SafeSpeedv2 wrote:
....An average of the 85th%ile
I know what you mean though !
Not the point - the point of course is that they take the 85th%ile when all conditions are good on an average section of the road so it is the
true unimpeded Free Traveling speed that the driver has chosen to be safe to proceed.
As opposed to the common sense approach you're suggesting ...
What's usually done, is one of those 'your speed is' devices is immediately preceded by a posted speed 'limit'.
People see the posted speed 'limit' first, weigh that against time of day, pedestrian traffic likelihood, the possibility that the area might be a speed trap, etc.
What tends to wind up happening, is that the speed distributions through the area will show people like me driving through the area at anywhere from 10 to 15 MpH over the posted 'limit', and the vast majority of people driving through the area at around 7 to 10 MpH over the posted 'limit'.
If enough people drive through the area at more than 10 MpH, and the 'your speed is' sign disappears, you can bet that area has become a speed trap. I know, I live within walking distance of one. It's precisely because pedestrian traffic in that area will never reach a frequency that would slow drivers down - among many other things of course - that make it such a good hunting ground.
Usually, the survey finds that most people are not driving through the area at speeds which cause concern.
Login
Register
FAQ
Search
Members
