Gatso
Invented by a former rally driver, Dutch citizen Maurice Gatsonides, this is probably the one camera most people would be familiar with. It is the most common of all speed cameras in the UK, with some 4,000 Gatsos currently making up around 90% of all fixed units in the country.

The camera works by emitting radar beams to measure a vehicle's speed. If the trigger speed is broken by a speeding motorist, two photographs are taken half-a-second apart. The camera uses a powerful flash to show the rear of the vehicle, the registration plate, and the dotted lines in the road.

The cameras themselves are usually rear-facing, to stop the flash from blinding oncoming motorists.

However, it is becoming more common for cameras to be used to catch vehicles travelling in both directions, and can also be swivelled to check different sides of the road. They can also distinguish between different vehicles, so if a 40mph limit was imposed on trucks, yet cars could travel at 60mph, the camera can enforce the two separate speed limits.

The units themselves can record up to 400 pictures before the film needs to be changed. Typically, the units cost around £20,000 to install, however due to the need for a 240 volt power supply, this can cost much more in the more rural locations.

As mentioned previously, a series of dotted lines are to be found hand-in-hand with Gatso installations. These are calibration markings, and are used to back-up the Gatso's radar readings, as the photographs are the only evidence admissible in court. This is because the speed calculated by the radar is deemed to be too unreliable, as it is prone to error from simultaneous reflections, multiple vehicles etc. By counting how many lines have been passed between the flashes, the speed of the vehicle can be calculated.

Also, on the M25 in Surrey and Berkshire, Gatsos have been installed on overhead gantries, so all four lanes on the carriageway can be constantly monitored.

Truvelo
In a way more cunning than the Gatso, the Truvelo system is designed to take forward-facing (or rear-facing) photographs of a speeding vehicle, thus allowing the driver to be included in the resulting picture. This is because the camera emits an infra-red flash, rather than a conventional light bulb flash, which is invisible to the passing driver.

Two pairs of piezo-electric strips are installed into the road prior to the camera, each strip a set distance apart. The time taken for the vehicle to pass between each strip is measured to give its speed, thus the camera only needs to issue a single photograph of the vehicle. If the speed calculated by each pair of strips do not match (+/- 1mph different), the offence is rejected.

A series of narrowly-spaced lines are painted on the road in front of the camera to distinguish between the offending vehicle and any innocent vehicles that so happen to be passing at the same time. Due to their better technology, Truvelo systems are becoming more commonplace, with a number of counties (for example Northamptonshire) using this variety and no other. Also, the camera is available in two varieties, 240v mains and 12v battery. The 12v system allows the camera to be used in rural locations, thus reducing the cost of installation, and will activate the camera for 800 photographs.

Watchman
Not so common yet, as these cameras are currently on trial in North West England pending approval to be widely introduced. These cameras are rear-facing, using technology similar to the Gatso camera. However, this camera is used as a traffic calming measure rather than a speed trap. They are usually linked up to a flashing sign advising of speed limits, but are also used to monitor traffic. They do not issue fines or penalty points, but do record the vehicle's number plate, time and speed - often they are calibrated to send a signal requesting an advisory notice be automatically sent out to the driver advising them of their speeding.

Peek
Not as common as Gatsos and Truvelos, but there are still plenty of these types to be found in the UK, mostly in urban areas.

Generally, they work in the same manner as the Gatso, using radar beams and a flashing bulb for taking the photograph. Again, most are rear-facing due to the brightness of the flash.

There are also some of these cameras that have been adapted to be used as red light cameras, used in the same way as the Red Light Gatso, shown below.

SPECS
This camera system has its own feature page - please click here to take a look.

DS2 Camera
Also known as Speedmaster and Autovision, these semi-permanent cameras can detect speeding motorists travelling in both directions. They work by using piezo-electric stips in the same way as a Truvelo camera, which are hooked up to a small grey station on the roadside. When the DS2 system is in use, two tactics can be used - either a camera records the car passing through the speed trap, or the speed is recorded by the police, and another patrol further up the road receives the registration details and stops the vehicle as it passes. If the camera option is being used, it can be left unattended at the side of the road.

Mobile camera
Commonly used to catch motorists on specific roads at certain times, mobile cameras are compact and easy to move around. Generally, there are two types of mobile camera commonly used. First is the Mini-Gatso, similar to its big brother but installed onto a trailer for ease of movement. The other type of mobile camera is the 'laser gun' camera, which uses Number Plate Recognition, and can record speeds and take pictures up to one kilometre away.

Speedcurb
This type of camera has only been introduced within the past couple of years. Unlike the other cameras on this page, this system uses three separate digital cameras that are linked up to a recording station at the side of the camera. They can be used either as a speed camera, a red light camera, or even both together!

The system uses induction loops for red light monitoring and piezo-electric strips when checking vehicle speeds, with the camera having the ability to switch modes when the traffic changes from red to green (if set up to do this).