In a spin: Speed cameras and the fallacy of road safety.

Recently, with the cut in funding and subsequent turning off of speed cameras in Oxfordshire there has been a great deal of chatter about how this will increase the numbers of deaths on the roads. Today had the local speed camera organisation, “Thames Valley’s Safer Road Partnership”, spouting statistically unsustainable statistics about how many people were now breaking the speed limit as opposed to when the cameras were operational. (Notably, they didn’t say by how much the speed limit was being broken by. Also, one location is notorious for chavish lads driving recklessly, which wouldn’t be halted by the camera.) www.bbc.co.uk/news/uk-england-oxfordshire-10929488

Two days ago we had another pressure group and a number of police chief constables put their oar in: www.bbc.co.uk/news/uk-10911436. One basically saying that there would be carmogedden and the other blaming the middle classes for speeding “until one of their family got killed.” That second one is laughable if you’ve ever lived anywhere close to a “working class” neighbourhood.

The trouble with all this spin and hoo-hah is that the evidence for speed being the main killer on the roads is just not there. In 2008 only 14% of road accidents had speed as a contributory factor. www.dft.gov.uk/pgr/statistics/datatablespublications/accidents/casualtiesgbar/rrcgb2008 Note that this is ALL accidents reported to the police and not just lethal ones. So, speed cameras, even if they were 100% effective, would not help in 86% of accidents.

So, now we know that speed is not as high a risk as the quangos who run the cameras and the police forces (who don’t want to spend money on traffic enforcement officers) would make out, do cameras actually help at all?

Well, in some locations I’m sure that they do. In most locations, however, they’re more of a hazard than a help. How many times have you seen a car brake heavily (usually from a speed under the speed limit already) to pass a speed camera? I’ve seen it quite a number of times, causing the cars behind to have to make sudden braking maneuvers themselves. i.e. increasing the risk of an accident. Also, forcing drivers to be more concerned about the absolute speed of their vehicle and watching the speedo more and more decreases the time they have to concentrate on other road hazards or taking note of what an appropriate speed for the situation might be, again increasing the risk of an accident.

If you add to this the congestive effect of cars slowing to well below the speed limit to pass the cameras and, on a road close to capacity, causing the generation of a solitary wave of congestion to pass back along the queue causing a complete jam.

What about the other “safety” features imposed by local authorities on the roads in the name of safety?

Well, there are the extensive 50 mph speed limits which seem to encompass huge swathes of the A road network. It seems that the default reaction when there are an above average number of accidents on a road is to restrict the speed limit by a mere 10 mph. The fallacy here is that doing so will automatically cut incidents.

Let’s break down the logic using a specific example, the A420 between Oxford and Swindon. There are a few places where the junctions are relatively blind and would benefit from the traffic being slowed. It could be said that in these areas 50 mph is still way too high and a 40 mph limit would be more appropriate in the close vicinity of the junction. However, for most of the road the national speed limit of 60 mph is not a dangerous speed (under good road conditions). The majority of fatal accidents on the road, however, are from drivers who have been reckless and have been speeding, losing control of their vehicle on bends. Note: these people are already breaking the speed limit.

So, the knee-jerk reaction has been to decrease the speed limit on about two-thirds of the whole length of road to 50 mph. Firstly, his will not help to greatly reduce the danger on the risky junctions as the time to see a vehicle from the junction before turning out onto the road has not decreased by much. Secondly, those who caused accidents by speeding recklessly will still ignore the speed limit. (And no, more speed cameras wouldn’t help.)

In other words, the responsible majority have been hugely inconvenienced and no real good has come from it other than to allow the councils to say that they’re doing something.

Of course, I am talking heresy. Tut-tut. The slogan says, “Speed kills!” but actually it doesn’t. Changing the slogan to “Inappropriate speed is highly risky” wouldn’t go down well as it’s not punchy enough. Of course, it’s not the speed which kills ultimately, it’s the rapid deceleration.

Just my two-penny’s worth…

7 thoughts on “In a spin: Speed cameras and the fallacy of road safety.

  1. On the A41 road I take often to my parents’ place, there is a village called Kingswood, which has a speed camera. Drivers see the camera only from a fairly short distance, and tend to slam the brakes on to reduce to 30mph – I have got used to this being a tremendously dangerous place, and always stay well back from other cars.
    Thing is though, the limit on that bit of road is 60mph, and the camera is simply intended to stop people exceeding that.
    What it illustrates rather well, I think, is that many drivers simply don’t know the rules on the bit of road that they inhabit because they don’t notice road signs, and they have no feel for what might be an appropriate speed – that is what can make speed cameras dangerous.

  2. Whether or not they have a +ve/-ve effect on safety, one aspect still remains: if you’re speeding, you’re breaking the law. Stay within the limit and there are no issues. Why is that such a problem for people?

  3. “How many times have you seen a car brake heavily (usually from a speed under the speed limit already) to pass a speed camera?”

    Once. I’m not usually that close.

    ” Also, forcing drivers to be more concerned about the absolute speed of their vehicle and watching the speedo more and more decreases the time they have to concentrate on other road hazards or taking note of what an appropriate speed for the situation might be, again increasing the risk of an accident”

    That’s poor driving. If one is unable to accurately judge speed without frequent recourse to the speedometer, hie thee to refresher training and practice.

    “In other words, the responsible majority have been hugely inconvenienced and no real good has come from it other than to allow the councils to say that they’re doing something.”

    Completely disagree. Dropping your speed by ten mph adds a marginal amount to your journey time, and will increase fuel economy. Given the cost of fuel, this is most convenient (“Pay less tax! Drive slower!”).

    Nick Daisley: “What it illustrates rather well, I think, is that many drivers simply don’t know the rules on the bit of road that they inhabit because they don’t notice road signs, and they have no feel for what might be an appropriate speed – that is what can make speed cameras dangerous.”

    Yes, but: the camera itself is inanimate. It does nothing, it is the poor drivers’ response that is dangerous. Blaming speed cameras is a rather lame attempt to shift responsibility for bad behaviour. They are one piece of the environment, which must be accounted for like any other; failure to do so is the fault of the person, not the camera. One can argue about their efficacy, siting, purpose and aesthetics till the crack of doom, but failure to account for them is the individual’s problem, no-one elses.

  4. @James – yes, I expressed that badly. It is the reaction of drivers to the cameras that is dangerous, not the things themselves.
    Incidentally, have been checking figures – apparently with most (reasonably) modern cars, every 5mph above 50mph uses around 10% more fuel: another fine reason for not driving like a loon, methinks!

  5. James: “How many times have you seen a car brake heavily (usually from a speed under the speed limit already) to pass a speed camera?”

    Once. I’m not usually that close.

    That’s a sweeping comment, James.

    I regularly drive from Oxford to Reading over the Chilterns (A4074). Much of the road is a comfortable 50mph limit, some 60.

    When one enters Chazey Heath just before Caversham there is a speed camera. This camera is set at 50. The limit in CH is 50.

    Most cars are already driving at 50 before the village.

    This is (at certain times of the day) quite a busy route and there is frequently a traffic queue moving at this speed.

    To have one idiot slam on the brakes because they’ve seen a camera (despite already being at the limit) and frantically drop there speed to UNDER 30 is crass ignorance of other road users at best and entirely dangerous at worst.

    I see this many days.

    despite whatever distance I may leave between me and the car in front, when a pillock does this I’ll still get a pretty good view of the number plate in front…

  6. James:

    “That’s poor driving. If one is unable to accurately judge speed without frequent recourse to the speedometer, hie thee to refresher training and practice.”

    The problem here is paranoia rather than being able to judge speed. The drivers are far more likely to worry that they are speeding and over-compensate.

    Also, if you are driving an unfamiliar vehicle it is *FAR* more difficult to judge your speed as all of the hints you subconsciously use, such as engine noise, transmission noise, throttle position etc. are different. This makes hire-car drivers even less attentive in this situation.

    “Completely disagree. Dropping your speed by ten mph adds a marginal amount to your journey time, and will increase fuel economy. Given the cost of fuel, this is most convenient (“Pay less tax! Drive slower!”).”

    The speed between 50mph and 60mph is the cross-over point between friction effects being dominant and aerodynamics being dominant in terms of resistance to forward motion. This is very much dependent upon the specific vehicle.

    Nick, the research saying that 50mph is the optimum speed for fuel efficiency is actually pretty old and was used as the basis for the 50mph speed limit in 1973 during the fuel crisis. I’m not sure if the research has been done on the current level of aerodynamics on modern cars. The aerodynamic retardation effect is non-linear and does increase quickly over about 60mph.

    Doing a back of the envelope calculation, dropping your speed by 10mph on the A420 (relative to the original 60mph all the way) actually adds over 11% to the journey time.

    Now, as for the effect of speed cameras, let’s analyse the statistics given in that article.

    On the Watlington Road, Cowley, the percentage of speeding cars rose by 88% during a five day period. Scary, until you find out that the total was 62 cars. That’s one car speeding approximately two hours! This is as opposed to one every 3.6 hours previously. Remember that this *IS* a busy road next to a housing estate renown for its speeding drivers.

    So, with all the down sides to cameras and the huge cost of maintaining them, is it really worth it for a demonstrably small problem?

    By the way, I’m not at all saying that speeding is good. Anyone who knows how I drive will attest that I strictly abide by the speed limits, even where I disagree with them.

  7. A generic statement:

    I was once nearly involved in a pile up on the M4 due to a truck braking hard for a speed camera (there was a new speed sign followed immediately by a camera). The truck braked so hard that it’s trailer lost grip and went across three lanes.

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