NEW speed cameras will be used on the South Eastern Freeway within weeks, potentially reaping millions of dollars in fines from the 10 per cent of drivers who are speeding on the motorway.

The Transport Department has confirmed that infringement notices will be issued to speeding motorists and truckies heading down the freeway from Crafers into Adelaide from this month, more than two years after the cameras were installed.

The Transport Department will not confirm the exact location of the two new cameras. However, The Advertiser has previously reported that one camera is at Crafers and the second is near the Mt Osmond exit.

A seven-day survey last month caught more than one in ten vehicles driving down the freeway at least 5km/h over the 100km/h limit.

Of the 166,934 cars caught by the survey camera, which is on the city side of the Heysen Tunnels, more than 18,300 were breaking the law. This included 3339 who were travelling 10km/h in excess of the speed limit.

media_camera FAST CASH: Speeding drivers on the South Eastern Freeway are set to boost the state's coffers when the cameras go up in the next few weeks.

If these drivers had been fined, they would have paid a combined $3.4 million.

While the number of drivers speeding is likely to drop once they realise the cameras are activated, they are still expected to make a significant contribution to police estimates of a $23 million boost to traffic fine revenue this financial year.

The new cameras are the first in the state to "operate in a 'variable speed limit' environment where the speed limit can change across the day dependent upon road conditions'', according to the department.

"It is the first time this technology has been used in South Australia and it has been necessary to undertake a significant testing period to ensure fail safe operation of the system,'' a department spokeswoman said.

They are among 30 extra speed cameras introduced on South Australian roads since last year.

Even though traffic experts believe fewer people will speed once they know the cameras are operational, they still expect the annual revenue raised on this stretch of the freeway will easily outstrip last year's record $982,000 generated by the fixed camera at Glover Ave, near Adelaide High School.

The SA Freight Council supports the new cameras, describing the rate of speeding detected by the survey as "massive''.

"The amazing thing is there's a spot on SA roads where so many people are speeding,'' council chief executive officer Neil Murphy said.

"Given the volume of traffic, you could expect these cameras will generate a record number of fines.''

RAA road safety manager Charles Mountain said there was "the potential with three lanes of traffic'' for this section of road to catch the highest number of speeding drivers in the state.

"Certainly, from a road safety point of view, we welcome these cameras coming on line, given the amount of damage vehicles can do travelling at these speeds,'' he said.

The two new freeway cameras - costing a total of $620,000 - were originally installed in August 2011 to catch heavy vehicles breaking the 60km/h limit between Crafers and the city.

The reduced speed limit was introduced after two fatalities involving heavy vehicles in 2010.

In the past two years, the cameras have been reconfigured to detect semi-trailers exceeding 60km/h, vehicles exceeding 100km/h, and vehicles exceeding reduced speed limits for road work or weather conditions.

Road Safety Minister Michael O'Brien said "all revenue from anti-speeding devices is returned to road safety through the Community Road Safety Fund.''

"Speed cameras are about saving lives and preventing serious injuries by getting motorists to slow down, drive to the conditions and not exceed the speed limits,'' he said.

The cameras' ability to detect speeding breaches across different speed limits would provide "an additional measure to ensure people drive safely into Adelaide from the freeway.''

"These new safety cameras need to be able to detect different vehicle types such as heavy vehicles (with five or more axles), which are required to travel at different speeds to light vehicles,'' he said.

In contrast to the 11 per cent of all vehicles detected speeding by last month's survey, only 4 per cent of the 5438 trucks monitored exceeded the 60km/h limit.