice with a fine of $150.
• Money from the paid fines goes to the Government, not Police.
• The camera uses radars to track and capture vehicles running red lights.
• A primary radar scans and tracks vehicles as they approach intersections
• If a vehicle crosses a stop line during a red-light phase, a camera photographs the back of the vehicle.
• A second radar ensures the photo is of the breaching vehicle.
• The intersections are Karo Drive and Victoria Street in Wellington; Te Irirangi and Ti Rakau drives, Botany; and Lambie Drive Interchange (east-bound off-ramp), Manukau.
