Doug's Darkworld

War, Science, and Philosophy in a Fractured World.

Posts Tagged ‘risk assessment

No brainer, it’s just common sense that making people wear bicycle helmets is a good idea and will reduce injuries and death, right?

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“It’s just common sense” is probably one of the most seductive and deadly false arguments out there. When someone says “it’s just common sense” what they are really saying is “reality conforms to my idea of what makes sense.” Yes, often times reality does indeed operate in a perfectly “sensible” matter. However, it is under no obligation to do so, reality operates under its own rules. And I’m pretty sure that a lot of people really don’t quite grasp this. And a good example of this is bicycle helmets. I mean, it just makes sense that if everyone wore bicycle helmets, there would be fewer  bicyclist deaths and injuries? And if absolutely nothing else changed if one forced people to wear helmets, yes, that would be the case. Unfortunately, reality has other ideas. Many or most states and countries that passed mandatory bicycle helmet laws saw their bicycle deaths and injuries rise as a result. How the hell is this possible?

It’s possible because when it comes to bicycle safety, there’s whole host of other factors besides just what the person on the bicycle is wearing. For example, and I bet no one predicted this, studies have now shown that you’re more likely to be hit by a car if you’re wearing a helmet! Yes, car drivers on average cut more than three inches closer to a person on a  bicycle wearing a helmet! And that three inches is going to turn a certain number of near misses into hits, and the bicyclist always loses when hit by a car. Why do drivers cut closer to bicyclists wearing helmets? Who knows, it’s almost certainly an unconscious action.

And there, in nutshell, is the crux of this issue. Human behaviour. When a change is made in some behaviour, the humans engaged in the behaviour will act differently. So any activity where human behaviour has a lot to do with how safe it is, any sort of mandatory safety law might have the opposite effect of intended. Australia was a great example of this, bicycling was becoming popular in the 90s, and even though the bicycle accident and death rate had been dropping steadily, they passed a mandatory helmet law to make it even safer! And bicycle deaths and injuries, including head injuries, went way up!

What the hell happened? Well, turns out, bicycling had been getting safer because with more and more bicyclists on the road, motorists got used to watching out for them. When the helmet law was passed, women in particular stopped riding because it messed up their hair. Fewer women riding meant that fewer men rode (the reason for this is hanging between men’s legs,) and the number of people riding bicycles dropped dramatically. So car drivers getting more careless about bicycles combined with the aforementioned tendency to cut closer to bicyclists wearing helmets, and boom. (Well, boom splat I guess.) And there’s other factors too, people wearing safety gear will almost always engage in riskier behaviour than those who don’t.

That’s called the Peltzman effect, the tendency of people to increase their risk taking as a response to safety regulations. Well, hypothesized and well studied apparent tendency. The whole field of risk assessment and accident prevention when it comes to humans is fraught with counter-intuitive facts that that defy common sense. At least when examined individually. I mean, yeah, if a head hits the pavement, it’s better off wearing a helmet. But when all of the heads hitting (or not hitting) the pavement are counted and analyzed, that’s where problems and counter-intuitive results can transpire when “common sense” safety regulations are passed.

One can factor in things like risk distribution too. For example, if one makes cars safer, car drivers engage in riskier driving. And this increases the risk to … pedestrians and bicyclists! So by making the car drivers and passengers safer, some of the risk has been passed onto bystanders basically. Great, so when an SUV is hurtling through the air toward me on the sidewalk, I can be gratified to know that the driver is probably pretty safe. This is why I stand well back from the curb on sidewalks and keep my eyes peeled. I’m probably more likely to be struck by pots falling off windowsills this way, but that’s a risk I’m willing to take.

Another example of this is intersections. If there is a bad intersection with a terrible accident rate, fixing it  (increasing visibility, etc.) will drop the accident rate at that intersection. (Yes, in this case commons sense applies.) However, the accident rate at nearby intersections will go up! Generally the benefit exceeds the loss in this case, but the point is that reducing risk when we are talking about mass human behaviours is complicated and the common sense approach may very well yield mixed or even negative results.

And that’s my only point here, common sense is a fiction, there really is no such thing. Reality and society is what it is, not what makes sense. Now, observation and logic, that’s not a fiction. It’s just hard. Especially when faced with counter-intuitive results. That’s why I’m here though, trying to make sense of it all. In any event much of the info for this post came from this article. Other tidbits came from a documentary TV show on risk assessment and safety I saw some years ago. And some came from Wikipedia. When I find a corporate sponsor (hint hint) I’ll be able to spend eight hours on posts instead of one or two, and will have time to track down and link to all my sources. Until, then, well, hopefully some peeps enjoy reading Doug’s Darkworld, because I enjoy writing it.

Ride and drive safely everyone!

(The above image is being used legally as far as I can tell under a Creative Commons license. It’s not being used for profit and the copyright holder does not endorse Doug’s Darkworld. Credit and Copyright: Peacay. It’s a nineteenth century illustration of bicycle gymnasts. Apparently bicycle helmets hadn’t been invented yet if the illustration is any indication. I just thought it was interesting, these were the skateboarders of their time.)




Written by unitedcats

October 7, 2010 at 7:23 am