Friday, July 23, 2010

Swindon - the Death of Speed Cameras?

Speed cameras - do they work?

To be honest, I've not made my mind up yet on all the issues. I rather agree with James May when he says: "Speed cameras are obviously for making money and not for saving lives, but that's only because the fines aren't high enough. Obviously they're not, because people are still speeding. That's why they're getting nabbed."

But the only thing I learned from the BBC's news items on the subject was that the BBC are not worth the license fee.
The 'Taxpayers Alliance' (Tory right-wing in disguise) featured large, as did Swindon Coucillors, with little balancing opinion - no road safety organizations, just a police officer and someone from the Safety Camera Partnership (who stood to lose her job and looked a little upset). The assertion that 'only 5% of accidents are caused by speeding' went unchallenged (I'll get to that later). The BBC need to realise that this subject is not celebrity gossip. People ultimately live or die based on the quality of this debate. The BBC coverage gave the distinct impression that the death of the speed camera was a good thing.
That's why you need to read this blog.

I am not a particular fan of speed cameras. Their very ubiquity in London must have a moderating effect on speeds, but the one near my house certainly has a very localised effect. But the people who oppose speed cameras don't have a great story on what they're going to do instead.

The Swindon 'trial' reports that accident rates have not increased since speed cameras were turned off. However, it is a little premature to draw the conclusion that speed cameras have no effect on accident rates.

  • Only 6 speed cameras in Swindon were turned off (source), and the tell-tale road 'ruler markings', signs  and the cameras themselves remained, albeit with a yellow hood: at a distance you a speeding motorist would have trouble telling the difference between the 'out-of-action' cameras and the real thing.
  • Swindon is not a large area and the trial lasted just a year.
  • There's a possibility of bias: the trial data has been produced by people with a vested interest in its success.
Two more points about the Swindon trial. 
  1. Swindon, instead of investing in speed cameras, instead invested in engineering measures, signs and education. So, if it's true that cameras have no effect, you would expect the accident rate to have gone down, not stayed the same (assuming the other measures were successful)
  2. Swindon's engineering, signs and education were paid for out of speed camera revenue. That means, if we got rid of all speed cameras, there would be rather less money for such measures. Because speed cameras are pretty much self-financing, you get a certain amount of 'free' road safety ( paid for by speeding motorists). So, if we follow Swindon's example, we'll have no speed cameras and less other safety measures (assuming the funding shortfall isn't made up by extra government grants - hardly likely in these austere times). You don't have to be Isaac Newton to figure out that's hardly a recipe for safer roads.
So let's take a very quick look at both some empirical evidence and some theory.
Theory first.

Speed both makes crashes more likely and more severe. The faster you drive, the less time you have to observe the road ahead and behind for hazards, and the less time you have to react to them. If you have less time to react and your initial speed is faster, your speed at impact will be faster. As any schoolchild knows, by Isaac Newton's laws, a faster impact involves more energy and hence a greater chance of death or serious injury.

What effect do speed cameras have? Firstly, you have to be either very unobservant, very distracted or driving fast to get caught, the cameras are so visible. So anyone who gets caught three times should, one could argue not be on the road - if three times you failed to see a 10-foot pole with a large yellow box on it, how many 5-foot children are you failing to see? The prospect of losing their license with another offence must focus the minds of those people.

Empirical evidence next.
According to Devon and Cornwall Safety Camera Partnership, "In the first two years of operation the number of injury collisions in this area has fallen by 27% and the number of people killed or seriously injured has reduced by 7%. However on those roads where cameras are used there has been a 44% reduction in crashes and a 17% reduction in casualties. Also the average speed of vehicles on the roads has reduced by 12% and the percentage of drivers exceeding the speed limit has been reduced from 64% to 33%."

1 comment:

  1. while cruising down the M4 in wiltshire last night, I could see that most cars going past had their satellite nav units up and running, even on the m-way. Given they give auto-warning of speed cameras, being caught by fixed-location speed cameras now has to be viewed as a competence tax.

    What wiltshire does have is ave speed cameras on the roadworks, and there is no way to avoid them. It's also hard to say "forces people to brake hard for a camera"; or "prevents overtaking", all it does is penalise people whose ave speed is too high.

    It'll be interesting to see whether the coalition supports/prevents rollout of these kinds of systems.