Grit-blasting robots clean Sydney Harbour Bridge

Australia is using two grit-blasting robots to clean the Sydney Harbour Bridge before it is repainted.

The robots shoot out compressed air to cut through rust and old paint on the famous Australian landmark.

The exercise is billed as one of the world's biggest maintenance programmes.

Cleaning the bridge is considered dangerous, forcing workers into uncomfortable poses and bringing risk of exposure to asbestos and old paint.

The robots, which were developed at the University of Technology, Sydney (UTS), operate by scanning the area, creating a 3D map, and working out how much force they should apply using high-pressure cleaners to strip paint from the bridge.

"We now have two [operational], autonomous grit-blasting robots on the Sydney Harbour Bridge, which is a world-first technology," Martin Lloyd from UTS said, adding that the blasters on the robots were powerful enough to slice through people's clothes and skin.

The operation is the result of a collaboration between the university and Australia's Roads and Maritime Service.

"The job [of cleaning the bridge] is very risky [for humans] - the bridge vibrates because of the traffic and it has complex geography - which is why we approached UTS to see if a machine could do this kind of work," Waruna Kaluarachchi from the Roads and Maritime Service said.

Nicknamed "The Coathanger" because of its distinctive shape, the bridge was opened in March 1932, the BBC's Phil Mercer in Sydney reports.

Repainting work is a never-ending task, and the two robots are to remain a permanent part of the maintenance team, our correspondent adds.