Technical Report No.3.
 Fixed Speed Cameras
Radar or Non Radar, fact and fiction.
By now, most of you will be aware of the installation of the, fixed, pole-mounted speed cameras. With much confusion about the term "Speed Camera" The following information is intended to confirm, in some cases, or to enlighten those not so aware, of the method of operation of these cameras.
Original article copyright Clearway Ltd 1995.

Pole mounted speed cameras, do not operate by Radar or Laser and, therefore, radar detectors will not alert you to their presence, as these cameras do not send out a radio signal that can be detected.

The cameras can operate with or without a flash. They are either Wet film or Digital storage, that allows operation in all light conditions without a flash. The flash will only operate under low light conditions. The latest Digital CCD systems use Infra Red flash. Therefore the absence of a flash, does not mean the camera is not taking pictures.

The latest digital (non wet film) cameras, store images on digital media for collection or transmission to a central processing station.

The speed camera measures the speed of passing vehicles by a "Timing process" or Amphometer (strips across road). There are two piezo sensors or strips of rubber pressure hose installed in the road a set distance apart (900-4000 mm apart, dependant on timing configuration).

It does not operate by proximity loop in the road, like traffic lights! Pulses are generated as each tyre passes over the 2 or 3 timing strips. Vehicle average speed and length (wheelbase) is calcualted, to determine when camera should activate.

As a vehicle crosses the first strip in the road it starts the clock, which is stopped when the second strip is crossed.
The time and distance is then converted into an average speed calculation. If that speed is above the preset limit a photo is taken with time, date and speed recorded.
This principle for speed measurement has been used for over 30 years all around the world. This method of speed detection Time over Distance, is more accurate than radar.

When first introduced into other countries in years past, these distance over time speed checking devices used two rubber strips that were moveable from site to site.
The operators would move from one location to another setting the strips up on different roads.
The rubber timing hoses were set about 900 mm apart.

Because the Amphometers were mobile, they represented a problem for many drivers.
With low cost GPS systems these days, plotting or logging the co-ordinates of fixed speed cameras into your low cost GPS has eased their surprice factor.

If you encountered one of the early rubber strip units, it was all over in seconds. By the time you heard the wump/wump as you hit the hoses, you could start taking out your licence. Drivers were usually stopped 500 metres down the road by a Police car and asked to contribute on the spot.
The greatest threat to these "Amphometers" was from trucks. As the big 18 wheelers saw the strips across the road, they would lock up the back wheels before they hit the strips, dragging them across the hoses. This converted the hoses to what appeared to be a pile of rubber spaghetti, bringing to an end that day's speed checking operation.
The truckers could see the humour. The "other guys" weren't too happy, but could do nothing.

In New Zealand the main threat to the fixed cameras are vandals. Throwing a potato sack over a camera post has occured, The odd can of spray paint has had a similar effect.
It must be noted that these pole-mounted cameras can check the speed of both approaching and receding vehicles. If there are two vehicles in the photo, it may be "no take". Always request the photo for proof.

When you are driving next, if you haven't had a close look at the markings in the road, (where the strips are implanted) stop, get out and educate yourself.

For the latest list of locations click here. :Fixed Cameras