lower urban speed limit will increase accidents

http://news.bbc.co.uk/1/hi/sci/tech/7358863.stm reports on new research that shows that our brains go into rest mode when we face an unchallenging task, such as a boring job.

In amusingly characteristic synchronicity, government has just announced that it will introduce a 20mph speed limit in towns to save lives.

I've argued before that lower speed limits cost lives based only on the increased proportion of lives spent in the car to get from A to B when you have to drive slower, and that they also increase accidents. See

http://www.btinternet.com/~ian.pearson/web/future/roaddeaths.htm and http://www.btinternet.com/~ian.pearson/web/future/driving.doc

This 'latest research' suggests that the effect will be even larger, with people's brains going into autopilot and reacting much slower to visual clues than normally, and consequently making far more mistakes. I for one almost fall asleep if I have to drive as slow as 30mph on an uncluttered road with few obstacles or dangers or pedestrians to track. Being forced by speed cameras to drive at only 20 will mean that my brain will almost switch off completely, or at least wander onto thinking about totally different things. Certainly, I will find it impossible to concentrate on driving at that speed unless the road is very challenging indeed, and very few urban roads are that difficult.

If people respond much more slowly to visual clues and make more mistakes, this will directly translate into more accidents. Although a smaller proportion of those accidents will result in deaths if they occur at slower speed, it is hard to see that implementing a policy that will increase the number of traffic accidents will be sensible. We will have more injuries, even if the number of deaths is lower.

As I said in my articles above, it would be far more sensible to concentrate efforts on reducing the far greater number of avoidable deaths in hospitals, because the benefit:cost ratio would be a great deal better.