Traditional cameras capture speeders in one section of a road
Tests are taking place in the UK of new speed cameras that combine number plate recognition and satellite technology.
The SpikeSpike devices from US firm PIPS Technology are among the latest examples of average speed cameras.
They work out how fast a vehicle is going after capturing an image of its licence plate at two locations.
The cameras are being trialled in Southwark, south London, and on the A374 in Cornwall, MPs on the Commons transport select committee were told.
To date, average speed cameras in the UK have been used on single stretches of main roads.
PIPS Technology says the SpeedSpike devices could be placed on motorways, A roads, rat-runs and in areas surrounding schools.
The Tennessee-based firm, which has offices in Eastleigh, Hampshire, also created the Spike Automatic Number Plate Recognition camera used in London's congestion charging zone.
In its product description, PIPS Technology says the average speed data calculated by its cameras always errs "on the side of the driver", with precise clock timings set by using the Global Positioning System (GPS).
In a written answer to the select committee, the company said its test sites were in Salter Road in Southwark and the A374 from Torpoint to Antony.
Paul Watters, AA head of public affairs, said while it supported speed cameras, there were worries over calculating average speeds over longer distances.
"We have some concerns about how far these systems extend along roads with many different speed limits impacting on a driver's journey, how well drivers understand them and how well the zones are signed," he said.
"Camera enforcement is now high profile with conspicuous cameras and signing - we hope that continues.
"With new complex technology comes the risk of errors and so the government must issue clear guidance on how these systems should be used."
The Home Office has declined to comment on the trials.