Last month I blogged about an experiment in Sweden where a speed camera records all the cars keeping to the speed limit with all the legal drivers going into a prize draw for cash prizes. The trial has now been carried out and here’s the result (quick version – the average speed of traffic fell from 32 km/hour before the trail to 25 km/hour during the trial):
Welcome to another in my occasional series on useful, interesting or controversial findings from academic studies. Today’s it is the question of speed cameras, for which a study of international evidence has recently been conducted:
To evaluate the effectiveness of speed cameras, the authors examined all eligible studies, that is, studies that met pre-set standard criteria. We analysed the effect of speed cameras on speeding, road traffic crashes, injuries and deaths by comparing what was happening in road areas before the introduction of speed cameras and after their introduction, and also by analysing what was happening in comparable road areas where no speed cameras were introduced during the study period.
The authors accepted a total of 35 studies for review which met the pre-set criteria. All studies reporting speed outcomes reported a reduction in average speeds post intervention with speed cameras. Speed was also reported as either reductions in the percentage of speeding vehicles (drivers), as percentage speeding reductions over various speed limits, or as reductions in percentages of top end speeders. A reduction in the proportion of speeding vehicles (drivers) over the accepted posted speed limit, ranged from 8% to 70% with most countries reporting reductions in the 10 to 35% range.
Twenty eight studies measured the effect on crashes. All 28 studies found a lower number of crashes in the speed camera areas after implementation of the program. In the vicinity of camera sites, the reductions ranged from 8% to 49% for all crashes, with reductions for most studies in the 14% to 25% range. For injury crashes the decrease ranged between 8% to 50% and for crashes resulting in fatalities or serious injuries the reductions were in the range of 11% to 44%. Effects over wider areas showed reductions for all crashes ranging from 9% to 35%, with most studies reporting reductions in the 11% to to 27% range. For crashes resulting in death or serious injury reductions ranged from 17% to 58%, with most studies reporting this result in the 30% to 40% reduction range. The studies of longer duration showed that these positive trends were either maintained or improved with time.
The quality of the included studies in this review was judged as being of overall moderate quality at best, however, the consistency of reported positive reductions in speed and crash results across all studies show that speed cameras are a worthwhile intervention for reducing the number of road traffic injuries and deaths.
To affirm this finding, higher quality studies, using well designed controlled trials where possible, and studies conducted over adequate length of time (including lengthy follow-up periods) with sufficient data collection points, both before and after the implementation of speed cameras, are needed.
Carrot or stick? It’s a common policy debate – do you get the best outcome by punishing or encouraging?
At the moment, it most frequently comes up in political debates over the environment, and in particular recycling. Can recycling levels best be raised by encouragement, such as discounts for recycling more of your waste, or by threats, such as legal limits on how much you can place in your bins?
It is a question that can be applied much more widely, which is why I was interested …
The BBC is keenly promoting a story about speed cameras.
The cameras have been switched off in Oxfordshire: they still measure the speed of passing motorists, but no longer take pictures. Motorists can therefore speed with impunity and remain point-less.
London Assembly Member Richard Tracey has past form on writing odd letters to local newspapers in London. In August I reported on his claims that a Tory mayor and Tory boroughs were responsible for London not seeing a rise in unemployment – when in fact unemployment, sadly, has soared across the whole of London.
Now he has sent this letter to Southwark News:
“The introduction of speed cameras to enforce 20mph zones in Southwark, Waltham Forest and other London boroughs is bad for London’s hard-pressed motorists.
There are already too many revenue-raising speed cameras on the capital’s roads, London does not need more.
Furthermore, there is a danger that large areas of average speed-check cameras will encourage drivers to concentrate on their speedometers instead of the road; which would have a counter-productive effect on safety.
Many road-users feel that congestion means journeys in London already take too long and 20mph speed limits will force people to spend even longer in their cars. Not to mention that driving at 20mph causes even more pollution and higher CO2 emissions than driving at 30mph.
Richard Tracey, London Assembly Conservative Transport spokesman”
Richard Tracey might have a point that speed cameras are not popular, but he does seem to be exaggerating just how many would be necessary to ensure that 20 mph zones are effectively enforced.
Alex Hosking TBF, I don't think either side is great on free speech these days, so many people don't get it and just resort to ad hominem. It would be good if we as a part b...
graham Thanks Mark. I too enjoyed the film Conclave which is based on Robert Harris`s novel of the same name which is a page turner. Like the previous film "Two Popes"...
Daniel Stylianou Morgan - looking to the Australian model doesn’t really help because members of their Senate are directly elected, just as in the US system. It goes back to t...
Craig Levene Sarah Campion, Dan Carden , Andy Burnham. Have all called for a further enquiry, & rightly so. Reading Dan's statement, it certainly resonates. These horrif...
Paul Barker Just on the point of comparison, I know from experience that German Trains are much worse than those around London & The South-East. Again, they seem to ha...
Paul Walter reports …
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