Stats19 data does NOT understate speeding

Whether speed camera advocates seeking to explain how cameras can cut far more accidents than ever involve speeding in the first place, the authors of the Intelligent Speed Adaptation system seeking to justify their predictions of similarly large benefits, or those whose careers or reputations might suffer from exposure of their claims as blatant nonsense, those with vested interests in exaggerating the significance of speeding in causing accidents claim from time to time that police officers routinely fail to tick the “speeding” box unless they feel confident enough for their assessment to stand up in court.

When I again became irritated by such claims I sent a Freedom of Information request to every police force in the country asking for any documented evidence of discrepancies having been found between Stats19 forms having failed to identify speeding as a “likely” or “possible” contributory factor and later more detailed “data quality” audits and the more detailed investigations which follow more serious accidents.

The great majority who have now replied have provided completely consistent answers – so much so that there is little point in my spending time to tabulate them as I had intended, but I would be happy to copy all of the email replies to anyone who wishes to see them. In summary:

Not one Police Force across the country has even a single documented example of a Stats19 form failing to identify speeding as a “likely” or “possible” contributory factor to an accident involving any one of the three degrees of injury severity.

This does not of course mean that it has never happened, and not been spotted, but it surely does mean that it does not happen to any statistically meaningful extent.

One reply confirmed in any case that Stats19 forms are never used in court cases (which as I had pointed out, necessarily rely on more detailed evidence of speeding than could ever be provided by a tick on a form, devoid of any indication of the extent of speeding involved, and qualified as being either “likely” or “possible”. The only way Stats19 forms are involved is when copied to the Defence in a bundle of “Unused” information.

It is also important to remember that the contributory factors analysis published annually by the DfT (5% of Slight, 6% of All, 9% of Serious Injuries, 10% of KSI and 15% of Fatal accidents respectively) include (a) “likely” (b) “possible” and (c) non-primary contributions, and therefore that they inherently overstate the true significance of speeding, not understate it as camera advocates claim.

Add to that the plain fact that speed camera sites cover only 3% of urban and 1% of other roads, the possible contribution of speed cameras to accident reduction is vanishingly small.

On the other hand, close to 40 known adverse effects of cameras, from sudden braking to distraction to bunching to more, more dangerous overtaking, many of which apply everywhere all the time, might well cause more accidents than speed cameras could ever eliminate.

* see  E.21 to E.24  on ,   Speed Camera Damage to road safety 03a1c9  and   Speed Camera Damage Update



Comments are closed.