Telegraph | September 15, 2008

Drivers could have their speed controlled by satellite to stop them from breaking the limit following a Government trial of new technology.

Cars fitted with the system would have their speed automatically monitored by satellites, which would also be programmed with the speed limits for different roads.

A motorist who tried to accelerate beyond the speed limit would find the system stopping the car from going any faster or issuing a warning instructing them to slow down.

The Department for Transport is set to back the system known as Intelligent Speed Adaptation. It follows lengthy trials conducted in Leeds in where cars have been fitted with the sophisticated satellite navigation system.

The Department for Transport said that the installation of the technology would be voluntary, but it is already in talks with the motor industry over how it could be made available for those who wanted to buy it.

Three types of the technology could be made available.

The first, known as "advisory", would stop short of actually slowing the car down and would instead issue a voice alert reminding the motorist what the speed limit is.

A second version would either apply the brakes or cut the fuel supply to the engine, slowing it down to the speed limit, but a driver would be able to override the system – either by depressing the accelerator pedal firmly or pressing a button.

The third would take over complete control of the car and the driver would not be able to override the system at all.

However, the biggest hurdle is the creation of a digital map of Britain, which would have to contain the speed limits on every road. A spokesman for the DfT said it was working with councils over the collection of data to enable a map to be produced.

However, no timescale has been set for when such a map would be made available. Several companies have run trials of the system, including Siemens, which used a version which posted the speed limit onto the windscreen when the driver went too fast.

In Britain it also produced a test version which slowed the car down on certain occasions – such as when it was going past schools. According to a poll carried out for the DfT, 54 per cent of motorists would be willing to have the system installed in the car, if it was voluntary.

On average they would be prepared to pay £111 for the equipment, although some believed it should be provided for nothing.

Rob Gifford, executive director of the Parliamentary Advisory Council for Transport Safety, said the technology could be very effective. He said: "Its accident savings are phenomenal, particularly in injury crashes.

The number of deaths that could be prevented is also substantial, especially when it comes to those outside the vehicle rather than inside." But the AA sounded a note of caution.

"I think it isn't a bad idea," said Andrew Howard, the head of road safety. "But there are a number of issues, such as accuracy and how it will work for example when there is a slow service road running alongside a major one."

The Government yesterday named the contractors who will be responsible for conducting pilot schemes for road pricing. Ruth Kelly, the transport secretary, was accused of having a "completely blinkered approach" by Theresa Villiers, her Tory shadow, who said the announcement brought national road pricing a step nearer.