All images collected would be deleted after 48 hours, except for a "small number of anonymised images" kept for reporting purposes, Waka Kotahi said.
The Automobile Association's (AA) road safety spokesperson Dylan Thomsen said statistics indicated a driver was around four times more likely to be involved in a crash when using a phone and distracted.
"These cameras, assuming that the trial proves that they work really well, are a tool that we think could be used to help enforce and get people to make sure they're doing the right thing without having to have officers' time used up."
Yesterday, AA's general manager of motoring affairs Simon Douglas said the association was "very supportive" of the trial.
"Phones have become such an important part of our daily lives that we find it difficult to almost function without them.
"It's almost not that phones have become a part of driving, it's that driving is interrupting our continual linkage to the world through our phones and it's a habit we just need to break because when it comes to driving you need to be 100 per cent focused."
Waka Kotahi would not disclose the locations being used in the trial as motorists may behave differently if they know where the cameras are.
In a tweet, the agency said it had worked with the Office of the Privacy Commissioner to "address all privacy matters".
Waka Kotahi director of land transport Kane Patena said if a picture of a driver was taken and there was no evidence of distraction, the image was automatically deleted after 15 minutes.
He said the aim of the trial was to understand the scale of the problem of distracted drivers and then determine what the next step should be to tackle it.
"We know that it contributes to a significant proportion of deaths and serious injuries on our road."
In 2020, there were 24 fatal crashes and 111 serious injuries where distraction was identified as a contributing factor, Patena said.
The results of the trial – which the agency said was the first of its kind in New Zealand - would be published in a report after the trial had been completed.
According to Waka Kotahi, on average, one person is killed every day on New Zealand roads and another seven are seriously injured.
