As readers of this blog will know I regard the introduction of 20mph speed limits as a good thing, and as I have said elsewhere, it has been known for well over 20 years that, as traffic speed increases, so does the risk to pedestrians:

  • Hit by a car at 20 mph, 3% of pedestrians will be killed – 97% will survive
  • Hit by a car at 30 mph, 20% of pedestrians will be killed – 80% will survive
  • Hit by a car at 35 mph, 50% of pedestrians will be killed – 50% will survive
  • Hit by a car at 40 mph, 90% of pedestrians will be killed – 10% will survive
  • Hit by a car at 50 mph, >99% of pedestrians will be killed – < 1% will survive

Many drivers don’t think about the fact that at 30 mph, a vehicle travels 44ft (roughly three car lengths) every second and at 20mph a vehicle travels 29.3ft (roughly two car lengths). The average reaction time of drivers is between 1 and 1.5 seconds, it takes time to stop, drivers have to think ahead rather than just trying to react to the situation. Lowering the speed limit allows driver more time to think and therefore reduces the frequency of accidents collisions.

However, if a 20mph speed limit is to be effective it has to be enforced, so I was very disappointed be the following twitter correspondence:

which leads to the question what are 20mph speed limit for? Or for that matter what are the police for, if they lack any real interest in community safety? Clearly the police aren’t interested in saving lives by enforcing speed limits, which may go some way to explain why the rate of pedestrians being killed or serious injury on our roads is currently increasing. This will continue to increase until driver change their behaviour and realise that they have a responsibility to drive below the speed limits and stop killing people.

Addendum: The above data on death rates includes children, in resent years groups such as RoSPA have taken to excluding children from their data, in order to play down the risk from motor vehicles. I find this practice utterly disgusting.