Do All Speed Cameras Work the Same Way?

It has been more than 30 years since Britain's first speed camera was switched on over Twickenham Bridge in Surrey. Since the creation of the Gatso camera in 1992, these devices have earned millions in revenue; but can they be relied on to reduce driver speed and capture reckless road users, or are they simply a way to bring in money through speeding fines?

Reports vary as to how many speed cameras there are in the UK, but the government believes they are a vital part of its effort to reduce road traffic accidents. Research has supported this, with a 2017 study estimating that, between 1992 and 2016, speed cameras in the UK reduced fatalities by up to 68% (within 500 metres of the camera). It also estimated that adding another 1,000 cameras to accident hotspots could save up to 190 lives and prevent up to 330 serious injuries each year.

However, the use of speed cameras has changed significantly since then. Not all speed cameras work the same way, but there is a lack of data about the impact of these differences and newer technologies like average speed cameras, mobile speed cameras, and others. This lack of data and variable approach makes it much more difficult to establish whether or not speed cameras are working as intended.

Further, there are many people who beg to differ with the government, including the very man who helped create the speed camera. Roger Reynolds stated in 2012 that the use of speed cameras had been "a fiasco" and said in 2015 that enforcement agencies are now too strict on minor offenders. With the number of caught motorists reaching 1.74 million in 2022, Reynolds may not be far wrong - so are speed cameras still a useful tool or are they becoming an overused nuisance?

How Do Speed Cameras Work?

There are several types of speed cameras in the UK, but the two most common are the average speed camera and the fixed speed camera. Regular motorists may be familiar with the SPECS average speed camera, which utilises state-of-the-art video with automatic number plate-reading digital technology. As vehicles pass between the entry and exit camera points, their number plates are digitally recorded. The images are then paired up and the computer works out the average speed between the cameras based on the date and time stamp of each image.

A group of these cameras is often linked together to capture a vehicle's speed over a longer distance, and calculate an average speed based on this data so as to catch speeding drivers. They are often located either end of a road where a lower speed limit applies - for example, a road that passes through a village - to catch drivers who exceed the speed limit at any point on this journey. These average speed cameras may be placed at regular intervals along motorways but are not the same as motorway speed cameras. They may not be clearly indicated, unlike the bright yellow fixed speed cameras drivers commonly see. Another clear way to tell is that fixed speed cameras flash when they capture an image, but average speed cameras do not. 

Fixed cameras (including the Gatso speed cameras mentioned above) are placed along roadsides where there is a high risk of accidents, according to local data. They work by taking two photographs in quick succession of each vehicle that passes - then, they compare the position of the vehicle and the time between the images to calculate the speed of the car. Fixed speed cameras are very visible and heavily signposted to act as a deterrent. In some areas, it does not matter whether these speed cameras work, because drivers will slow down anyway to avoid being caught.

A third common type is mobile speed cameras, which work in a very different way. These devices are operated by police officers from their vehicles, which means that they can be positioned anywhere that it is safe to park a car - or, in some cases, be used in moving vehicles. Mobile speed cameras work using radar technology, or lasers, and have a range of up to a mile. Provided the operator can see your vehicle with their radar or laser gun, they can obtain an accurate measurement of the speed at which you are driving.

JMW has produced a guide to how different speed cameras work which aims to dispel speed camera myths and explain how different types of speed cameras catch speeding motorists on UK roads.

Are Speed Cameras Always Correct?

The original Gatso speed camera detectors do not always work successfully. They may flash on their own without being properly triggered by a speeding vehicle, or be set off by vehicles travelling in the opposite direction.

The photos are only used to perform a secondary check of the alleged speed as the driver's speed is determined in relation to markings on the road. However, digital SPECS average speed cameras are proven to be far more reliable as there is no film, and your speed is calculated by time rather than markings on the road.

The latest technology has made this process even more precise, and while it is still possible for cameras to make mistakes, it happens much less often. Average speed cameras work using infra-red light to capture licence plate information, which means that they work in the dark and in bad weather conditions without needing to use a flash, and their results are very reliable.

How Much Margin for Error Is There?

The National Police Chiefs' Council recommends that police forces grant leeway to drivers travelling over the limit at a rate of 10% of the limit plus two miles per hour. However, this leeway is discretionary, and does not need to be applied to all cases consistently. According to the law, even one mph over the limit can result in a speeding ticket or other penalty.

Police forces should take into account a variety of factors, including the fact that speedometers are not always calibrated properly and may not be a true reflection of the speed at which the vehicle is actually moving. If you believe that a speed camera gave incorrect evidence, there may be scope to challenge a charge on this basis.

What Happens if I Am Caught Speeding?

The penalties for speeding are not usually severe, but you can receive a fine and penalty points on your licence. If you already have points on your licence - and especially if you passed your driving test within the last two years - you could face more serious consequences, including a driving ban or the revocation of your licence. In the latter cases, drivers must pass both their theory and practical tests again before they can legally drive, so it is vital to avoid this outcome.

In most cases, the first indication that you have been caught speeding is the receipt of a Notice of Intended Prosecution (NIP). For an enforcement authority to prosecute you for speeding, they must send a NIP to the registered keeper of the vehicle involved in the incident within 14 days of the alleged offence. However, if you are pulled over by an officer, and issued an ‘on the spot’ speeding ticket, the 14-day rule does not apply.

An NIP does not mean that you will definitely be prosecuted - it only asks for information about who was driving at the time of the offence and allows for the police to prosecute if they wish. If the registered keeper was not driving the vehicle at the time, they must identify the driver. If you are unable to provide details of who was driving, you may receive a separate charge of failing to provide information, which can result in a penalty of six points on your driving licence and a fine up to £1,000. When you receive an NIP, you are legally required to provide the requested information within 28 days.

If you are caught by a police officer or other traffic officer using a handheld or mobile speed camera, they may issue you with a verbal warning, NIP in the post, or a fixed penalty notice on the spot.

After responding to the NIP, there are several potential outcomes. If the police decide to prosecute, you may receive a fixed penalty notice, which typically includes a fine and penalty points on your driving licence. Alternatively, you may be given the option to attend a speed awareness course. Local councils can decide how best to tackle specific problems in their areas, and one approach is to offer first-time offenders a speed awareness course instead of three penalty points on their licence. This will usually only apply to those caught marginally over the speed limit and are at the discretion of the police force. You may need to pay to attend the course, but this avoids incurring any penalty points.

If the speeding offence is not your first offence, is severe, or if the driver has accumulated a significant number of penalty points, they may receive a court summons. In this case, the driver will need to attend a court hearing and may receive a much more serious penalty if they are found guilty.

Can I Defend Myself Against Prosecution?

If you receive a NIP and are facing prosecution for a speeding offence, it may be worthwhile to seek legal advice. Consult with a solicitor or legal expert specialising in motoring offences, as there are circumstances in which you may be able to defend yourself and avoid prosecution.

Seeking legal guidance is vital if you have received a court summons, as a solicitor can provide guidance on your options and help you prepare for any potential court hearings. In such cases, you should also gather any evidence that may support your case. This could include photographs, dashcam footage, or witness statements. This evidence may be useful in contesting the alleged offence or mitigating the penalties. If you are unsure about how to do this, your solicitor can help.

The best way to avoid prosecution is to abide by the law at all times, and this includes by driving at or below the speed limit. Make sure you stay aware of the relevant speed limit wherever you drive and remember that GPS devices may give you incorrect information, which is not a defence in law. If in doubt, follow the speed limit as indicated by signs on the road.