Confusion Reigns Over Scottish Speed Camera Statistics
Recent statistics released by the Scottish government 1
appear to be confusing some journalists and campaigners who are attributing the entire 68% reduction in fatal and serious injury casualties to speed cameras.
ABD Chairman Brian Gregory comments:
“It is ludicrous to suggest that cameras are responsible for all the reductions and questionable to claim that they are responsible for any of the reduction given the way the figures have been presented. We have long called for speed camera statistics to be presented with full data but regrettably the authorities have always fought against this.”
The ABD highlights the following issues in relation to the Scottish report which it should be noted does not itself claim the reduction to be due to cameras:
- The report covers a 14 year period. During this time there have been huge advances in vehicle design, airbags and ABS brakes being but two examples of almost universal fitment. Mobile phone use will have speeded emergency response time to rural collisions cutting fatalities. Medical procedure improvements also have positive effect.
- The whole of Scotland, over the same 14 year period, has shown a KSI casualty reduction of almost 50% 2 3, due largely to the above points yet only a minute proportion of Scottish roads are covered by cameras. Camera sites would be expected to have similar reductions without a camera, more when regression to mean is taken into account.
- The report takes no account of 'regression to mean'. Put simply, cameras are almost invariably installed where there have been an unusually high number of casualty accidents over a few years. In many cases these are 'fluke' accidents and the level will naturally revert to the norm for the location with no intervention. All the Scottish statistics compare just such a period, a three year period prior to installation. 'Regression to mean' will therefore inevitably be a factor.
- The report fails to note any other changes at camera sites such as road improvements, opening of housing estates, closing of factories, bypassing of roads, erection of speed interactive signage etc. All of these inevitably have an effect. It would be a very negligent authority that just put up a camera with no other improvements.
- The report only includes cameras that were operational at the end of 2011. How many unsuccessful cameras were removed prior to this? If they are not included then the sample is selective.
Brian Gregory comments further:
“The authorities are never keen to include the full facts in their reports. Whilst the Scottish government have not claimed success for cameras, it is misleading not to point out the other factors that could easily make up the whole casualty reduction. Of course there are huge vested interests keen to prove cameras work who will jump upon any report such as this and who also wish to repress the true facts. We ask them to carefully consider that their actions can skew road safety practices. This can lead to ineffective measures taking prority over more effective measures. Anybody who misleads or skews road safety statistics ultimately has blood on their hands.”
NOTES FOR EDITORS
1. Key Scottish Safety Camera Programme Statistics, 2011
2. Road Accidents Scotland 2001
3. Key Reported Road Casualties Scotland 2011
(Total KSI in 1997 = 4002. Total KSI in 2011 = 2059)
Notes for Editors about the ABD
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