Staff at the agency charged with making our roads safer have been caught illegally hooning in work cars at least 8500 times in nine months - twice at 145km/h - and not one will get a ticket.

The speeding staff at the NZ Transport Agency include a member of the senior leadership team and a handful of managers.

In a three-month sample of the data, at least 45 of NZTA's 139 cars were found to have been driven "consistently at speeds over 110km/h and sustained high speed over a number of kilometres".

A NZ Herald analysis of data obtained through the Official Information Act found 8500 occasions on which NZTA cars were driven faster than 110 km/h - well over any unofficial tolerance applied to speed enforcement. There were 910 instances where the cars were driven at speeds greater than 120km/h - and 130 instances of speeds more than 130km/h.

Of those, eight people exceeded 140km/h, with at least one going more than 145km/h.

The Herald has turned NZTA's data into an interactive map, allowing readers to see what the road safety agency has done in their neighbourhood (desktop version above, mobile version at bottom of the article).

NZTA is the government department responsible for road safety and for setting speed limits. It has repeatedly pushed through taxpayer-paid advertisements the message "Speed Kills".

Its website warns: "The single biggest road safety issue in New Zealand today is speed - drivers travelling too fast for the conditions. In 2013, speeding was a contributing factor in 74 fatal crashes, 305 serious injury crashes and 988 minor injury crashes."

####Minister furious Minister of Transport Simon Bridges described the data as disappointing and embarrassing. "To say I'm unimpressed would be one of my big understatements. I'm very disappointed ... You've got a government agency here that is a key player in road safety and in many cases it has not led by example."

Mr Bridges, who has not had a speeding ticket since becoming an MP: "That's certainly something I don't want to be. I've directly contacted both the chair and chief executive on learning about this. I've made my views and expectations crystal clear. I've sought assurances from them both that ... speeding will come down. It is embarrassing."

Chief executive Geoff Dangerfield said the speeding was "unacceptable". He said staff identified as exceeding the speed limit have "had a formal conversation with their manager". Asked if that was the same as a verbal warning, he agreed.

Mr Dangerfield said further beaches would be considered against the agency's Code of Conduct, which every staff member had to follow. Breaches could result in dismissal, he said.

The information was gathered through GPS units which Mr Dangerfield said had been installed for health and safety reasons. "Now that we have this information, it's how we use it to turn the situation around."

He said none of the staff would be referred to police for enforcement action. "None of these things in the data have resulted in any infringement notices at all. It's not right thing for us to hand this over to police. We didn't do this from a sanctions point of view but from a health of safety point of view."

####'Message not getting through' The discovery of excessive speed among its fleet of cars led to a report to NZTA's senior leadership team in March. It told bosses the GPS data came about as part of a "Helping You Stay Safe" campaign aimed at those driving NZTA cars. Part of the programme was replacement of cars and introduction of GPS, of which staff were informed.

The report to the senior leadership team pulled out data from January showing there were three occasions where cars were driven over 131km/h and one case of a car being driven at 135km/h for a sustained period.

In February, speeds were higher - the GPS data showed four cases of cars travelling at 135km/h for sustained period and one case of a driver hitting 144km/h.

The report read: "It seems our messaging about safe driving simply isn't getting through." The report to NZTA's senior executives included a tweet from Auckland motorist Monica Wales saying: "I find it amusing that the one person speeding on the north-western (motorway) tonight was in a NZTA branded car."

Ms Wales told the Herald today she found it "hilarious" to see an NZTA car tearing down the motorway. "It's ironic of all the people not working with the system, it was them."

Even though the issue was flagged at a senior level, the OIA material confirmed the agency did not tell Transport Minister Simon Bridges about the speeding until the Herald sought the data.

The NZTA-supplied GPS data does not show whether the excessive speeds happened in 50km/h zones or on open road where the limit is 100km/h.

The GPS system tracks exactly where the speeding happened but NZTA did not check whether staff sped through school zones, shopping centres or on the open road.

####Fines and suspensions The 145km/h breaches - one in November 2014 and one in March - would have earned the drivers a $510 fine and 50 demerit points. NZTA's own website warns drivers that if they "accumulate 100 or more demerit points in any two-year period, your licence can be suspended for three months".

Data showed that NZTA cars exceeded the 100km/h speed limit 34,000 times in nine months and went over 110km/h on 2000 occasions.

In a recent research report, NZTA stated: "Achieving a road network with safer speeds, or one where the travel speeds are unlikely to cause fatal or serious crashes, is one of the four elements of a Safe System approach, adopted by the NZ Transport Agency."

The Safe System approach is the underpinning philosophy behind the government's Safer Journeys road safety strategy. NZTA stated: "Speed will be managed to survivable levels through a wide range of techniques such as greater use of technology and speed limits that are appropriate for the road."

In public relations material pushing the strategy, NZTA said it was one of the agencies critical to the strategies success. "We need everyone to play their part and do what they can to keep themselves, and others, safe on the road."

The speeding by staff appears to align with NZTA's 2013 survey of public attitudes to speed, which found 86 per cent of those surveyed believed speed limits on roads were about right. Only 7 per cent of people found they were too low. However, the same survey also found one in six people believed the risk of a crash when speeding was small if care was taken. One in four people surveyed said the risk of being caught speeding was low.

NZTA has been at the centre of a number of bungles in recent times. A law had to be passed with urgency to retrospectively enforce thousands of speeding fines after an oversight saw speed limits lapse on roads across the country. NZTA's new car registration system wound up error-ridden after mistakes with the ACC component. And Mr Bridges found himself in hot water when he used public servants to provide advice which was then used in the Northland byelection.

Labour transport spokesman Phil Twyford said he would expect the issue to be treated seriously. "The bureaucrats make the rules but they don't abide by them. Speed limits are there to save lives but these people have been treating them as minimums. They should be leading by example."

Green Party transport spokeswoman Julie Anne Genter said NZTA needed to hold itself to a higher standard and should use the GPS information to drive a culture change.

"It's not a good look for them. The behaviour of employees needs to change."