How do speed cameras work? The types of speed cameras on UK Roads including manned and fixed

There are a number of types of speed cameras. The question 'how do they work?' can only be answered nowadays in relation to each specific device. When speed limits were first introduced in the UK, a common police method of checking the speed of cars was to measure out a distance along a road and time a driver's journey between two points with a stopwatch. Much has changed since, and the last twenty years has seen the introduction of an aggressive government policy to clamp down on speeding by introducing both fixed cameras and more sophisticated police manned speed check equipment.

Speed camera and silver peugeot

Now more than ever, the motorist is at risk from losing his or her licence and job for the sake of what was once regarded to be a less serious offence. The police now have an array of different devices and techniques designed to detect speeding drivers.

People who drive many miles are particularly vulnerable, as they are more likely to slip up on roads with variable speed limits or roads that they have not driven on before. The penalty points system means that someone who drives 3000 miles over three years and receives 9 points for speeding offences in this period keeps his or her licence, whereas a van driver who drives 100,000 miles over the same period but receives 12 points for similar speeding offences could lose his or her licence. In the second example, the van driver could be argued to be more than 25 times less prone to speeding on any given journey but is treated more harshly.

Gatso Fixed Cameras and other fixed types of speed camera

Gatso work by photographing a car over a marked distance in the road over a very short time period. They are a fixed device, and they do not need to be manned, although most gatsos use conventional 35 mm camera film which needs replacing regularly. The device must be calibrated, and show certification for this, and must also have the relevant Home Office type approval, which must approve the device, and also the type of use the device is set up for.

How do speed cameras work if they are the Gatso type? Gatso cameras take a picture from behind, which makes it almost impossible to identify the driver from the photograph. If several people had access to a car but the keeper does not know who was driving at the time, then the CPS will usually prosecute for Failure to Give Information as to the Driver.

TruVelo Fixed Cameras

TruVelo cameras work on a similar principle to Gatso Cameras, except they take a photograph of the car from the front. This is to assist keepers of motor vehicles to identify the driver. Gatso cameras were unable to be adapted to do this because the flash of the camera could cause an accident if coming from the front. TruVelo cameras use an infrared flash. The same issues relating to calibration and type approval that apply to Gatso cameras apply to TruVelo cameras too.


Since the introduction of mobile laser devices such as the LTI2020 or Prolaser, radars are rarely used by police. Typical hand held variants include the Kustom Falcon and the Speedar. The radar method is generally less reliable than laser, as targeting a portable radar device has potential difficulties.

One problem is potential interference from items at the side of the road that can compromise the accuracy of the reading, or even measuring the speed of the wrong car where another car is in view.

The wave length of the radar used by police can be very long (up to several hundred feet). Each device requires calibration and the relevant home office approval for the type of use.  The use of the device should be in accordance with the ACPO guidelines.

Laser devices

Laser devices are a new and controversial method of speed detection, wand they have been adopted almost universally by police forces in England and Wales. The fact that most UK police forces have adopted the LTI2020 Speedscope and ProLaser at great public expense means that any of the faults that have since emerged in the technology and its reliability are unlikely to cause a mass recall of the device. Each LTI2020 in operation has been bought at a cost the taxpayer of an estimated £4500.

Lasers operate at a very narrow wavelength and are precise in comparison with radars. Unfortunately they are also very sensitive, and officers have to operate them in strict accordance with the guidelines laid down in NPCC, as well as the manufacturer's guidelines.

The potential for ‘slip' is a potential issue, and the device has to be trained on a flat surface of a vehicle, often several hundred metres away, for a third of a second without any movement in the operator's hand. So much as a millimetre movement for this period can render the reading invalid, and courts, when provided with expert evidence on this, have often decided that the prosecution is not made out.

Simply putting the prosecution to proof with regard to the certification, checks, and correct usage of the laser device often results in charges being dropped before trial.


Vascar is technology which enables police officers to time another car's journey between two points. Vascar is an acronym which stands for Visual Average Speed Computer And Recorder. It falls into 2 different systems Vascar 5000 and the integrated video system Vascar V Plus.

Vascar 5000

This system is essentially nothing more than a timing computer, with a stopwatch mounted inside the police vehicle, with a calculator for speed. The measured distance between two points is entered into the device. An officer observes the marked out area, pushing the timer button when a car passes the start and finish point. The machine then gives the average speed.

The potential for an inaccurate reading comes through the officer's capacity for error. Unless the measurement is taken over a long distance, the reaction times of the officer, even if they were excellent, could render a Vascar reading unreliable, with a margin of error of 10 20 % not being out of the ordinary.

Vascar V Plus

This is a system which incorporates the technology used in the Vascar 5000, as well as windscreen mounted video system. The strength of the evidence produced by this system is of course greater than the Vascar 5000, as video corroboration of an offence can be provided to the court.

Speed Camera Detectors and Jammers

There are certain devices available in the UK which assist the motorist in combating speed detection devices such as lasers etc. Some of them are potentially illegal. We have attempted to summarise the position below. Please note that the position relating to individual devices may be different. The information below is not legal advice, and we advise anyone in doubt to contact the authorities and manufacturer in respect of individuals. Our advice is not to use any device which either detects or interferes with any individual speed detection device.

Radar and Laser Detectors

The current position appears to be that these devices are legal to own and use, although the Road Safety Act 2006 has scheduled their prohibition. However, the final part of this becoming law is the ‘Statutory Instrument' which has still not been passed by the Government. In the circumstances, these devices appear to be legal.

However, the science behind a laser device is such that it can only be detected a split second before the laser hits a car, so is probably of no use to anyone anyway.

Radar and Laser Jammers

The law on the use of these devices is clearer. Even though the same Road Safety Act (2006) outlaws the use of these items, extensive legislation relating to obstruction of police and perversion of the course of justice exists. These laws are phrased wide enough to mean that any motorist using a jammer device could be risking a custodial sentence and a conviction for a serious criminal offence.

Sat Nav units showing Gatso Locations

These types of units are legal, as they only indicate information that is already freely available from Local Authorities and Police Forces. They also indicate areas which contain accident black spots, where Gatsos are often located, so are largely supported by the Government, outwardly at least.