Drivers who slow down for cameras in danger of being caught out by high average speed.
Cutting edge speed cameras that can catch out drivers who slow down for traditional cameras then speed up again are being considered by police.
The cameras will judge how fast drivers are travelling between two points. If adopted, they measure the time it takes for vehicles to travel between them to calculate average speed.
It would mean drivers who slow down on spotting speed cameras, only to rev up again once they've passed, would be caught at the second hurdle.
That was indicated to a conference in Auckland yesterday by Assistant Police Commissioner Dave Cliff, who is responsible for road policing.
Mr Cliff told the Traffic Institute of local authority engineers and consultants that police were concentrating immediate efforts on a $10 million rollout of 56 new digital speed cameras on some of the country's most dangerous stretches of road by early 2016.
Three of them - two in Auckland and one in Wellington - will be used to catch red-light runners at dangerous intersections.
But once the rollout was completed, the police would want to keep increasing their use of new technologies to slow motorists.
"We are aware there's a possibility of using mobile point-to-point cameras," he said.
"This means we can have a camera in one location and another four to five kilometres down the road, and the two cameras can measure speed between them."
The technology is used in several European countries, some parts of Australia and in Britain, where a study recorded a 46 per cent decline in fatal crashes and 37 per cent fewer serious injury smashes along 51km of road in southwest Scotland since point-to-point cameras were installed in 2005.
An early version of the idea was trialled in New Zealand in the mid-1980s, when police used spotter planes to time how long it took vehicles to travel between large white strips painted on high-speed roads.
Mr Cliff told the Herald he had only a vague recollection of the trial, and expected it was abandoned as being too expensive.
But a camera manufacturer had indicated the possibility of using newer technology to similar ends, after Victorian police had found it effective in reducing average speeds.
"It forces people to measure speed across the whole journey, and it generates minimal numbers of [infringement] notices because it is a powerful deterrent," he said.
"It's more on long stretches like motorways, where you want to keep speeds nice and even."
He did not yet know if the new digital cameras could be adapted for that purpose.
Automobile Association spokesman Dylan Thomsen said his organisation would support the idea as long as police explained it fairly to drivers.
Road Transport Forum chief Ken Shirley also backed it in principle, as long as the technology did not prove too costly, adding to freight charges.
Mr Cliff told the conference the police and partner organisations such as the Transport Agency still had plenty of work to convince the public that speeding was socially unacceptable in the same way drink-driving was regarded.
Each 5km/h travelled above a speed limit doubled the risk of a vehicle being involved in an injury crash, and the likelihood for a car going 70km/h in a 60km/h zone was the same as one in which the driver's alcohol level was 100mg per 100 millilitres of blood.
That compares with the existing limit of 80mg, to be reduced to 50mg on December 1.
But Mr Cliff said the police had won a positive response after last summer's campaign against speeding.
Experts reviewing cycling safety after coronial concern at a spate of road deaths will recommend mandatory passing distances for motorists, and consideration of "side under-run" protection devices on trucks.
A 10-member panel appointed by the Transport Agent is also likely to recommend keeping helmets compulsory for road cyclists, but does not favour making high-viz clothing mandatory, its chairman indicated to a conference in Auckland yesterday.
Richard Leggatt told the NZ Traffic Institute his panel would recommend a mandatory buffer distance of one metre for vehicles passing bikes in urban areas at up to 60km/h, and 1.5m at faster speeds or on rural roads.
It would also recommend Government consider the "cost-effectiveness" of installing devices on trucks to stop cyclists being dragged under them, among other techno-logical improvements such as collision detection warnings and more mirrors.
Mr Leggatt, a former chairman of Bike NZ who is a director of several organisations including New Zealand Post, said the number of serious accidents involving cyclists and trucks was markedly higher than those involving buses.
He believed that was mainly because buses sat much lower on the road than trucks.
"If you fall off a bike you really only hit the side of a bus and roll away," he said.
His panel, appointed after a 2013 review by Coroner Gordon Matenga of 13 bike deaths, is due to present a draft report to cycling groups next week and then to a reference group for consideration next month, before recommendations are made for government response in December.
Road Transport Forum chief Ken Shirley said side under-run protection in countries such as Britain had proven ineffective.
But Assistant Police Commissioner for road policing Dave Cliff said it was "a great idea."