An Auckland man has spraypainted an outline of a large penis on a section of State Highway 16 in an effort to force NZTA to repair the road.

Self-styled safety campaigner Geoff Upson posted a video to Facebook, showing vehicles travelling over a bump in the road on State Highway 16 north of Kaukapakapa.

The video also shows a large green phallus painted on the road which Upson admitted to painting, saying: "To be honest it's unfortunate that things have got this bad. I wouldn't have done something like this if I hadn't got so upset and disappointed with the level of service. We pay huge amounts of money with road user charges and fuel tax. A basic level of responsibility should be a flat road surface."

Upson spoke to the Herald about the action saying: "I never planned on doing this and it's not something I plan on doing again but there's a point where I sort of feel I'm cornered. If I get results from doing things the proper way then this would never happen again."

Locals were quick to support Upson, sharing their own stories of driving the road, with one saying that "my jetski trailer bounces heavy at 90".

Another said: "That part of the road is ridiculous. I always forget about it and cringe when I hear my suspension crunch going over it."

A local pet owner complained: "I have dogs and I can't go down even at 50km. They all leave the van floor and tumble over in the van."

One local complained the problem was not an isolated one, claiming that the quality of the roads in the area is "so bad" and labelling the road a "death trap".

Upson said he would be willing to face the court for his actions, saying "if the police would like to charge me with vandalism, that's the law. If I've broken the law, I've broken the law."

Upson also admitted to driving above the speed limit on that section of road to show that his car could become partially airborne when driving over the bump, but claimed he was drively safely: "I drive a 2017 double cab 4WD ute. We're talking about a vehicle that's built to handle this kind of road.

"It's more about the driver. There's a lot of incompetent drivers on the road so I would never suggest for anybody to drive above or beyond their driving ability and skills."

Following inquiries from the Herald, NZ Transport Agency's Northland System Manager, Jacqui Hori-Hoult, confirmed that the agency has a programme of works to carry out another levelling of the road next week, weather permitting.

Hori-Hoult added: "Our team is constantly on the state highways to address any safety issues or hazards."

The spraypaint was later painted over by contractors. (Photo / Supplied)

Asked how he felt about local children seeing his protest, Upson said: "I think if children are sheltered and not taught things that are a part of the real world then these things will come as a huge shock later in life. I think it's perfectly acceptable for children to be exposed to ordinary things in the world.

"If their parents are having trouble having a laugh about it then maybe they need to have a glass of wine and then try and explain it to their kids."

This is not the first time that Upson has used this technique to bring attention to roading issues.

In 2018 he drew similar graffiti on nearby Kahikatea Flat Road and succeeded having potholes filled after a social media outcry and media attention.

NZTA condemned Upson's decision to spraypaint the road: "Mr Upson has placed himself in an area of risk and may cause a bigger distraction by spraypainting the road. The paint has been removed from the road today.

"If members of the public want to report hazards on state highways or highlight any concerns, we encourage them to call our 24/7 freephone 0800 4 HIGHWAYS."

Chris Penk, National MP for Helensville, said to the Herald: "It's not a method of advocacy that I would encourage and certainly there are other ways that we can get in touch with NZTA on behalf of constituents but, having said that, I think that the frustration that underlies it is worth acknowledging."

Asked for his personal view of the condition of State Highway 16 as it runs through his constituency, Penk said: "It's good in parts, which I suppose is a way of saying that there are definitely bits that do need attention from time to time. It's a long stretch of road and there are areas that could certainly do with a lot of attention."

In a statement released to the Herald, NZTA added: "We are aware of local feedback about the state of the road surface on SH16 and we are constantly monitoring that it is safe for road users.

"Two separate sites have been identified for priority work where the road has been affected by subsidence. Work will start on the first site next week near Omeru Reserve, weather permitting. The second site is south of Farmer Rd on SH16.

"Work is also due to start this year on safety improvements on State Highway 16 between Brigham Creek and Waimauku.

"This will include flexible safety barriers to stop vehicles running off the road or colliding head-on, improvements to facilitate turning vehicles and widening the road to allow room for cyclists. This project is the first part of a bigger package of work aimed at addressing growth and congestion in Auckland's North West."