Thames Valley Speed Cameras

An independent report        

INVESTIGATION INTO THE EFFECT OF SPEED CAMERAS ON ROAD SAFETY.

 

There are many opinions and a lot of statistics about speed cameras, but what effect are they actually having?

 

This website aims to answer the question: "What difference have speed cameras made to our safety when we use the roads?" and presents independent research based on data obtained from official sources such as the DfT (Department for Transport) and the camera operators. Everyone can therefore check and verify all the information for themselves.

 

Latest: new report on the Thames Valley speed cameras.

 

The investigations presented in this website lead to these recommendations:

 

  • The author considers it essential that a new national policy should be adopted to ensure that all speed cameras must only be operated within scientific trials in order to evaluate their effect on collision rates at camera sites. These trials should take the form of Randomised Controlled Trials conforming to a national standard that are rigorous, independently organised and independently supervised. This will allow all trials to be combined into a national knowledge base.

 

  • Another new policy should be adopted to ensure that area-wide effects of speed cameras are independently monitored, analysed and reported.

 

 

Why investigate?

 

When I first looked into speed cameras it was just for my own personal interest. I naturally expected to find that they did improve safety and had no idea that what I discovered would lead me to undertake such a detailed investigation. I read many of the reports written by the speed camera operators which showed that, after speed cameras were deployed, vehicle speeds were lower and there were fewer collisions of all severities. Cameras did appear to be effective except that I had one concern. While it is clear that cameras reduce the speed of traffic, I noticed that none of these reports established that it was the cameras that caused the reductions in collisions. I therefore chose a camera site at random and emailed the operators asking what caused the crashes. The answer to this prompted further investigation quickly leading to a surprising discovery. If I was to install speed cameras with the intention of preventing collisions, I would have first asked the question "how many collisions involve a vehicle that was exceeding the speed limit?". I can find no evidence that anyone involved with speed cameras thought to ask this question!

 

Exceeding the speed limit as a contributory factor in collisions (Speeding):

 

When a road traffic accident results in someone being killed or injured, the Police are tasked with investigating why each of those collisions occurred but, back in 1993 when the first speed cameras were installed, their report forms did not include "exceeding the speed limit" as one of the possible factors to be investigated. The authorities did eventually include this but not until 2005, after over a decade of speed camera operations. The Police discovered that exceeding the speed limit is a factor in fewer than 8% of all fatal or serious collisions across the whole of Great Britain, which meant that the vast majority (over 92%) of these collisions occurred when drivers were not speeding. I put together a page to include the most relevant official information I could find regarding the role that speeding plays in road safety (with reference to using speed cameras to address this) and the page includes where that information came from. Don't take anyone's word for it, check for yourself from the official government sources.

 

How to determine the effects of cameras (Scientific trials):

 

The "Randomised Controlled Trial" (RCT) is a scientific test designed to determine the effect of an intervention in a complex environment. The road network, with millions of people using it every day in many different ways, is a complex environment and a speed camera is an intervention therefore the RCT has been designed for exactly this sort of purpose. So what are the effects of cameras when these tests are performed? I was surprised to discover that no speed cameras have ever been subjected to scientific trials anywhere in the world, yet the test is simple so I wrote this page to explain it.

 

The foundation of the UK speed camera programme (The Four-year Evaluation):

 

The largest and most comprehensive government report on speed cameras published in the UK is called The Four-year Evaluation (4YE) and it states that, at the camera sites, "Overall 42% fewer people were killed or seriously injured". But here's the puzzle: how can speed cameras cause a 42% reduction when fewer than 8% of those collisions involved a vehicle that was speeding in the first place? The answer to this puzzle is actually in the report, but it is very well hidden. It turns out that the cameras did not cause the 42% reduction, that the effect of the cameras is actually very small and that they may not have saved any lives, nor prevented any serious injuries whatsoever. This is startling. The 4YE may be considered to be the foundation of the speed camera programme in Britain, yet it contains no evidence that any real benefit has been achieved. I wrote this page to explain the evidence presented in the 4YE but don't take anyone's word for it, check for yourself from the official government source.

 

The bit that confuses almost everybody, RTM (Regression to the Mean):

 

There would be no need to consider the RTM effect if scientific tests had been done but, in the absence of those tests, we need to understand and exclude RTM in order to accurately evaluate the effects of cameras. It is clear from the above government report that fatal and serious injuries would have reduced dramatically at the locations where speed cameras were deployed anyway, even if the cameras had not been used, because of the RTM effect. Collisions are basically random events so numbers of them tend to rise and fall. If a section of road had a higher than normal number of serious collisions (perhaps a spike of just 2 or 3 more unfortunate random chance incidents) in previous years, then this is unlikely to reoccur in the following years and the numbers will therefore tend to drop. This reduction is referred to as RTM and it occurs whether a speed camera is placed there or not. Therefore a fall in collisions on roads where speed cameras have been deployed tells us nothing about what effect the cameras actually had. In all the speed camera reports I have read, I have yet to find one that has successfully excluded the RTM effect from it's results, even though this is quite easy to do. I wrote a page to explain RTM, along with how to exclude it, in order to find out what effect the cameras had.

 

Road safety across the whole of Great Britain (GB road safety):

 

The speed camera programme is the largest and most expensive road safety policy ever implemented by our authorities so we might expect to have seen the largest change in road safety across the country when the programme started and as it expanded. And we do. The trend in fatalities per billion vehicle miles (probably the most important road safety indicator) clearly changed when speed cameras started to be used, but it went the wrong way. Road safety basically collapsed for the next 12 years and only started to recover in about 2007, when the economic crisis hit. This was quite a disaster but don't take anyone's word for it, check for yourself from the official government data.

 

The Royal Borough of Windsor & Maidenhead (RBW&M):

 

In 2009, councillors in RBW&M requested that I investigate the effectiveness of their speed cameras so that this could be taken into consideration at their council meeting. At this meeting, councillors were to decide whether to continue paying £200,000 per year to TVSRP (the organisation that operated the cameras) to pay for the running costs of speed enforcement at their 13 camera sites. TVSRP stated "... the casualty reduction record is impressive with a 44% drop in recorded injury collisions" so I simply plotted those collisions on a graph. I found that around half of that drop occurred 2 years before the cameras were installed, and the other half over 6 years later. Cameras aren't magic, they cannot go back in time and prevent collisions when they weren't there so they could not have caused the reduction 2 years before and, if they have failed to produce any reduction for 6 years, a reduction around 12 years after installation cannot be due to them. Further to that, the number of serious injuries went up. I could find no evidence that these cameras achieved any improvement in road safety whatsoever but don't take anyone's word for it, check for yourself from the official government data.

 

Do speed cameras prevent collisions? (Thames Valley cameras)

 

This is my first major report and it investigates the effect of speed cameras in Thames Valley on the number of collisions that resulted in death or injury. It includes all 212 fixed camera sites – within which there are 359 fixed (Gatso-type) cameras – and all 105 mobile camera sites that had been operating for two or more years at the start of 2009.

 

The report concludes that:

  • Speed cameras have not made any impact in preventing road traffic collisions.

 

  • There was no reduction in the number of collisions at fixed (Gatso) camera sites after they were installed and there was no reduction in the number of collisions at mobile camera sites after they started operating.

 

  • Even after compensating for other influences such as rising traffic volumes and safer vehicle design, the cameras are still not demonstrated to have resulted in any reduction in collision rates. In fact, collision rates increased at mobile speed camera sites following deployment relative to all roads in the Thames Valley area.

 

  • There was found to be no relationship between vehicle speeds and the number of collisions. Reductions in speeds at camera sites (both average and above the speed limit) did not result in any reduction in the number of collisions.

 

Contact me (About the author):

 

All information presented here is believed to be accurate and presented honestly. If any errors are found they will be corrected as soon as possible. Contact me here: Dave Finney.