Road Safety News

Leading analyst says speed camera report shows “clear bias”

Tuesday 20th November 2012

A leading road safety data analyst has criticised a new report into the effectiveness of speed cameras for showing a “lack of independence” and a “clear bias against speed enforcement”.

The remarks were made by Richard Owen, operations director at Road Safety Analysis, in response to a report published by Dave Finney, an electronics engineer, whom he describes as “a long time anti speed camera campaigner”.

Mr Finney’s report investigates the effect that mobile speed cameras had on the number and severity of collisions and casualties at sites in Thames Valley (Oxfordshire, Buckinghamshire and Berkshire).

Mr Finney claims that this is the first speed camera report to contain measurements of the "regression to the mean" effect at speed camera sites.

In the report, Mr Finney says: “The entire KSI casualty reduction that occurred at the mobile speed camera sites was due to regression to the mean, with the mobile cameras having provided no benefit whatsoever.”

He concludes that: “The evidence suggests that the policy of using mobile speed cameras has contributed to more collisions, more serious injuries and more deaths.

“The decision not to perform scientific trials, and the subsequent failure of official reports to demonstrate that they have completely excluded the effects of regression to the mean from their results, has resulted in there not being any good quality evidence that speed cameras have produced a positive benefit for road safety.”

In response, Richard Owen said: “I find Mr Finney’s research of interest as the data being used was provided by the Thames Valley Safer Roads Partnership (TVSRP) while I was the operations manager in charge of day-to-day running of the partnership.

“Mr Finney and I have had many long conversations about the analysis of camera statistics over the years and I have voiced concerns about the methods he has used in the past.

“In order to inform the road safety community about the validity of this new research I have prepared a summary of his latest report.

“Truly independent analysis requires the forming of a hypothesis, devising the methodology and then analysing the results. By adapting a theory to match the results Mr Finney has shown a lack of an independent approach and demonstrates clear bias against speed enforcement.

“Independent analysis of published statistics is to be welcomed and Mr Finney’s perseverance is to be commended. It is unfortunate that in his pursuit of ‘the truth’ he has followed a path that leads to an analytical cul-de-sac with the only option to turn back and start again.

“There are many published reports into the effectiveness of speed camera enforcement and Mr Finney would do well to study these, their methodologies and analytical techniques, before re-attempting to analyse the Thames Valley dataset.”

Click here to download the report, or contact Dave Finney on 07561 197 543 for more information.

Click here to download Richard Owen’s summary of the report, or contact him on 01295 731815 or by email for more information.


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"I took the view that in some way they all [road safety initiatives] must play a part, no matter how small. Everything is flawed to some degree, but sometimes you have to look at the bigger picture.

The point is that all initiatives must provide a net benefit. If, for a particular intervention, that cannot be proved or convincingly demonstrated, and there is a body of counter-evidence and strong challenges, then that intervention should be discontinued.
In the case of speed cameras, there is no evidence that they provide a net positive road safety benefit. That is why engineers such as Dave Finney and I will continue to expose the damage they do.
Eric Bridgstock, Independent Road Safety Research

Agree (6) | Disagree (9)

Yes.. but why Dave? Why do we need to “agree on a way forward”? Why do we need to “bring supporters and objectors together”?

Wearing your engineering hat, are you proposing ‘scientific trials’ on all aspects of traffic engineering and road safety or just the (one) aspects you personally don’t like?

There are aspects of traffic engineering and road safety initiatives I’ve been involved with that I’ve not been convinced about, but I certainly didn’t waste my time (paid or otherwise) trying to discredit them. I took the view that in some way they all must play a part, no matter how small.

Everything is flawed to some degree, but sometimes you have to look at the bigger picture.
Hugh Jones, Cheshire

Agree (7) | Disagree (9)

There clearly does appear to be a need. For years the authorities have publicised claims of large reductions in KSI at speed camera sites but, as figure 8.1 (above) shows, the mobile speed cameras cannot have produced any of that reduction because all of it had already occurred a full year before the speed cameras started operating.

Speed cameras are a very divisive issue and large numbers of people don't believe the claims of the authorities. This damages good work performed elsewhere in road safety. The constant debate over the issue of speed cameras strongly suggests we need to bring supporters and objectors together to find common ground on which to agree.

Perhaps surprisingly, both supporters and objectors of speed cameras appear opposed to running scientific trials. If we genuinely wish to save lives and prevent serious injuries, both sides need to agree on a way forward. I suggest running scientific trials.
Dave Finney - Slough

Agree (9) | Disagree (9)

Probably not, because there isn't any need to.
Hugh Jones, Cheshire

Agree (7) | Disagree (7)

You are right, Hugh, that law enforcement brings about many benefits for society (otherwise we wouldn't have it), such as enforcement of seatbelt and drink driving laws, but not all enforcement produces positive benefits. The authorities state that people should only be prosecuted when “in the public interest”, thereby recognising that strict enforcement can have undesirable consequences.

I understand that Police officers might view law enforcement as an absolute benefit without drawback but, as an engineer, I am more interested in the actual effects of interventions. If interventions result in more people being killed or seriously injured, we need to know so that policies can be based on evidence rather than good intentions.

Scientific trials would give us the most reliable evidence and I really cannot see, from an engineering perspective, why there is such opposition to them. Are there any road safety engineers out there who would like to get the ball rolling?
Dave Finney - Slough

Agree (11) | Disagree (12)

Without needing to apply any scientific trials or safety engineering analysis, my own common sense, years of observation of driver behaviour and attitudes tell me that there are countless accidents that have NOT happened as a result of those who would have been the cause – the reckless and the careless - having either been taken off the road and out of harm’s way through a ban or, had modified their behaviour behind the wheel, all as a result of having been “caught” and/or prosecuted for a driving offence - which in this context obviously would include speeding.

The benefit of enforcing traffic laws cannot be easily measured but that doesn’t mean it shouldn’t be done. Anti-social drivers and poor standards of driving can be addressed through enforcement without it necessarily showing up in any stats.

Anyone without a hidden agenda, with a genuine concern over road safety should see this.
Hugh Jones, Cheshire

Agree (7) | Disagree (8)

As a safety engineer, I do not work with "belief", I look for evidence and argument. There is none for speed cameras that withstands the mildest scrutiny. As before, find ANY casualty where it could credibly be argued that it would not have happened had a speed camera had previously been installed and I'll agree that they can be a road safety asset. (Just noticed that I slipped into "belief" speak previously!)
Eric Bridgstock, Independent Road Safety Research, St Albans

Agree (7) | Disagree (14)

Like all safety devices, speed cameras will have both positive benefits and negative side effects so speed cameras will prevent some collisions, while contributing to others. Therefore I can see that Hugh, Mike and Eric are all correct but the question for me as an engineer is: “How can the overall effect of speed cameras be measured?”

The largest government report (the four year evaluation) estimates RTM to be larger than all other effects combined at speed camera sites for KSI collisions and the RAC foundation report also indicates RTM to be the largest factor. Therefore RTM won't be an obscure effect, it should stand out clear as day and it does in Figure 8.1 (above).

In Figure 8.1 we can actually see, possibly for the first time, the effects of RTM at speed camera sites.

In order to ensure that interventions really do save lives and reduce serious injuries, surely we must start using scientific trials?
Dave Finney - Slough

Agree (12) | Disagree (12)

With all due respect, I don't think you have ever wanted to believe that they are a road safety asset.
Hugh Jones, Cheshire

Agree (8) | Disagree (8)

As always, find ANY casualty where it could credibly be argued that it would not have happened had a speed camera had previously been installed and I'll believe that they are a road safety asset.

Until then, people like you will continue to refer to them with phrases such as "speed cameras play a part in trying to curtail" - not the language of someone who really believes they are a force for good, capable of slashing accidents by 60% (as if often spuriously claimed).

My blinkers came off five years ago when I started investigating speed cameras and other interventions. Every week since then I have found another reason why they should be removed from our roads.
Eric Bridgstock, Independent Road Safety Research

Agree (8) | Disagree (17)

Yes, we do need to consider “negative effects”. Do you think a “negative effect” could also be that experienced by someone whose body has been broken beyond belief by a careless/reckless motorist whose behaviour behind the wheel, speed cameras play a part in trying to curtail? Take the blinkers off and look at the wider picture.
Hugh Jones, Cheshire

Agree (10) | Disagree (11)

The Figure of 5 deaths attributed to cameras comes up regularly, I would be interested to know how these occurred if you can point me in the right direction. I don't wish to sound facetious but the only circumstance I can think of is the post snapping and the unit falling on the vehicle. Every other one has to be some form of driver error. Surely, if all the drivers concerned had been driving correctly, to the speed limit and using adequate observation skills these tragic deaths would not have happened?
Mike Wilson RSO Leics

Agree (13) | Disagree (5)

"A comprehensive appraisal of speed cameras ..." must assess ALL possible effects of those devices including the negative ones, and then prove a net benefit. Paul Smith of SafeSpeed identified 40 such effects. I know of five deaths attributable to speed cameras. None of these ever gets a mention in high profile reports which exploit long-term trends, regression to the mean, improved emergency services response, better vehicle design, engineering changes etc to claim an apparent benefit from the camera.
Until genuine benefit is proven - using trials as proposed by Dave Finney - any claim of benefit from cameras is no more than wishful thinking.
Eric Bridgstock, Independent Road Safety Research

Agree (9) | Disagree (17)

You are quite right Hugh that speed cameras are an efficient system of law enforcement and the public may support them for that reason. You are also right that the effects of speed cameras may extend over very wide areas (and even nationally) and, while these effects are measurable, they are very difficult to establish as cause and effect. I have a report on this, see

Whatever effect speed cameras have, they should be most prominent on the sections of road where they operate and that's where cause and effect can best be established. You are also right that there are a host of other influences and separating the effects of the speed cameras from all the others is not easy. Hence the need to measure the largest effects, hence my report.

But all of these issues can be neatly sidestepped simply by running scientific trials and then we would know “What difference do speed cameras make to road safety on the roads where they operate?"
Dave Finney - Slough

Agree (14) | Disagree (12)

A comprehensive appraisal of speed cameras - or any other traffic law enforcement for that matter - has to recognize the benefits of such enforcement extending way beyond the road /site where the original offence took place and this wider effect is actually immeasurable and incalculable.

Simply focusing on the stats on any road or site where a speed camera is located is pointless, as on any road, the ratio of accidents to traffic volume over a given period is almost infinitesimal and in my experience, no remedial measure, whether it be Engineering, Education or Enforcement is going to reduce them any further on that road.

Speed cameras remain a very efficient, automatic system of traffic law enforcement system – you just have to look at the wider picture.
Hugh Jones, Cheshire

Agree (14) | Disagree (11)

Mr Owen says "There are many published reports into the effectiveness of speed camera enforcement". Elsewhere he rightly asserts the need for independence.

I have yet to find any report claiming effectiveness of speed cameras, which has not been prepared by or funded by an organisation or individual with a vested commercial interest in their continued deployment.

I believe Mr Finney is entirely free of vested interest - like me, his motives are improving road safety and honesty and integrity in assessment of the effects of interventions.
Eric Bridgstock, Independent Road Safety Research

Agree (15) | Disagree (11)

Anyone can see that the 'safety camera partnerships' operate on an entirely flawed basis and all reports of their 'success' are based up RTM.
Andy, Manchester

Agree (16) | Disagree (19)

As Mr Finney says, and is widely acknowledged other than those who wish to ignore the evidence, the previously reported studies of speed cameras show all of the common failings in scientific method. In essence there have been no double-blind, unbiased trials of speed cameras. Why not? Because the proponents of speed cameras don't want to hear the truth.
Roger Lawson, London

Agree (20) | Disagree (19)

I would like to thank Mr Owen for supplying the database of collisions at speed camera sites and this now allows agreement on the basic evidence.

Mr Owen is correct to state “... not all of the mobile camera sites ... were installed on the basis of high collision rates.” and that “Often there were no recorded collisions prior to installation ...”.

Of the 75 mobile speed camera sites, 12 had no collisions in the identified SSP prior to speed cameras. Clearly collisions could only go one way (up) and they did. There were 14 collisions in the first 3 years of mobile speed camera operations at these 12 sites. This increase would not necessarily be due to the speed cameras though because an increase would be expected due to RTM.

One fact my report does make clear is that the 42% KSI reduction at these sites did not occur after mobile speed cameras were deployed, the entire reduction (and more) had already occurred a full year before the mobile speed cameras started operating.

I have never actually campaigned against speed cameras, what I have campaigned for is honesty regarding their effects on road safety and for proper testing (scientific trials).
Dave Finney - Slough

Agree (22) | Disagree (11)