Is the noose tightening, or is my satnav dodge?
Discussion
I do 700 miles a week on the m1. The cameras are definitely set to 77mph or above.
My sat nav doesn’t show my speed but car speedo at 80 doesn’t cause a flash. What I would say is are you sure it was you that caused the flash?
I’ve been through them when other cars are flashed and they are very bright and disorientating. It’s often difficult to tell what’s causing them. I was once convinced I had been flashed but could t have been as I was doing 74. Any way nothing arrived so it can’t have been me, but it’s very hard to tell is my point.
My sat nav doesn’t show my speed but car speedo at 80 doesn’t cause a flash. What I would say is are you sure it was you that caused the flash?
I’ve been through them when other cars are flashed and they are very bright and disorientating. It’s often difficult to tell what’s causing them. I was once convinced I had been flashed but could t have been as I was doing 74. Any way nothing arrived so it can’t have been me, but it’s very hard to tell is my point.
Edited by Flumpo on Monday 2nd December 05:05
BertBert said:
Got a double flash this evening northbound on the M1 with the cruise on and set to 77 on the satnav. I guess we'll see if my sat nav is wrong when the nip arrives!
I think we have seen people done at 78, so we'll see.
Bert
A colleague got flashed going northbound around Luton a good 4 weeks ago and has heard nothing, he travels that route regularly and mentioned that he always sets his cruise at 79 and this time got the double flash, its his own car so NIP would have gone to him, this was circa 5am and no one was anywhere near him so it him for sure.I think we have seen people done at 78, so we'll see.
Bert
Perhaps they set it to flash / record at lower speeds, but actually only prosecute those doing above the accepted margin.
That's a double win for them, as being flashed encourages you to dial your speed down a couple of notches while you worry for a few weeks.
They end up just doing the people they wanted anyway. 10% + 3mph wallers or whatever it is.
That's a double win for them, as being flashed encourages you to dial your speed down a couple of notches while you worry for a few weeks.
They end up just doing the people they wanted anyway. 10% + 3mph wallers or whatever it is.
My car (VAG) can show a digital speed of 1-2 mph different either way to the set cruise speed. That doesn't allow for speedo error itself.
It is quite possible that you were at 78 and in NIP territory.
I tend to run mine at 3-4 mph less than the guideline (e.g. 64 in a 60) and have not had a nip, my commute covers 15 miles of managed motorway so lots of cameras.
It is quite possible that you were at 78 and in NIP territory.
I tend to run mine at 3-4 mph less than the guideline (e.g. 64 in a 60) and have not had a nip, my commute covers 15 miles of managed motorway so lots of cameras.
Pegscratch said:
Setting your cruise control to a number with near zero margin for error based on the display of a non-calibrated device which bases it's display on a very infrequently updated GPS signal compared to what is required for accurate speed information is very likely to end in tears.
GPS signals are constant with very precise timing synchronisation, speed is calculated based on the doppler shift of the received signal and is typically accurate to +or-0.5%. It is NOT done using a speed/distance calculation which many believe. Pica-Pica said:
For what it’s worth, I set my speed limiter at
33
45
55
65
78
Using gear and final drive ratios and rolling circumferences, to keep within NPCC guidelines.
Which begs the question, does anyone know which counties do NOT abide by the NPcC guidelines?
https://www.autoexpress.co.uk/car-news/106674/uk-speed-camera-tolerances-revealed-is-your-cars-speedo-accurate33
45
55
65
78
Using gear and final drive ratios and rolling circumferences, to keep within NPCC guidelines.
Which begs the question, does anyone know which counties do NOT abide by the NPcC guidelines?
speedyguy said:
75 would have been prudent, 77 taking a chance.
Is it really worth the mither for 2mph ?
I was thinking that 77 wasn't taking too much of a chance with enforcement starting at 10%+2, ie 79. However if it now starts at 78 or lower then it's a slam dunk to get a ticket doing 30k motorway miles a year.Is it really worth the mither for 2mph ?
And then as the earlier poster points out, I don't know how accurate my sat nav is anyway. Although if GPS is used to log lap times with only about 0.01 seconds difference to transponder based timing, it #should# be accurate enough on the motorway at 77mph - as answered above.
Pica-Pica said:
For what it’s worth, I set my speed limiter at
33
45
55
65
78
Using gear and final drive ratios and rolling circumferences, to keep within NPCC guidelines.
Which begs the question, does anyone know which counties do NOT abide by the NPcC guidelines?
Are there actually any NPcC guidelines? I thought the old ACPO guidlelines had stayed just that, old ACPO guidelines. I presume I'm about to tell you that the 4 lane section of the M1 past East Midlands airport does not use those guidelines when my NIP for 77 or 78 comes through!33
45
55
65
78
Using gear and final drive ratios and rolling circumferences, to keep within NPCC guidelines.
Which begs the question, does anyone know which counties do NOT abide by the NPcC guidelines?
Anyway, all told, not worth the mither, more prudence required. Perhaps for a novelty as noone has had a go yet (for which my thread is grateful), maybe keeping to the limit is actually a thing! And I certainly ca't be bothered with all that slowing for a camera nonsense.
Bert
Graveworm said:
Hmm, Nottinghamshire refused to confirm whether a threshold exists. I wonder if I was in Nottinghamshire, Derbyshire or Leicestershire at the time?TuonoPants said:
Pegscratch said:
Setting your cruise control to a number with near zero margin for error based on the display of a non-calibrated device which bases it's display on a very infrequently updated GPS signal compared to what is required for accurate speed information is very likely to end in tears.
GPS signals are constant with very precise timing synchronisation, speed is calculated based on the doppler shift of the received signal and is typically accurate to +or-0.5%. It is NOT done using a speed/distance calculation which many believe. - how often are you polling the GPS status or receiving notifications from the GPS hardware of a location change?
- what is the accuracy of the GPS update you're currently processing? (eg. typically the updated includes a positional "circle of uncertainty" which can be for example 10m or more in size depending on how many satellites you can see and trust in that particular update)
- how often are you updating your presentation layer (screen) with the latest speed value that you've calculated?
- how are you rounding the speed value you've calculated? is 77.56748646 mph showing as 77 or 78?
etc. etc.
Even if a system exists which uses doppler shift you are still relying on something to process a signal of varying quality/accuracy depending how well the device can "see" the GPS satellite through the windscreen or whatever, to perform calculations, rounding etc and to update a screen in a timely manner but not so timely that the screen display is constantly flickering or hunting between different speeds.
Pegscratch is right, to leave no margin for error against a calibrated piece of equipment fixed to the roadside is a dangerous game.
48k said:
Pegscratch is right, to leave no margin for error against a calibrated piece of equipment fixed to the roadside is a dangerous game.
He actually said "near no margin of error". So that's the exact point. How near is near? It appears that 77 is too near (to what we may find out).Bert
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