What to do when you've got better data?
Discussion
I've just had a letter through from the local police informing me that one of our cars has been recorded by a civilian volunteer speed awareness group exceeding the posted speed limit, specifically 39mph in a 30mph zone. No action to be taken but it will be recorded potentialy for future use.
The car is a development vehicle and as such has a pretty extensive telemetry and data suite onboard, the bits which are important with regards the above being:
- Twin redundant 20hz GPS recievers
- None contacting optical speed over ground sensor
- Redundant wheel speed sensors, diff speed sensor and gearbox input shaft speed sensor
- TPMS which is accurate enough to account for the differences in rolling radius of the tyre due to thermal changes.
And it logs all that in a time stamped form with position data. From that I can see that car in question was on that road on that day and the maximum speed it achieved was 28.7mph as an average from all four wheel speed sensors, this figure is backed up by the ratio calculation based on diff speed and again by the calculation based on gearbox input shaft speed. The GPS agree with it to +/- 0.05mph.
I really want to write back, present our data and request that the do gooders involved are trained properly and evidence of this is provided to avoid future incorrect recordings. Or shall I just screw their letter up and chuck it in the bin?
The car is a development vehicle and as such has a pretty extensive telemetry and data suite onboard, the bits which are important with regards the above being:
- Twin redundant 20hz GPS recievers
- None contacting optical speed over ground sensor
- Redundant wheel speed sensors, diff speed sensor and gearbox input shaft speed sensor
- TPMS which is accurate enough to account for the differences in rolling radius of the tyre due to thermal changes.
And it logs all that in a time stamped form with position data. From that I can see that car in question was on that road on that day and the maximum speed it achieved was 28.7mph as an average from all four wheel speed sensors, this figure is backed up by the ratio calculation based on diff speed and again by the calculation based on gearbox input shaft speed. The GPS agree with it to +/- 0.05mph.
I really want to write back, present our data and request that the do gooders involved are trained properly and evidence of this is provided to avoid future incorrect recordings. Or shall I just screw their letter up and chuck it in the bin?
poppopbangbang said:
- TPMS which is accurate enough to account for the differences in rolling radius of the tyre due to thermal changes.
balls-out said:
WOW - I would have guessed these are TINY. So what sort of difference do thermal changes make - sounds like something I HAVE to know - Surely such knowledge will impressed my friends.... (err not that I have many of course - I wonder why).
Depends mainly on the tyres construction but what you see from the increase in pressure as the tyre heats is an increase in rolling radius. On a run flat (low profile, mega stiff sidewall) its almost none existent, on an F1 tyre its massive. With accurate enough wheel speed information and gearbox input shaft speed information you can plot what difference is present across a tyre pressure/temperature range. For super accurate tyre temp we'll use three IR pyros in the arch and an ambient air temperature sensor inside the wheel. poppopbangbang said:
No action to be taken but it will be recorded potentialy for future use.
Can any of the resident BIB explain what this might mean?In the case of being caught speeding again would they bring this up again to show a history of excessive speed?
I'd definitely take the time to write back as their measurement was approximately 35% out. That's a pretty sizeable error. At 70 they'd have you doing 95!
I assume they've actually wrote someone else's speed beside your reg number.
I use a speed gun from time to time, they are pretty idiot proof. They need calibrating from occasionally but we check ours with a tuning fork every time so we know it’s accurate. Chances are they with miss read / transposed numbers or were picking up a different vehicle. Either way it’s a bit of a cock up!
Doubt you’ll get anywhere, I doubt the person who “caught” you will remember but will be interesting to see the police response.
Doubt you’ll get anywhere, I doubt the person who “caught” you will remember but will be interesting to see the police response.
Sounds like it's not a BiB failing, but those f
king Community Speedwatch fking geriatric fking s who are waiting for death and trying to ps off as many people as possible before they cark it. "Ooh he's going too fast Mavis, we can't have that, cars in my day were slower, dribble fart stroke"
Yes I got a knock on the door from Plod after giving the aforementioned geriatric mofos a piece of my mind one day, after I found them parked on DYLs about 5m from a junction, using the gun while sitting in the car. Lazy fking geriatric old s.
king Community Speedwatch fking geriatric fking s who are waiting for death and trying to ps off as many people as possible before they cark it. "Ooh he's going too fast Mavis, we can't have that, cars in my day were slower, dribble fart stroke"Yes I got a knock on the door from Plod after giving the aforementioned geriatric mofos a piece of my mind one day, after I found them parked on DYLs about 5m from a junction, using the gun while sitting in the car. Lazy f
king geriatric old s. DuraAce said:
Jayyylo said:
Can any of the resident BIB explain what this might mean?
In the case of being caught speeding again would they bring this up again to show a history of excessive speed?
Section 59 ASBO? They don't need any real evidence In the case of being caught speeding again would they bring this up again to show a history of excessive speed?
I have had this explained when I've made reports of careless / dangerous driving - knowing full well that a single anecdotal report from someone whop is not a sworn officer is unlikely to result in a prosecution ... but when/ if they are caught / seen by police if the intelligence is there there will be a stronger case to procede vs giving 'words of advice' or offering a caution / course etc ...
Gassing Station | Speed, Plod & the Law | Top of Page | What's New | My Stuff