Popular Science News – Speed Cameras Reduce Accidents.
This article is not just about the evidence that speed cameras reduce road traffic accidents, it’s about whether research evidence confirms this. My intention is to publish a series of articles from the Cochrane Collaboration, considered to be the gold standard for research. One of the aims of this organisation is to collect all the eligible research on a topic and report the findings of the combined research, not just one set of research. Stay with me on this, it’s important and I’ll tell you why.
Let’s say there are only two research projects investigating whether buying property in north Cyprus is safe. One project is run by a north Cyprus Estate Agent and questions 10 of their customers, finding that 100% of those surveyed are happy with their purchase. The second is run by NCFP and questions 600 readers who have bought properties here. That survey finds that only 30% are happy. Well, guess what, the Estate Agent produces a press release saying that research shows that 100% of those surveyed were happy with their purchase, and they aren’t lying. What the Cochrane Collaboration does is adds all the eligible projects together and reports the findings from this combination of data. There’s more to it than that, including showing that the Estate Agents small sample makes it unreliable, as NCFP readership profile would too. Neither would be eligible to be included in a Cochrane Collaboration project.
Anyway, back to speed cameras:
Background
It is estimated that by 2020, road traffic crashes will have moved from ninth to third in the world ranking of burden of disease, as measured in disability adjusted life years. The prevention of road traffic injuries is of global public health importance. Measures aimed at reducing traffic speed are considered essential to preventing road injuries; the use of speed cameras is one such measure.
Thirty five studies met the inclusion criteria. Compared with controls, the relative reduction in average speed ranged from 1% to 15% and the reduction in proportion of vehicles speeding ranged from 14% to 65%. In the vicinity of camera sites, the pre/post reductions ranged from 8% to 49% for all crashes and 11% to 44% for fatal and serious injury crashes. Compared with controls, the relative improvement in pre/post injury crash proportions ranged from 8% to 50%.
Despite the methodological limitations and the variability in degree of signal to noise effect, the consistency of reported reductions in speed and crash outcomes across all studies show that speed cameras are a worthwhile intervention for reducing the number of road traffic injuries and deaths. However, whilst the the evidence base clearly demonstrates a positive direction in the effect, an overall magnitude of this effect is currently not deducible due to heterogeneity and lack of methodological rigour. More studies of a scientifically rigorous and homogenous nature are necessary, to provide the answer to the magnitude of effect. [Cochrane Summary]
So, yes, speed cameras save lives but the research is so poor in some cases that it is not clear how many lives are being saved and by what particular speed camera method. Cochrane Collaboration are asking for more scientific studies to be launched which can give a better idea about how effective speed cameras are. This is important if you have a budget and you want to know which measures would be the best to invest this in. For example, do you have an expensive automatic speed sign which flashes if you are speeding as you approach it or do you save money by just showing that a speed camera is installed? Better research would test a multitude of ideas and help decide which is best. This would not only save lives, it would save money.
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