Nothing is that straightforward, Johann - the case of speed cameras

As ever with reporting on research we can be easily lulled into accepting the headline figures and the results that appear always to substantiate the view of authority. So it is with speed cameras. Here’s the oft wrong, Johann Hari on the subject:

We have the independent academic studies. We have reams of them. They all say the same. To cite the most detailed: a four year on-the-ground scientific study by University College London* found that when you set up a speed camera, the number of people killed in that place falls by 17 percent, over and above the general decline in road accidents that is happening everywhere because of improving technologies like airbags. That’s 100 people saved from death every year nationwide, the equivalent of stopping two 7/7s, or six Dunblaine (sic) massacres. Oh, and over 4000 people saved from serious injury.

Case closed says our friendly left-wing journalist. You lot – you speeding, middle-class drivers, you budding Clarksons – you are in the wrong. Speed cameras are saving the lives of countless kiddies and grannies across the length and breadth of England. Or is this actually the case?

Well maybe not.

There are many possible reasons which may contribute to the recent large reductions in fatalities. The economic downturn and falling traffic levels for the last two years have played a part. Similar large falls in fatalities were seen in the recession in the early 1990s.

We should also note that there has been no observable change in the long-term trend of reducing pedestrian casualties. If speed cameras were so effective then we would expect to have seen an accelerating rate of decline. Especially given that many cameras are installed with the express intention of reducing pedestrian casualty risk.

The big contribution to the decline in casualty rates is in the numbers of 16-25 year olds killed:

The number of fatalities in accidents involving young car drivers fell by 11 per cent from 635 in 2008 to 564 in 2009 – a reduction of 71 deaths, out of a total fall of 316 road deaths between 2008 and 2009. This follows a 22 per cent fall between 2007 and 2008 – a reduction of 182 deaths.

All this comes from Department of Transport figures and studies – the same studies that report every year how the main contributor to road casualties is sloppy behaviour:

The contributory factor category driver/rider error or reaction was the most frequently reported category, involved in 69 per cent of all accidents reported to the police. It was the most frequently reported category for each severity of accident

And for pedestrians:

Pedestrian failed to look properly was reported in 58 per cent of accidents in which a pedestrian was injured or killed, and pedestrian careless, reckless or in a hurry was reported in 23 per cent. Eighteen per cent of pedestrian casualties had both of these factors reported.

It may be that speed cameras save lives. But the UCL research – for all its significance (and we’ll ignore that it was paid for by the advocates of speed cameras shall we?) focuses on point studies. And even at the most dangerous point in the country the numbers of injury accidents is too small for any trend not to be meaningless.

If we’re looking for causal factors in all this – for the thing that is causing the most accidents – then we must look at the numbers or men under 30 driving on our roads. For it is these young men who are most likely to cause and to be involved in serious accidents. If Johann Hari really cares so deeply about road safety that he thinks freedoms can be infringed – then he should be advocating banning young men from driving.


*See Mr Hari, it’s not hard to find the link to the research you reference and put it in your blog post. And save us folk half an hour or so trying to find it.

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