tomsutton529
Member
- Messages
- 837
- Location
- North West
We have no fixed cameras in Pembrokeshire so only encounter them when traveling.
Average speed cameras are great fun as so few people are numerate:
Simplified scenario (not dissimilar to actual situation on A40 elevated section at Port Talbot, except 50mph not 60mph):
Most people seem to think the answer is 90mph on the basis that 30 + 90 divided by 2 is 60.
- 2 miles of average speed limit of 60 mph
- Due to traffic cover first mile at 30 mph.
- How fast can I drive over the second mile and not get flagged?
Actually you can travel at the speed of light if you could:
2 miles at 60 mph takes 2 minutes (60mph is one mile per minute after all)
1 mile at 30mph takes 2 minutes, so all your 'allowed' time has already passed.
Even if you traveled the second mile at 180mph - one mile every 1/3 of a minute - you have taken 2 1/3 minutes to cover 2 miles which is
51.4 mph
So I'm that bloke in the big old black Jaguar thundering past you, supercharger whining, 'slightly outside ACPO guideleines' once the last camera gantry is in view on those stretches I know well. When the road ahead is clear and it is safe to do so - as I was taught back when that sign meant 'end of restriction' not 'National Speed Limit'.
(and who gets ticked by the regulars who know where they are on their local roads and I don't. Any A14 regulars? )
I have often tried to work that out, cheers for that.