Those "Average 50mph" speed zones are nasty

MarkDavis

MarkDavis

MarkDavis

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I've noticed that quite a few of them have sprung up on the M1 near London and also on the M4 heading towards Bristol.

Previously I thought they were just there to slow traffic due to roadworks but they've installed multiple yellow SPECS cameras hanging over the lanes to measure the speed you enter the zone, and the speed you exit the zone. No flash or radar appears being used, and it doesn't seem to show up on the TomTom POI camera database.

Over a 2 mile stretch of the M1 there must have been at least 4 entry/exit camera points and the M4 is even worse.

Anyone else notice these or been caught out by them? Presumably they don't work at night? Anyone know if there's a tolerance above 50mph that they allow?
 
Last edited:
PinkFloyd said:
AM I completely missing something here. :confused:
Your logic is baffling me.

The average of 40 + 60 is clearly 50.
40+60 = 100
100/2 = 50
Click to expand...

Don't forget that you're travelling at different rates.

For the 1st mile, you'd be travelling at 60mph. Therefore it takes you 1/60th of an hour to travel that distance ie 0.0166 (recurring) hours

The 2nd mile, you'd be travelling at 40mph, so it take you takes you longer - 1/40th of an hour to travel that distance ie 0.025 hours

Total distance is 2 miles which takes you 0.0416 (recurring) hours to travel that distance,

Therefore you're average speed over that distance is:-

2 miles / 0.0416 recurring = 48mph
 
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