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TYPES OF CAMERA
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LRSP currently operates two different types of fixed safety camera –
the Gatso and Truvelo.
Gatso Camera:
The Gatso camera works by radar, to measure the difference between
the frequency of a transmitted radio wave and that of the return
wave reflected by the moving target vehicle.
The difference between the frequencies of these two waves can be
easily calculated to represent the speed of the moving vehicle,
which triggers the system if it exceeds the pre-set threshold. Two
pictures are then taken of the rear of the vehicle, and stored
within the wet film cassette until it is processed.
Truvelo Camera:
The Truvelo camera is installed at permanent sites at the roadside.
Two pairs of sensors are installed in the surface of the road, and
the system measures the time taken for the front axle of a vehicle
to travel from sensor 1 to sensor 3, which represents a distance of
1.5 metres.
Sensors 2 and 4 also provide a measurement of this speed and if the
two differ by more than 2mph, they are rejected and processed no
further. If the measurements are reliable a single image is taken of
the front of the vehicle and stored on wet film.
All cameras are calibrated so that only vehicles travelling above
the limit are seen and photographed by the camera.
White line markings on the road surface, five feet apart, provide a
secondary back-up check on distance travelled for the GATSO sites,
verified by an operative who examines the film taken by the camera.
Calibration Certificates
Each camera is issued with a calibration certificate by the relevant
manufacturer. To view representative examples of the large number of
certificated held by the Partnership,
Click Here |
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