The effort to reduce the speed limit on a road in the Adelaide Hills has taken an unusual direction, as a resident has tackled the issue personally using a piece of plastic and some screws.

A 60km/h sign on Ambleside Road in Hahndorf was switched to 50km/hwithout the knowledge of authorities.

“It’s bizarre and it’s illegal,” Transport Minister Tom Koutsantonis said.

“I know they’re well intentioned but we can’t have people doing that – it’s dangerous and inappropriate.”

Even though some community members have raised worries about speeding on Ambleside Road and back a decrease in the speed limit, they emphasize that any alterations must proceed through the appropriate procedures.

“I don’t think we’ve really got the right to change signs on the road. It should be done through the right channels,” one resident said.

A man believed to be responsible for the alteration was approached for comment but declined to speak on camera.

“My very strong advice is to stop,” Koutsantonis said. 

“Yes, ingenuity yep, tick. Illegality? Unfortunately, yes, that is a tick as well, and you can’t do that.

“And if you get caught, you can go to jail.”

The fake speed sign has since been removed.

Meanwhile, it’s believed a load limit sign on the same road has also been tampered with.

It’s meant to say 15 tonnes, but the “1” has been removed.