High earning speed camera upgraded to catch more drivers

South Australia's highest-earning speed camera is being upgraded to catch even more motorists.

The fixed camera on the South Eastern Freeway at Leawood Gardens is being relocated a short distance up the hill and a high-tech replacement installed, specifically aimed at detecting speeding trucks and buses.

Work at the site is underway, with the foundations currently being ripped up.

But the upgrade has infuriated motorists.

The State Government says the move will enable the camera to catch more speeding trucks and buses.

"It's just over the top I reckon," one truck driver told 9News.

Last year, the camera raked in nearly $4 million in fines, equating to around $11,000 a day, but the State Government insists the upgrade is not about revenue raising. 

"We know that's a notorious intersection, obviously, and this is a safety operation to make sure that trucks and buses are detected," Police Minister Corey Wingard says. 

Questions as to why the camera didn't already detect speeding buses and trucks have been put to the Transport Department, which is yet to respond. 

It's also unclear when the new camera will start operating.