3 December 2013
Last updated at 13:11
A British company has demonstrated a prototype device capable of stopping cars and other vehicles using a blast of electromagnetic waves.
The RF Safe-Stop uses radio frequency pulses to “confuse” a vehicle’s electronic systems, cutting its engine.
E2V is one of several companies trying to bring such a product to market.
It said it believed the primary use would be as a non-lethal weapon for the military to defend sensitive locations from vehicles refusing to stop.
There has also been police interest.
The BBC was given a demonstration of the device at Throckmorton Airfield, in Worcestershire.
Deputy Chief Constable Andy Holt, of the Association of Chief Police Officers (Acpo), who has evaluated the tech, said the machine had “potential, but it’s very early days yet”.
At one end of a disused runway, E2V assembled a varied collection of second-hand cars and motorbikes in order to test the prototype against a range of vehicles.
In demonstrations seen by the BBC a car drove towards the device at about 15mph (24km/h).
As the vehicle entered the range of the RF Safe-stop, its dashboard warning lights and dials behaved erratically, the engine stopped and the car rolled gently to a halt. Digital audio and video recording devices in the vehicle were also affected.
“It’s a small radar transmitter,” said Andy Wood, product manager for the machine.
“The RF [radio frequency] is pulsed from the unit just as it would be in radar, it couples into the wiring in the car and that disrupts and confuses the electronics in the car causing the engine to stall.”
He did not provide other specifics. However, the Engineer magazine has reported the device uses L- and S-band radio frequencies, and works at a range of up to 50m (164ft).
Some experts the BBC has spoken with suggested that turning off the engine in this manner would not stop vehicles rapidly enough. Others worried about what effect it might have on a car’s electronic brake and steering systems.
But E2V said the risks were lower than with alternative systems.
Acpo suggested the machine’s ability to stop motorbikes “safely” could prove particularly useful.
Mr Holt noted that the tyre deflation devices used by some police forces posed the risk of causing “serious injury” if used against two-wheelers.
E2V added that its device could also be effective against other types of vehicles, including boats.
But because the device works on electronic systems, he acknowledged that it would not work on all older vehicles.
“Certainly if you took a 1960s Land Rover, there’s a good chance you’re not going to stop it,” Mr Wood said.
The firm added that it did not believe the RF Safe-Stop posed any risk to people using a pacemaker.
Listeners in the UK can hear more about the device on BBC Radio 4’s PM programme between 17:00 and 18:00 on Tuesday.