The briefing says the expansion of safety cameras, including point to point cameras, will require a new infringement processing system.
Genter confirmed earlier this year that the Government was considering introducing the cameras, which take a snap of a vehicle at the beginning and end of a stretch of road and calculates the average speed, to beat motorists who slow down for speed cameras.
Nash said he had been advised that the system continued to cope but would need replacing at some stage.
"I rely on Police to maintain the integrity of the system from within baselines for now."
Police would not say what its contingency plan was in the event the infringement system, which processes all traffic tickets issued by police, stopped working.
It also would not say how many infringements were being processed at present.
But figures in the briefing show that in 2017/18, police issued close to 700,000 notices from speed and red light cameras alone.
Police National Road Policing Manager Superintendent Steve Greally said Police, the Ministry of Transport, and NZTA were currently considering options for a replacement.
That work was being carried out alongside the work on point to point camera trials, he said.
Greally also confirmed the NZTA had installed point to point cameras at the site of a future trial in Auckland but they were not operating in enforcement mode.
"An announcement on the location of average speed camera trial areas and the timing of the trials is expected to be made next month.
"No enforcement activity will be undertaken and no infringement notices will be issued prior to the commencement of these trials, and the locations of the trial sites will be well publicised, well in advance of any enforcement activity," he said.
The Government is also looking at ways to increase the number of traffic cameras, the briefing said.
The current numbers are 48 static speed cameras, 43 mobile speed cameras and three red light cameras.
Auckland Transport (AT) also operates red light cameras at six sites and is working on a further six.
Auckland Mayor Phil Goff has previously said 42 cameras will be added over 10 years.