A man has drawn a green penis shape on a state highway in protest over a 'dangerous' bump in the road.

Geoff Upson first complained in October last year about an "unmarked speed bump" on State Highway 16 north of Auckland, near Kaukapakapa.

He said his complaint to the NZ Transport Agency (NZTA) was passed on to Fulton Hogan who he was told had the road maintenance contract for that section of road.

He said the speed limit on the road was lowered to 70km/h and then down to 50km/h after complaining.

But with no action to fix the bump, this week he decided to draw a penis around it and post a video highlighting the "dangerous" bump on Facebook.