Truvelo vs Gatso

Two very popular revenue generators in use on British roads today are the Truvelo (left) and the Gatso (right) speed cameras.

Although these cameras detect speeding motorists, they do so in different ways.

Gatso
The Gatso unit is a rear-facing camera which uses RADAR to track the speed of a moving vehicle. Using the doppler effect (technical information will be added soon to explain this) , the camera can detect the exact speed of a vehicle in a split second and determine if it is exceeding the posted speed limit.

If the vehicle is exceeding the limit, the camera is triggered.

Gatso cameras can ONLY take photographs of the rear of the vehicle.

Truvelo
The Truvelo unit is a forward-facing camera which uses induction strips embedded in the road surface to measure the speed of approaching vehicles. Yards in front of the unit are three white lines pained on the road. Each line is a pressure sensor which is triggered when a vehicle moves over it.

The time taken to cross all three lines is used in the Speed = Distance / Time formula. The camera site knows the distance between the pressure sensors, it then times how long it takes the car to travel over them and works out the speed of the oncoming vehicle. If this is over the posted speed limit, the camera is triggered.

Truvelo can ONLY take photographs of the front of the vehicle.

Truvelo versus Gatso
If we look at Truvelo versus Gatso then obviously both have pros and cons. Drivers can get advanced warning of Gatso cameras using RADAR detectors. Although the new "Instant-On" Gatso cameras reduce their RADAR emissions and this makes detection harder, though not impossible. In addition to this, the secondary markers (white dashes on the road in front of the camera) are sometimes visible from a distance.

Truvelo cameras do not emit RADAR pulses, therefore cannot be detected by RADAR detectors. However, they are usually highly visible and ugly looking cameras on the roadside. An alert driver can see this and slow before reaching the camera site. The detection/induction sensors are not easily visible to the driver.

Gatso cameras will detect every motorist who speeds passed it. Truvelo cameras don't!

Vehicles with front facing number plates will certainly be photographed and the driver will be traced. There are some drivers however without front facing number plates. They're motorcyclists. These drivers can drive at any speed towards Truvelo cameras, be photographed and get away scot free and there have been many reports of motorcyclists flashing the "V sign" or waving at the cameras when photographed.

Why then, are Truvelo cameras becoming more commonplace on our roads? Isn't this discrimination between motorcycle drivers and other motorists?