SafeSpeed wrote:
15mph? Why?
If you only ask folk to provide 15mph's worth of attention you only get 15mph's worth of attention - and actually that isn't much. So suddenly almost all of the impacts (which always did result from attention failures) will be at around 15mph.
And even 15mph is a deadly speed
This really is one of the stupidest road safety ideas on the planet. We have an amazing road safety system based on the behaviour of human beings as skilled risk managers - and people like you wish to take their ability to manage risk away.
I thought there were no "wrong" or "right" ideas in the context of Brainstorming, or maybe you're just "inciting hatred" by rebuking my idea formally?
Anyway, the limit really was arbitrary. I was using the Joksch curve to generate a dV of 10mph as p(fatal)~0.1 at this dV, making the assumption that VRU's are 200% more likely to be killed than a car occupant in a crash.
It may well be worse, I don't know the exact figures for VRUs (I used DfT 20% die at 20 as a rule of thumb to generate my 0.1 figure which probably isn't linear.)
Anyway, in reality this would give:
1) A stopping distance which is virtually instantaneous for a good vehicle in good conditions.
2) Consistent and expected driving behaviour.
3) More time for COAST, as people would not need to worry about "limits". If the road ahead is clear, then maximum speed can be applied. If not, then slow down as normal.
The only places where this would be introduced would be highly urbanised environments or residential areas. High pedestrian and hazard density.
Why is that such a bad idea? How exactly would it remove concentration from the road? How exactly would it be any worse than allowing someone to travel at 30 or 40mph in the same are (which generates a p(fatal) of somewhere in the region of 0.3-0.6% allowing for braking effects) which is unacceptably high risk for an environment containing so many hazards.