As soon as the power goes off and the traffic lights are out, homeless men sporting bright-green high-visibility vests emerge apparently from nowhere and start directing the cars at a busy Johannesburg intersection.

South Africa is buckling under unprecedented power cuts, which are crippling everything from manufacturing to the flow of traffic.

But for Johannesburg's army of homeless people, the crisis is an opportunity.

Ordinarily, when stop lights go out, the police come and direct the traffic at city crossroads.

But the power cuts are so pervasive that there are not enough officers to cope -- and this is where the homeless step in, pocketing tiny donations from drivers in exchange for directing the traffic.

"Without us being around here it is causing a couple of accidents," Aubrey Ndlovu, a 31-year-old migrant from Zimbabwe, told AFP at an intersection in the affluent northern suburb of Bryanston.

South Africa's highway code says that at crossroads without lights, the first car to arrive has right of passage -- but the pecking order gets messy when the intersection gets congested and nobody can remember who next has priority.

The informal traffic wardens thus intervene to organise the flow.

"Even the small change people give us helps us get by," said Ndlovu.

Johannesburg police spokesman Xolani Fihla admitted that "a large amount of unauthorised people like homeless and vagrant people" were controlling the traffic during power cuts.

They are "doing a commendable job," he said, while emphasising that the city was not liable for any accidents that might occur under their watch.

"They do help a lot, but they are a risk at the same time," said Sphelele Mpukwana, a Johannesburg motorist, suggesting they be trained in traffic directing.

Ndlovu and his friend Ben Dube, 30, hope this will become true one day. Their current home is a spot under a local billboard.

Without training, they face a high risk of being hit by cars in a country where crashes kill thousands of people every year.

And not all drivers approve of what they are doing.

Some "swear at us, they are always in a rush," Dube said.

-Africa News