Mark Foster
Do they?
Can you think in graphs and curves? Use a bell curve for simplicity.
Imagine the distribution of actual 'safe speeds' for a narrow road between houses with a lot of kids about during the day. I would think it would peak at about 30mph with about +-- 20mph variance. Obviously there would be long tails on the curve stretching down to 0mph (street party going on) and up to 100mph (4am, residents all warned, doors all barricaded etc). But the peak is at 30mph+--20mph.
The limit on this road is likely to be 20 or 30mph.
Imagine the distribution on a straight stretch of Motorway. Actual safe speeds peak at maybe 90-100 with a variance of +--50mph. The limit is set at 70mph.
The fact that the curve in the first case is down near the 20-30mph limit and in the second is up at 70mph shows that there *is* a correlation.
The first 'actual safe speeds' curve (30mph+--20) would not be the case in a 70mph limit. Not ever.
In a stupidly low limit area where actual safe speeds are 50mph+--20 but the limit is 30mph, the correlation between safe speeds and the limit is much lower. Which is *exactly* why it is a stupidly low limit.
