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Road-rule enforcement camera

A road-rule enforcement camera is a system including a camera and a vehicle-monitoring device used to detect and identify vehicles disobeying a road rule or road rules. Common examples include the following:
  • Speed cameras for identifying vehicles travelling over the legal speed limit.
  • Red-light cameras for identifying vehicles proceeding through red lights.
  • Bus-lane cameras for identifying vehicles traveling in lanes reserved for buses.
  • Toll-booth cameras for identifying vehicles proceeding through a toll booth without the toll being paid.
There are systems that are combinations of the above - for example, some systems detect both red-light infringements and speed infringements.

Table of contents


A Dutch company called Gatsometer BV, founded by the 1950s rally driver Maurice Gatsonides[?], invented the red-light camera, developed the first radar for use with road traffic, and is the world's largest supplier of speed camera systems. Because of this, in some countries (the United Kingdom for example) speed cameras are sometimes referred to as "Gatsos". They are also sometimes referred to as "photo radar", even though many of them do not use radar.

The first systems introduced in the late 1960s used film cameras[?] to take their pictures. From the late 1990s, digital cameras began to be introduced. Digital cameras can be fitted with a modem or other electronic interface to transfer images to a central processing location automatically, and so they have advantages over film cameras in speed of issuing fines, and operational monitoring. However, film based systems still generally provide superior image quality in the variety of lighting conditions encountered on roads, and new film based systems are still being sold.


Vehicle-detection systems used in road-rule enforcement cameras include the following:

  • Piezo-electric strips - pressure sensitive strips embedded in the roadway (a set distance apart if speed is to be measured - typically 1-3 meters).
  • Doppler radar - a radio signal is directed at the vehicles and the change in frequency of the returned signal indicates the presence of a moving vehicle and the vehicle's speed.
  • Loops - inductive loops embedded in the roadway detect the presence of vehicles, and with two loops a set distance apart vehicle speed can be measured.
  • Laser - the time of flight of laser pulses is used to make a series of measurements of vehicle position, and from the series of measurements vehicle speed can be calculated.

Systems can be car or van mounted, hand held, or fixed site. In car mounted systems, cameras and radars or lasers are fixed to a car. When deployed, the car is parked beside a road, and any speeding vehicles driving past are photographed. Red-light cameras are typically fixed site type systems. Many speed cameras are also fixed site type. Fixed site type systems are typically mounted in boxes on poles beside the road. They are also often attached to existing gantries that hold up signs over the road, and to over passes or bridges.

Speed camera systems that measure the time taken by a vehicle to travel between two fairly distant sites (from several hundred meters to several hundred kilometers apart) are also being developed and introduced. From the elapsed time over the known distance, a speed infringement can be detected, or in the case of truck drivers driving long distances, avoidance of legally prescribed driver rest periods can be detected. Such systems take a picture of every vehicle passing the first site, and every vehicle passing the second, then find matches between the images from the two sites. Most commonly, this matching is done by using automatic number-plate recognition[?] systems. Such systems have been tried and/or deployed in only a few road jurisdictions in the world.

Verification and System Testing

The pictures taken by road-rule enforcement cameras must typically be viewed by a person before any infringement notice or ticket is issued to the driver, and judged to be satisfactory or not. This step is known as verification, and is a standard legal requirement in nearly all jurisdictions. Verifiers typically must check some or all of the following:

  • that there is no sign of interference with the vehicle detector by objects other than the alleged speeding vehicle,
  • that the number plate is unambiguously readable according to a legal standard,
  • that the make and model of vehicle matches that recorded by the licensing authority for the number plate,

and in some jurisdictions

  • that the appearance of the driver in the images is adequate in some way - for example, does it match the picture on the driver's license.

In most jurisdictions, verification is carried out by the police force, although in many places it is carried out by private companies on a fixed price basis under close police supervision. Also typically, cameras must undergo approval testing and operational testing to ensure that they function adequately. In the US, typically all installation, operation, and verification procedures are carried out by private companies that receive payment based on the number of infringements they issue, and often under no testing regime whatsoever.

Depending on the number of things that need to be identified in the images and the quality of the camera equipment, somewhere between 35% and 80% of infringements result in a notice being issued to the owner of the vehicle. A legal requirement for driver identification reduces the prosecuting rate dramatically.


In September 2001, the pictures from the San Diego red light camera systems were ruled inadmissable as court evidence (USA Today article (http://www.usatoday.com/life/cyber/tech/2001-09-05-judge-nixes-red-light-cams.htm), Judge's ruling (http://freedom.house.gov/auto/cases/sdmotion.asp)). The camera program was operated and paid for according to practices common throughout the US. Such practices give a financial incentive for companies to verify against drivers in cases of doubt, and this was found to be unacceptable, as was the low level of involvement by the city and police. Despite the ruling, such verification and camera operation practices continued on a widespread basis in the US.

In January 2002, a speed camera case was dismissed in Denver, Colorado on similar grounds of pay per infringements being illegal, and lack of police involvement in issuing of tickets.

In the late 1990s in a number of jurisdictions, there was a degree of controversy surrounding the deployment of increasing numbers of speed and red-light cameras. Police and government were accused of "Big Brother tactics" in over-monitoring of public roads, and of "revenue raising" in applying cameras in ways to increase government revenue rather than improve road safety. In some places, for example the province of Ontario, Canada, and the state of Hawaii in the USA, camera programs were aborted or withdrawn due to public outcry. Often when camera deployment has been accompanied by large scale advertising campaigns explaining the justification and planned effects of such cameras, the public has accepted their use on a large scale. In other places, public responses have included spectacular vandalism of camera systems including attacks with explosives, tractors, cutting equipment, incendiary devices, rifles, and even attacks on camera operators, as forms of civil disobedience and protest.

External Links

example images

  • UK pics (http://www.stvincent.ac.uk/Resources/Physics/Speed/road/redlt)

against enforcement cameras


for enforcement cameras

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