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Road safety expert Idris Francis on the inaccurate claims by Mick Giassani, the Chief Constable of Gwent, on speed cameras

CLAIM:  "Casualties have fallen by 50% in 8 years due to speed cameras" – BBC News 9th August 2010

RESPONSE: All casualties fell from 313,046 in 2001 to 222,100 in 2009 or by 29%. Does Mr. Giassani not understand percentages? The supposed benefits of speed cameras, necesarily limited to the 6% of all accidents that involve speeding, occur only within camera sites, usually defined as about 0.5km radius or less than 3% of road surface. It is therefore literally impossible for speed cameras to have cut overall casualties even by 0.5% let alone by the fatuous claim of 50%.

Major improvements in car design (safer structures, ABS, air bags, stability systems etc) and in roads have all made major contributions to these falls, far more than speed cameras have or ever could. Slowing traffic growth rates, including unprecedented 1% falls in 2008 and 2009 have also contributed.

Serious and slight injury figures are notoriously unreliable because of low and falling reporting levels – Transcom now refuse to believe SI figures because hospital, car insurance and fire and rescue records show no such falls. The DfT now believes that the real figures are between 3 and 5 times higher than reported levels, though for obvious reasons fatalities are recorded accurately.


From 1994 to 2006, the period of increasing camera numbers, fatalities (by far the most reliable indicator) fell only twice in 12 years, an overall fall of only 13% in 12 years, a small fraction of the rate from the late 1960s to 1993 without cameras when traffic growth was higher.

It is inconceivable that speed cameras which had failed to reduce casualties over 14 years despite growing numbers could be responsible for the falls in 2007, 2008 and 2009 could then suddenly have started to become effective, just as numbers levelled off and then started to fall and just as GPS detectors reached installation levels of 50%. In any case, as above, as camera benefit is restricted to camera sites, no such marked effects on national numbers are remotely possible.

 In Mr. Giassani's home patch of Gwent, with many cameras, the 3 year rolling average of fatalities from 1999 was 26.0, 25.7,  25.7, 27.3, 24.7, 28.0, 29.3, 28.3, 26.0, 26.0, 25.0. Where is the speed camera benefit in those figures, Mr. Giassani – and does your responsibility for road safety not extend to the whole of your area rather than 3% of it?

From 1995 to 2004 Gwent SI did fall steadily from 448 to 186, although as above tbe BMJ consider the falls in that period to have been due entirely to falling reporting levels. Since then the figures were 210, 173, 203, 202 and 141 in 2009, albeit in the worst recession in living memory. If cameras were so effective what happened from 2004 to 2008?

CLAIM: "Casualties will rise unless other methods replace cameras" (BBC News 9th August 2010.)

RESPONSE: I have repeatedly emailed every police force and camera partnership in the country, including Gwent, for more than 3 years, pointing out that vehicle activated signs are massively more cost effective than speed cameras. Former Roads Minister Stephen Ladyman's letter to Transcom admis that far from being 12% more cost effective than vehicle activated signs, speed cameras are some 900% less cost effective.

Safe Speed provides the detailed documentation showing how the DfT deliberately misrepresented the data
and then used incorrect analysis to conjure up a 12% advantaged for cameras when the reality was that, sensibly costed over 10 years and not one, signs provide 50 times the benefit for the same expenditure.

19 comments for: Fisking the Chief Constable of Gwent

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