New point-to-point cameras on the South Eastern Freeway in South Australia are being switched on to save lives, not collect revenue, the state's Road Safety Minister has said.

The new safety cameras will be activated on December 15 over a 13.5-kilometre stretch of highway, between Mount Barker Summit and Callington.

The cameras will detect the speed of vehicles travelling in both directions.

Transport Minister Tony Piccolo said point-to-point cameras have already helped reduce speeding on the Dukes Highway, Port Wakefield Road, Sturt Highway and Victor Harbor Road.

He said the latest installation has nothing to do with collecting money from speeding drivers.

"I would prefer that people just got the message and not sped and we didn't have to collect the expiation notice," Mr Piccolo said.

"Because unfortunately the reality is we spend a lot more money than we collect in expiation repairing people back to health as a result of car accidents and many lose their lives."

One more point-to-point camera on the Northern Expressway is still to be activated.

Eight fatalities on freeway over five years

The cameras calculate the average speed of a vehicle between the cameras, as well as the vehicle's actual speed at each camera location.

Mr Piccolo said cracking down on speeding could save lives.

"Fatalities and serious injuries in regional and rural communities continue to be an issue in South Australia," he said.

"Speed contributed to 31 per cent of regional and rural fatal crashes between 2010 and 2014."

He said data showed that from July 2010 until June 2015 there had been 156 casualty crashes resulting in eight fatalities, 28 serious injuries and 174 minor injuries on the South Eastern Freeway between the Old Toll Gate to Old Princes Highway intersection at Swanport.

Mr Piccolo said statistics also showed that up to 47,000 vehicles use the freeway on a daily basis and about 13,000 vehicles use this specific stretch of the freeway enforced by the new cameras.