Drone joins battle for coastal roads

It sounds like a swarm of mosquitos and looks like a flying spider but it could save New Zealand's coastal roads.

Southern roading company Fulton Hogan has begun using a six-bladed hexi-copter drone fitted with a video camera to survey North Otago's eroding coastline.

The survey is for the Waitaki District Council, which will use the footage to find and urgently shore up hotspots where the road is threatened with undercutting by the sea.

Much of the East Coast is being quickly eroded, in places averaging up to two metres a year.

The council has been caught out several times in the past five years by unexpected cliff collapses.

The operation should yield four or five hours of footage - from above, below and around the cliffs - which will be used to build a three-dimensional view of the most affected places.

It will also give a base of information, which the council can use for comparison in six months' or a year's time or after a big storm event.

Fulton Hogan laboratory manager Sean Connaughton said the drone was much safer, and gave a bird's-eye view like no other.

"It's a fantastic tool, it's a fantastic piece of kit... Used well and used properly, you can get a view that would otherwise take a lot of effort to do."

Using the drone costs about $3000 for a day's survey, and does away with expensive expeditions involving boats and staff abseilling down cliffs.

Waitaki council roading manager Michael Voss said it was exciting because, for his small council, surveying the coast had suddenly become affordable.

Mr Voss said he expected a drone would soon become standard kit for every council in the country once people discover the aircrafts' potential.

Operating drones does come with risks, however, with an investigation currently under way into a reported near-miss with a passenger plane above Kaiapoi on Friday.