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Contesting speeding ticket with GPS data?
Nickp - 5/12/16 at 06:55 PM

Got an email today from our vehicle lease company saying I have a speeding ticket coming and they have passed my details to Notts Police. According to the BIB I was doing 37 in a 30 zone near Worksop.
Our company vehicles are fitted with a Tom Tom monitoring / tracking system so I asked my manager to check I was at the stated location at that time. Unfortunately I was, but on that stretch of road it recorded a top speed of 33mph and and average of 32mph through the entire 30 limit. I know I'm probably wasting my time but will contest it anyway.
Anyone had experience or heard of this sort of thing?


CosKev3 - 5/12/16 at 07:01 PM

I think I would do a test run somewhere to cross reference the speed on your data logging equipment against your speedo in car and perhaps a sat nav in the car too and see if the company logging is accurate?


bi22le - 5/12/16 at 07:18 PM

What frequency does the room ton record at. With a top of 33 and average of 33 it all may be possible to hit 37 with out it registering on a 5 second log frequency.


cliftyhanger - 5/12/16 at 07:20 PM

Hmm, so you will claim you were still speeding, but just not as badly?
Not sure that will go down well. Probably worth waiting to see what info they have. Just think carefully....


Nickp - 5/12/16 at 07:23 PM

quote:
Originally posted by cliftyhanger
Hmm, so you will claim you were still speeding, but just not as badly?
Not sure that will go down well. Probably worth waiting to see what info they have. Just think carefully....


So would they prosecute at a genuine 33mph?


Nickp - 5/12/16 at 07:25 PM

quote:
Originally posted by bi22le
What frequency does the room ton record at. With a top of 33 and average of 33 it all may be possible to hit 37 with out it registering on a 5 second log frequency.


Dunno yet, I'm going to enquire about the accuracy / technicalities of the system we use to help back me up if I do contest it.


craig1410 - 5/12/16 at 07:36 PM

I'd be surprised if any evidence you provide will affect the intended prosecution, especially when at best it confirms the offence.

I have a GPS dash cam and it tends to suggest my car speedo is almost 10% over-reading which from what I understand is pretty typical. Since car speedos must not under-read speed and may over-read by up to 10% then it's likely you were travelling at an indicated speed between 33 and 37.

Unless you have enough points already on your licence to make this offence cause you problems then maybe you should just take this as a slap on the wrist and leave it be. If you do decide to seriously contest the prosecution then perhaps you should seek professional advice or you might talk yourself into a court appearance instead of a fixed penalty and possibly an increased fine.


[Edited on 5/12/2016 by craig1410]


Nickp - 5/12/16 at 07:41 PM

quote:
Originally posted by craig1410
I'd be surprised if any evidence you provide will affect the intended prosecution, especially when at best it confirms the offence.

I have a GPS dash cam and it tends to suggest my car speedo is almost 10% over-reading which from what I understand is pretty typical. Since car speedos must not under-read speed and may over-read by up to 10% then it's likely you were travelling at an indicated speed between 33 and 37.

Unless you have enough points already on your licence to make this offence cause you problems then maybe you should just take this as a slap on the wrist and leave it be. If you do decide to seriously contest the prosecution then perhaps you should seek professional advice or you might talk yourself into a court appearance instead of a fixed penalty and possibly an increased fine.


[Edited on 5/12/2016 by craig1410]


I haven't got any points and been that way for years. Just frustrating tbh. If the GPS data matched their figures then I'd say 'fair cop'


SPYDER - 5/12/16 at 07:49 PM

Surely its a fair cop anyway. I can't see what can possibly be gained.
You'll be offered a Speed Awareness Course. Take it and keep your clean licence.


cliftyhanger - 5/12/16 at 07:54 PM

^^ Exactly.
If you start trying to challenge the case, it is quite possible they will not offer a speed awareness course. And as they are prosecuting anyway, they are unlikely to withdraw if you prove to them you were speeding.
Best to wait and see what course of action they will take. Different if you had evidence you were not speeding.


Nickp - 5/12/16 at 07:59 PM

quote:
Originally posted by cliftyhanger
Different if you had evidence you were not speeding.


That would be preferred


loggyboy - 5/12/16 at 08:13 PM

Wait to see what evidence they are relying on.
If they offer an awareness course they dont have to provide with much (or anything), id they offer a fixed penalty they may offer more but unless u choose court you wont get full disclosure.
I've challenged a gatso successfully when i measured the distances the photos showed and calculated it as 34 not the 37. This wasnt in court but can only assume they didnt have enough evidence the camera had been calibrated so could not prove it was correct so chose not to go to trial.


Nickp - 5/12/16 at 08:17 PM

quote:
Originally posted by loggyboy
Wait to see what evidence they are relying on.



Cheers, I will.


gremlin1234 - 5/12/16 at 08:20 PM

gps data will almost invariably under estimate the speed, due to it using straight line speed rather than following the road
for instance going round a hairpin corner, you may appear to have moved say 40metres, but easily done twice that distance round the corner.
gps speed indicators can only be accurate if the sample time is extremely fast, or on a long straight and level road. (perhaps thats why you cant use them for iva...)


big-vee-twin - 5/12/16 at 08:33 PM

They will do you for the 33 in a 30, ask me how I know!


Nickp - 5/12/16 at 08:37 PM

quote:
Originally posted by big-vee-twin
They will do you for the 33 in a 30, ask me how I know!


Ok, how do you know?


craig1410 - 5/12/16 at 08:38 PM

@gremlin1234 The same is true of LIDAR or radar speed guns. They will always under read unless you are travelling directly toward the device. Any sideways velocity component will be lost.

[Edited on 5/12/2016 by craig1410]


Ugg10 - 5/12/16 at 10:45 PM

Not based on any evidence but unless you can produce a calibration certificate for the gps in your car I suspect any evidence will not be worth a jot.

As others have said, accept it, do the naughty boy course and hopefully learn a few things in the process.


Nickp - 6/12/16 at 06:57 AM

quote:
Originally posted by Ugg10
Not based on any evidence but unless you can produce a calibration certificate for the gps in your car I suspect any evidence will not be worth a jot.

As others have said, accept it, do the naughty boy course and hopefully learn a few things in the process.


Learn a few things? Hmmm, we'll see


motorcycle_mayhem - 6/12/16 at 10:02 AM

Just before he died, my father-in-law (80's) was extremely upset by a prosecution for doing 32 in a village 30 zone.
The circumstances were the 'usual' for that age group, he only drove the car during the day, in ideal weather, outside of the mayhem time zones, one end of the village to the other. His only ever 'offence' in his life.

I thought I'd get it annulled with the 10% guidance, given the analogue speedo on a Mk1 Mundaneo. But no.


nick205 - 6/12/16 at 10:06 AM

quote:
Originally posted by SPYDER
Surely its a fair cop anyway. I can't see what can possibly be gained.
You'll be offered a Speed Awareness Course. Take it and keep your clean licence.



My thoughts too.

You'll more than likely be offered a "speed awareness" course with no points. Pay the fine, do the course (they're not that bad really) and move on. I'd have thought if you try and contest it you'll lose out.


Matt21 - 6/12/16 at 10:23 AM

You were so close to beating James May too!


loggyboy - 6/12/16 at 10:36 AM

quote:
Originally posted by Matt21
You were so close to beating James May too!


Pretty sure I have a couple that beat him, ive been done for 35 and 36.


craig1410 - 6/12/16 at 10:43 AM

Just put this down to experience and try to improve your speed(trap) awareness!

I had a clean license for about 12 years and then managed to get a speeding fine for doing 72 in a 50 on a motorway section which has no apparent need to be a 50MPH section. I actually asked the police why this section was 50MPH and they told me it is because, just after it was built (perhaps 15 years ago now) some locals used to still walk home using a route which required them to walk across the motorway and the reduced limit was to give them more of a chance to get across safely! I could barely contain myself at this explanation! What happened to letting Darwin decide???

Then about 6 months later I got a TS10 traffic light ticket for going through a supposed red light which was definitely not red and had only just turned to amber as I went past the point of no return. I was extremely annoyed at this as it was (hand on heart) not fair but after reviewing the law on traffic lights, there was a snowball's chance in hell of contesting it against the word of no less then 3 police officers in the traffic car. Even going through an amber light is an offence unless you can prove it was not safe to stop as you may be aware.

So from 0 points to 6 in 6 months was not great! Anyway, that was in 2012 and 2013 and I'm back to a clean license again and long may that continue.


loggyboy - 6/12/16 at 11:18 AM

I havent had a clean license since 1997
Even worse when you consider I passed in 1996.

[Edited on 6-12-16 by loggyboy]


coyoteboy - 6/12/16 at 12:59 PM

If you wanted to do this you'd have to get independent verification of the GPS accuracy (test lab) and have sufficient log frequency that you could not logically deviate within that log period. How much are you willing to spend?

Given the power and mass of your vehicle you could put bounds on your max and min possible speed in the time between the log points, and you've got a +/- on the speed in the first place from it's measurement points. There's a damn good chance you couldn't prove you were not at 36 for example.

[Edited on 6/12/16 by coyoteboy]


nick205 - 6/12/16 at 04:30 PM

quote:
Originally posted by craig1410
Just put this down to experience and try to improve your speed(trap) awareness!

I had a clean license for about 12 years and then managed to get a speeding fine for doing 72 in a 50 on a motorway section which has no apparent need to be a 50MPH section. I actually asked the police why this section was 50MPH and they told me it is because, just after it was built (perhaps 15 years ago now) some locals used to still walk home using a route which required them to walk across the motorway and the reduced limit was to give them more of a chance to get across safely! I could barely contain myself at this explanation! What happened to letting Darwin decide???

Then about 6 months later I got a TS10 traffic light ticket for going through a supposed red light which was definitely not red and had only just turned to amber as I went past the point of no return. I was extremely annoyed at this as it was (hand on heart) not fair but after reviewing the law on traffic lights, there was a snowball's chance in hell of contesting it against the word of no less then 3 police officers in the traffic car. Even going through an amber light is an offence unless you can prove it was not safe to stop as you may be aware.

So from 0 points to 6 in 6 months was not great! Anyway, that was in 2012 and 2013 and I'm back to a clean license again and long may that continue.



Not got a license at the moment, but some years ago I reached 11 points in speeding offences (you lose your license at 12 points). I drove like a vicar for some time thereafter.

I've never argued with or contested offences - doesn't seem worth the effort, likely cost and almost certain fail to me.


Ivan - 7/12/16 at 02:43 PM

This is in South Africa:

I got a speeding fine for doing 89kph in a 80 zone - a check on my GPS track showed that I was nowhere near the camera at the exact time shown by the camera (about 2km away) and was doing 66 in a 60 zone. I didn't mention the location issue but sent them the piece of the GPS track for that time and they withdrew the case.