Safety Theatre

What do the following things have in common:

  • Bike Helmets
  • Sharrows
  • Marked Crosswalks
  • Fining Pedestrians

They are designed to make people feel safer than they are. The natural reaction is a misjudgment of actual risk due to risk compensation. The result is that people don’t behave safely enough, which makes it more dangerous.

In contrast, when people feel less safe, they behave in a safer way, which improves safety compared to normal behaviour in the same circumstances.

For instance in the controversial case of bike helmets, I am not saying if you are dropped on your head, wearing a helmet doesn’t reduce the chance of your head splitting open. I am saying it increases the likelihood of being dropped on your head. The total risk of your head being split open is the product of these two factors:

P(HeadSplitOpen)=P(DroppedOnHead)*P(HeadSplitOpen|DroppedOnHead).

Helmets are associated both with P(HeadSplitOpen|DroppedOnHead) decreasing and P(DroppedOnHead) increasing. How this nets out is an empirical question, whose answer varies depending on context.

There are many countries without bike helmet laws that have a higher rate of bicycling and fewer injuries, indicating that the main safety feature is not helmets, but the general culture around cycling. There is evidence, for instance, that cars drive nearer bikes when the bicyclist is wearing a helmet. The safety-in-numbers effect is more important.

Sharrows are painted arrows on the road saying bikes can share the road. In fact, bikes can share almost every road, and the arrows do almost nothing (perhaps increasing the likelihood bikes are riding over the painted part of the road) for ridership, and are at best a poor substitute, and probably an increase in relative hazard compared with no change or installation of bike lanes..

To the credit of RMS, marked crosswalks are used more consistently in New South Wales than in the United States, where it is totally random, but what do the zebra crossings really mean? That a car is supposed to stop for you if you step into the street. But if you step into the street and there is no marked crosswalk, a car is still supposed to stop for you, not run you over. At a zebra crossing the car is also supposed to stop if you are at the side of the road waiting to cross, compared with an unmarked crossing. The behaviour once you have stepped into the road is supposed to be unchanged (i.e. the car is supposed to avoid hitting you). It may be argued that the paint will cause a driver to be more alert for the pedestrian at that location, i.e. to expect a pedestrian, and therefore slow down in anticipation. But it also causes the pedestrian to be less alert for the driver, and drivers to be less alert in unmarked locations. The paint doesn’t actually increase your safety. In fact a large study in the US found that at uncontrolled locations, after controlling for other factors, the presence of a marked crosswalk was more dangerous than an unmarked crosswalk.

Rather than focus on these theatrics (and others such as fining distracted pedestrians – a misguided initiative of a local so-called pedestrian safety group), we should work toward making the world actually safer for pedestrians and bicyclists. This requires, among other things, reducing the speed of vehicles anywhere that pedestrians might appear (so both drivers and walkers have more reaction time and do less damage in the event of a crash), increasing the reaction time of vehicles when drivers or the sensors in a car detect a pedestrian, separating pedestrians and bicyclists where they cannot be safely mixed, and increasing the likelihood of detecting a pedestrian or bicyclist by reducing driver distraction (and motivating drivers appropriately with more severe penalties for crashes they are responsible for).  It’s a shame we don’t do this.

Security Theater operates the same way, producing many visible signs of the security apparatus at work, but taking resources from more effective but less intrusive strategies.

One comment

Comments are closed.