HOW
THEY WORK
Gatso
The cameras in the familiar yellow housings use radar to detect
the speed of passing vehicles. The camera is activated when
a vehicle crosses a radar beam at excessive speed. It takes
two photographs (on 35mm colour film) of the rear of the vehicle
at an interval of 0.5secs. A series of short white lines are
painted on the surface of the road five feet apart as an independent
way of verifying the speed reading on the film. Because two
photographs are taken of the speeding vehicle it is possible
to compare the two photographs and work out how far it has travelled
in the interval using the check marks on the road. Using a simple
formula, the viewer of the film can verify the speed given by
the camera. The secondary check marks are there to safeguard
the motorist against a faulty or false camera reading.
Truvelo and Traffiphot
These cameras, also in yellow housings, use sensors
embedded in the road to measure the speed of oncoming vehicles
and photographs the front of vehicles using 35mm colour film
(though it is also capable of photographing the rear). The system
works out how fast the vehicle is travelling according to the
information received from the loops in the ground. The vehicle
speed is calculated the moment the front axle crosses the last
loop but a photograph is only taken when the camera expects
the vehicle to reach three marker lines 1.8m beyond this point.
The time taken to travel the 1.8m is recorded in milliseconds
on the negative alongside the speed. An operator also checks
the photograph manually to ensure the vehicle has reached the
marker lines as expected by the camera.
Mobile cameras are also used to supplement our fixed safety
camera sites.
|
 |
|
Lastec 20/20
These cameras employ laser technology. When the camera
trigger is squeezed, it emits a rapid stream of laser beams
that reflect off the target vehicle and record their speed in
a fraction of a second - less than the blink of an eye. These
cameras carry out a self-checking procedure when they are switched
on and the operator also carries out an alignment and distance
check.
Mobile cameras are also used to supplement our fixed safety
camera sites.
 |
|
Red light cameras
Red light cameras are designed to prevent drivers 'jumping
the lights' at busy road junctions, putting lives at risk. Loops
that detect vehicle movement are embedded in the road surface
at the junction. These are attached directly to the camera so
if a vehicle crosses the solid white line when the traffic lights
are at red, it will automatically take two photographs 0.5 seconds
apart. Two photographs are taken to prove that the vehicle has
continued through the junction and therefore not just crossed
the line and stopped. The photographs will show the time, date,
speed (not for enforcement), amber time and the time that the
traffic lights were on red. It will also show the traffic lights
and all the vehicle details. The camera can cover two lanes
and the photograph will show which lane/vehicle has activated
the system. Red-light cameras also use cassettes of 35mm film.
SPECS cameras used in road works
SPECS is a digital safety camera system which calculates
a vehicle's average speed from the time it takes to pass between
pairs of safety cameras, which can be up to six miles apart.
To avoid prosecution, drivers must observe the speed limit throughout
the enforcement route, not just at the camera sites. SPECS removes
the risk from drivers who brake hard at fixed camera sites and
then accelerate once they have passed the camera. As SPECS is
not reliant on the use of flash photograph, drivers who break
the speed limit will not see the customary flash from the cameras.
The cameras are, however, bright yellow.
Every type of enforcement system is checked to ensure it is
working properly every time it is used. The cameras are returned
to the manufacturer every year for a full calibration. When
the camera and film are removed at the end of each period of
enforcement, the camera is checked again to ensure that it has
been working properly. Furthermore, every single photograph
is subsequently checked again by an operator.
The calibration and checking regime is rigorous
to ensure that no innocent motorists are accidentally issued
a ticket.
Below is one example from each type of camera:
Truvelo
Serial
no. 869
Gatso
Serial
no. 1044/3885
Traffiphot
Serial
no. 48015
Mobile
Serial
no. 014204/448170
Certificates of Competence
To view examples of certificates of competence,
awarded to safety camera operators once they have successfully
completed a course of instruction in the use of various safety
camera systems, please click on the following links:
Example
1
Example
2
Example
3
Example
4 |
