Comment Re:How are the photos even considered evidence? (Score 1) 566
Well just for fun, let's crunch some numbers.
Ref: The Highway Code, HMSO. Sections 117 to 126, "Control of the Vehicle", subsection 126 "Stopping Distances".
Disclaimer: some calculations done with WolframAlpha.
Let's assume the posted limit is 40MPH. That means that in each second, the vehicle will travel 17.88 metres, or 58.67 feet.
Now let's assume the vehicle is travelling at 60MPH. 26.82 metres per second, or 88ft/sec.
In order to fool the GATSO, we have to be travelling at or below 40. That means we need to lose 20MPH.
Thinking time at 60MPH is 18 metres, plus 55 metres for the vehicle to come to a complete stop.
This means the assumed reaction time is about 0.67 seconds.
The camera is 50ft down the road from the RADAR speed sensor (the GATSO itself).
This means that in 50 feet (15.24 metres), we have to:
* Realise the camera is there
* Pull off what amounts to an all-out emergency stop (brakes hard down and fight against the Anti-Lock Braking system)
* Lose 20MPH of speed
* Release the brake before the camera goes off
Let's say it actually takes 60 metres to stop the car. That means we lose 1MPH for every metre travelled. Thus, 20 metres travelled. 0.75 seconds.
So if it takes a human 0.67 seconds to realise "Aargh, that's a GATSO" and slam the anchors on, plus a further 0.75 seconds to slow down sufficiently, the vehicle needs to be at least (0.67 + 0.75) = 1.42 seconds away. Working backwards, we get 124.96 feet, or 38.08 metres. Add a bit for the guy to release the brake before the camera flashes and this just doesn't hold water... we're talking about 45 or 50 metres total.
So based on our previous assumptions:
* The vehicle is travelling at 60MPH
* The speed limit is 40MPH
* The driver has an average reaction time per the Highway Code baseline standard
There is no way an average person, in an average car, could slow down sufficiently in 50 feet to get a positive hit on the RADAR, but get a negative on the photo. An F1 or WRC rally driver with a full Advanced Driving license, experience and lightning-fast reactions, driving a shiny new sports car *might* be able to pull it off, but not your average Joe Q. Public in his clapped-out Vauxhall Astra or Ford Focus. Give the guy a Citroen 2CV and it's an even more absurd proposition!
QED, folks. Can someone prove me wrong, or improve the proof? *GRIN*
Ob disclaimer: this, of course, does not take into account the deceleration of the vehicle. Not that it's likely to make a big difference to the end result.