Do speed cameras reduce accident numbers?

The Association of British Drivers (ABD) have their doubts and the figures to prove it. This is the first article from July:

'Lancashire has been one of the first counties to publish its speed camera statistics under new government rules and locals are horrified.

The Lancashire Evening Post has found three speed cameras in Preston alone where the number of accidents and casualties has increased since the cameras were installed (countywide analysis may reveal more).

According to the Evening Post those same three cameras raked in £18,000 in fines from motorists in 2010. 1

ABD chairman Brian Gregory commented.

“Not only is it scandalous that cameras where casualties have increased have been kept in operation for many years, it is even more disturbing that the authorities have hidden this data and authorised continued operation whilst being in possession of this knowledge. The government should get a grip and insist that those responsible for such malpractice in all regions are removed from public service with immediate effect.”'

 You might be even more interested in this pdf of a report entitled 'A Review of the Effectiveness of Speed Cameras'. Here's the Preface:

'A careful examination of the RAC Foundation report entitled “The Effectiveness of Speed Cameras”, authored by Professor Richard Allsop, by the Association of British Drivers has identified some questionable methodological procedures, defective analyses and significant omissions. In our view these severely
compromise the validity of its conclusions and recommendations.

The excessive reliance on speed cameras in the UK over the last two decades has affected road safety adversely. A massive diversion of resources towards speed enforcement and away from more cost-effective alternatives has regrettably resulted. This process has primarily been driven - and supported - by
the financial interests of the equipment manufacturers and of the safety camera partnerships, rather than by concerns for improvement in UK road safety.

Speed cameras are far less effective than Prof. Allsop’s paper claims. They are also far less cost effective than other available devices. Resources misdirected on speed camera enforcement would, in our view, have resulted in far greater road casualty reductions - and particularly in the KSI (Killed and Seriously
Injured) figures - had they been employed on alternative road safety measures.

Independent evidence shows that Vehicle Activated Signs are 50 times more cost effective than speed cameras; yet the proponents of speed cameras continue to argue for their use. It is in the public interest to correct any misapprehensions which may have been created by the widely distributed, but
potentially misleading, Allsop paper.

We therefore commissioned the attached report which has been produced by a suitably-qualified ABD member. It has been peer-reviewed by a number of other senior ABD members; and by other, wholly independent researchers with an interest in this topic. We believe that it addresses all the key points.
Despite their complexities, we hope that you will read both studies and so identify for yourself the shortcomings in the Allsop paper. These are sufficient in number to seriously compromise many of its conclusions regarding the effectiveness of speed cameras as a road safety tool.'