Accuracy of GoSafe vans

Ah_Yeah

I know these threads have been done to death but I can't find many recent ones. I was wondering if anyone knows how accurate the GoSafe Vans are? I passed one doing no more than a few KM over (I glanced at the speedo hand and it was about a mm over the 100 mark), but I'm worried I'll get a letter in the post.

I got points for speeding last year and I well and truly learned my lesson, I'm constantly checking the speedo!

I drive past a few of the radar controlled speed limit signs every day and the speed on those vs my speedo shows about 3km in the difference in a 50 zone, but I'm not sure if that's reflective of the accuracy of the GoSafe Vans.

_Brian

You'll be fine.




Maybe!

Ah_Yeah

_Brian wrote: »

You'll be fine.




Maybe!

If I get a letter I'll send the fine your way so

I probably wouldn't worry only I already got points last year and I have been so careful ever since, I really couldn't bear to have any more on my licence!

Atlantic Dawn

If you haven't adjusted the tyre or wheel size from original spec your speedo should over compensate by about 10%, you should be fine.

ironclaw

Starting out, many years ago, I believe the tolerance was about 6km/h. So in a 100km/h zone, a reading of 106km/h would have you snapped. This dropped about 18 months (or more) ago to 3km/h, or there abouts. So 103km/h and you'd be snapped.

However as Atlantic Dawn pointed out, this is your true speed. Your speedometer speed is quite different. EU directives mean that no speedo, on stock tyres etc, can ever report a speed higher than you are actually travelling, it must always be that speed or lower. Most cars, depending on how fast you are travelling, will under-read by between 5% and 10% of true speed. This causes endless confusion on motorways as people can't understand why they are being passed when they are doing 120km/h.

In conclusion, at worst, if your speedo said you were doing 103km/h, you were probably doing closer to ~98km/h. Or the other way around, to stand a chance of even standing on the line of getting a ticket, you'd want to be showing 110km/h on your speedo as you passed the van.

And in case anyone searches for this:

You must be about 2.5 times the width of the road away from the rear of the van to receive a ticket. No vans can't see over hedges or through walls. Nor do they operate like Tom Cruise in Minority Report.

CeilingFly

Atlantic Dawn wrote: »

If you haven't adjusted the tyre or wheel size from original spec your speedo should over compensate by about 10%, you should be fine.

about 20 years ago that would be correct, but speedometer accuracy is much improved these days and will err by very little and certainly not by 10%

GoSafe laser systems are very accurate, but the fine is not automatic. A garda checks all the images and will usually allow some leeway.

grogi

CeilingFly wrote: »

about 20 years ago that would be correct, but speedometer accuracy is much improved these days and will err by very little and certainly not by 10%

GoSafe laser systems are very accurate, but the fine is not automatic. A garda checks all the images and will usually allow some leeway.

Type approval rules are clear about that http://eur-lex.europa.eu/legal-content/EN/TXT/?uri=CELEX:42010X0513(03)

The speed indicated shall not be less than the true speed of the vehicle. At the test speeds specified in paragraph 5.2.5 above, there shall be the following relationship between the speed displayed (V1) and the true speed (V2).

0 ≤ (V1 – V2) ≤ 0,1 V2 + 4 km/h

grogi

OSI wrote: »

I haven't driven a car in 10 years that's been more than 1km/h off the GPS reading below 130+

ALL my cars have been off - from 3% to 10%.

Bored Accountant

OSI wrote: »

I haven't driven a car in 10 years that's been more than 1km/h off the GPS reading below 130+

When I have the Sat Nav on or GPS speedo on my phone, my speedo is appox 7% out and this has been fairly constant over past 2 or 3 cars I had.

In comparison, when I was in the states where I bought the Sat Nav, the speedo was bang on matching the speed on the sat nav.

Ninjavampire

There is a school on the main road near me that has a 'slow down' sign that reads your speed. That seems to read about 1 - 3 km lower than my speedometer (never higher!) and I assume it uses similar technology to the vans! I drive an unmodded 07 Renault.

Vicxas

Ninjavampire wrote: »

There is a school on the main road near me that has a 'slow down' sign that reads your speed. That seems to read about 1 - 3 km lower than my speedometer (never higher!) and I assume it uses similar technology to the vans! I drive an unmodded 07 Renault.

Same,

There's one of these at the back of Phoenix Park and they always read my speed doing around 55-56km/h when my speedometer is sitting on 60

Henry Ford III

I've had loads of brand new cars over the years. Speedos are invariably optimistic. Usually c. 5%.

Add in a small bit of discretion and anything under 110kph indicated is good I reckon.

grogi

OSI wrote: »

Going by your own link above, anything showing more than 105km/h at 100km/h true speed would fail type approval, which is only 5%.

No, the difference needs to be smaller or equal than 10% plus 4kmh. So at
- 100kmh it can show 114kmh at still be ok (14%)
- 50kmh it can show 59 at be ok (18%)

Del2005

OSI wrote: »

I haven't driven a car in 10 years that's been more than 1km/h off the GPS reading below 130+

I drove with a phone and stand alone GPS, both had different speeds showing so don't think that GPS is accurate. It's designed not to be and struggles with slopes.

To find out how inaccurate your speedo is get an OBD2 reader and software and drive, or some cars can display diagnostic mode on the dash. Your car knows exactly what speed you are doing it just can't tell you.

grogi

Del2005 wrote: »

I drove with a phone and stand alone GPS, both had different speeds showing so don't think that GPS is accurate. It's designed not to be and struggles with slopes.

To find out how inaccurate your speedo is get an OBD2 reader and software and drive, or some cars can display diagnostic mode on the dash. Your car knows exactly what speed you are doing it just can't tell you.

But when reading from OBD2, you're discarding inaccuracies in wheel/tyre sizes.

The same car can be approved on different size of tyres, for instance 205/55/R16 and 225/45/R17. Differences aren't huge - within 1%. But incorrect tyre pressure adds to the error too.

TheChizler

Del2005 wrote: »

I drove with a phone and stand alone GPS, both had different speeds showing so don't think that GPS is accurate. It's designed not to be and struggles with slopes.

On a flat straight at a constant speed your GPS derived speed will be spot on. It's absolute-position dependent and positioning inaccuracies will cancel out over multiple readings. Your speedo depends on so many variables; tyre pressure, temperature, tyre density, electronic component variation and non-linearities, you can calibrate to account for most of the variation but you can't get close to the accuracy of position derived speed in a straight line.

It does have the advantage that it's continuous, where GPS depends on discrete samples, so will deal better with change in velocity.

Del2005

TheChizler wrote: »

On a flat straight at a constant speed your GPS derived speed will be spot on. It's absolute-position dependent and positioning inaccuracies will cancel out over multiple readings. Your speedo depends on so many variables; tyre pressure, temperature, tyre density, electronic component variation and non-linearities, you can calibrate to account for most of the variation but you can't get close to the accuracy of position derived speed in a straight line.

It does have the advantage that it's continuous, where GPS depends on discrete samples, so will deal better with change in velocity.

So why did I have 2 different speeds? Both couldn't be spot on.

ironclaw

Ninjavampire wrote: »

There is a school on the main road near me that has a 'slow down' sign that reads your speed. That seems to read about 1 - 3 km lower than my speedometer (never higher!) and I assume it uses similar technology to the vans! I drive an unmodded 07 Renault.

Vicxas wrote: »

Same,

There's one of these at the back of Phoenix Park and they always read my speed doing around 55-56km/h when my speedometer is sitting on 60

Just to add to the thread, these signs are no where near comparable in terms of accuracy to the GoSafe vans.

As regards GPS, especially if using a phone, won't be very accurate. The sample rate is variable and the receiver chip-set designed for consumer use. For example, you don't need to know within one foot of where you are, its enough to know to within 3 to 10m most times for navigation. Likewise, a developer can set the same rate and accuracy they are happy with. You generally trade off with a low sample rate and average, again you don't need huge precision. This keeps the App fast and the power drain low as you ain't doing a sample and calculation every few ms. Same applys for dash mounted units.

If you really want to know your speed, the only way is with track timer rated GPS kit or a laser gun.

Henry Ford III

Has the rotation of the earth been factored in here lads?

Victor

Ah_Yeah wrote: »

Accuracy of GoSafe vans

Better than pretty much any speedometer.

Del2005 wrote: »

So why did I have 2 different speeds? Both couldn't be spot on.

How much was the difference?

Ah_Yeah

I seem to have started a debate

Is the general consensus that a few km over on my speedo should be OK on the GoSafe? I obviously will only truly know if I get a letter in the post!

Ninjavampire

Ah_Yeah wrote: »

I seem to have started a debate

Is the general consensus that a few km over on my speedo should be OK on the GoSafe? I obviously will only truly know if I get a letter in the post!

I was in the exact same situation the week I got my full licence. Went past a speedvan doing 61 on my speedometer in a 60km zone and nothing ever came of it.

Ah_Yeah

Ninjavampire wrote: »

I was in the exact same situation the week I got my full licence. Went past a speedvan doing 61 on my speedometer in a 60km zone and nothing ever came of it.

At 61km in a 60 zone I would definitely be confident nothing would come of it. My speedo is not digital so it's hard to guess what exact speed I was doing but I'd say 103/104 at the max, but could definitely have been less.

I'll just have to wait!

Rubberchikken

why don't people just drive slightly or even more below the speed LIMIT? not complicated unlike all the endless deductions etc in the previous posts which are exhausting imho:)

Bored Accountant

Rubberchikken wrote: »

why don't people just drive slightly or even more below the speed LIMIT? not complicated unlike all the endless deductions etc in the previous posts which are exhausting imho:)

OR

Just do 55km, 66km, 108km, 130km and still be sure of being under all the speedlimits. doesn't take a massive amount of deductions.

Ah_Yeah

Rubberchikken wrote: »

why don't people just drive slightly or even more below the speed LIMIT? not complicated unlike all the endless deductions etc in the previous posts which are exhausting imho:)

I do - as I mentioned, I got points last year and as a result have been very careful. It is easy for the speedo to slip slightly above the speed limit every now and then, and is more dangerous IMO to be constantly staring at the speedo. I am conscious to check the speedo and not (what I constitute as) excessively speed, but the speedo does slip above every now and again and I correct.

Bored Accountant

Ah_Yeah wrote: »

is more dangerous IMO to be constantly staring at the speedo. I am conscious to check the speedo and not (what I constitute as) excessively speed, but the speedo does slip above every now and again and I correct.

one benefit of having the speed limiter on the car. can set it to exactly the max speed I want to be able to do. no need to worry then about going slightly over.

Ah_Yeah

Bored Accountant wrote: »

one benefit of having the speed limiter on the car. can set it to exactly the max speed I want to be able to do. no need to worry then about going slightly over.

Is this not illegal?

I can use Cruise Control to do the same I guess!

Del2005

Victor wrote: »

How much was the difference?

It was a good while ago but was a few km, at least enough to get points if the previous poster is correct and they've reduced the tolerance of the speed vans.

GM228

Bored Accountant wrote: »

one benefit of having the speed limiter on the car. can set it to exactly the max speed I want to be able to do. no need to worry then about going slightly over.

Depending on the road layout, even with a speed limiter you can go well more than "slightly over" the limit.

Ah_Yeah wrote: »

Is this not illegal?

I can use Cruise Control to do the same I guess!

Not illegal, all trucks and coaches have them fitted and many modern cars which have CC also have speed limiters.

Del2005

Rubberchikken wrote: »

why don't people just drive slightly or even more below the speed LIMIT? not complicated unlike all the endless deductions etc in the previous posts which are exhausting imho:)

Because I'm a do as you do not say person and in all my interactions with the RSA I had to drive at the limit or else I got penalised for progression, back in the old imperial days you had to drive over the limit during the test.

368100

ironclaw wrote: »

Starting out, many years ago, I believe the tolerance was about 6km/h. So in a 100km/h zone, a reading of 106km/h would have you snapped. This dropped about 18 months (or more) ago to 3km/h, or there abouts. So 103km/h and you'd be snapped.

However as Atlantic Dawn pointed out, this is your true speed. Your speedometer speed is quite different. EU directives mean that no speedo, on stock tyres etc, can ever report a speed higher than you are actually travelling, it must always be that speed or lower. Most cars, depending on how fast you are travelling, will under-read by between 5% and 10% of true speed. This causes endless confusion on motorways as people can't understand why they are being passed when they are doing 120km/h.

In conclusion, at worst, if your speedo said you were doing 103km/h, you were probably doing closer to ~98km/h. Or the other way around, to stand a chance of even standing on the line of getting a ticket, you'd want to be showing 110km/h on your speedo as you passed the van.

And in case anyone searches for this:

You must be about 2.5 times the width of the road away from the rear of the van to receive a ticket. No vans can't see over hedges or through walls. Nor do they operate like Tom Cruise in Minority Report.

Ha ha....or they just think they're speeding

Bored Accountant

Ah_Yeah wrote: »

Is this not illegal?

I can use Cruise Control to do the same I guess!

My cruise control - I can set to maintain a set speed, or not to exceed a set speed whereby I control the accelerator/brake.

deandean

A big issue here is, what speed do you get a ticket at? It seems a closely guarded secret. The Gosafe van drivers wouldn't even tell a judge in a recent court case.
A pal of mine got a ticket for 56 in a 50 zone (in Dublin - Garda van).
Perhaps other posters could post up what speeds they got tickets at.

mikeecho

deandean wrote: »

A big issue here is, what speed do you get a ticket at? It seems a closely guarded secret. The Gosafe van drivers wouldn't even tell a judge in a recent court case.
A pal of mine got a ticket for 56 in a 50 zone (in Dublin - Garda van).
Perhaps other posters could post up what speeds they got tickets at.

It has been stated here on boards, but then you get the usual "source ?"

9km/h and gosafe will ticket you.
8km/h and gosafe won't ticket you.

The robot vans run by the Garda , .. well its up to the Garda inside the van what tolerance he personally allows.

TheChizler

Del2005 wrote: »

So why did I have 2 different speeds? Both couldn't be spot on.

You were possibly changing speeds/had just changed speed, going round a bend, different sampling rate on the receivers, different method of calculating speed (instantaneous, running average etc.). On the straight and flat at a constant speed they should be the same.

Which of course is not very useful when driving a car, I was only addressing the suggestion that GPS derived speed is inherently inaccurate. Used properly it can be incredibly accurate.

Ah_Yeah

mikeecho wrote: »

It has been stated here on boards, but then you get the usual "source ?"

9km/h and gosafe will ticket you.
8km/h and gosafe won't ticket you.

The robot vans run by the Garda , .. well its up to the Garda inside the van what tolerance he personally allows.

This is not true as I received a ticket for doing 107 in a 100 zone last year.

Hence the worry!

CeilingFly

mikeecho wrote: »

It has been stated here on boards, but then you get the usual "source ?"

9km/h and gosafe will ticket you.
8km/h and gosafe won't ticket you.

The robot vans run by the Garda , .. well its up to the Garda inside the van what tolerance he personally allows.

Incorrect, on N7 at kill a colleague got ticket for 105km - I had to see it to believe it. She rang Thurles and the only option was to go to court, so she paid it.

Del2005

TheChizler wrote: »

You were possibly changing speeds/had just changed speed, going round a bend, different sampling rate on the receivers, different method of calculating speed (instantaneous, running average etc.). On the straight and flat at a constant speed they should be the same.

Which of course is not very useful when driving a car, I was only addressing the suggestion that GPS derived speed is inherently inaccurate. Used properly it can be incredibly accurate.

I was on the Naas road passing Browns Barn at an indicated 100 on the speedo, not many corners but a bit of a hill.

mikeecho

Ah_Yeah wrote: »

This is not true as I received a ticket for doing 107 in a 100 zone last year.

Hence the worry!

Are you sure it was a gosafe, and not a Garda van?

I was told within the last 5months by a gosafe employee of the 9km limit.

Ah_Yeah

mikeecho wrote: »

Are you sure it was a gosafe, and not a Garda van?

I was told within the last 5months by a gosafe employee of the 9km limit.

Yep! I remember passing it and sweating for weeks worrying (like I am now), and then getting the letter! I think I was doing about 110 on the speedo and was recorded at 107. Different car to now though so can't say that it's the same number of km out on this one.

Unless it has changed as this was almost 18 months ago.

What else did they tell you? Share the wisdom

mikeecho

Ah_Yeah wrote: »

Yep! I remember passing it and sweating for weeks worrying (like I am now), and then getting the letter! I think I was doing about 110 on the speedo and was recorded at 107. Different car to now though so can't say that it's the same number of km out on this one.

Unless it has changed as this was almost 18 months ago.

Well, considering that their detection rate is less than 2 per hr.

I wouldn't be surprised if they have further reduced the tolerance, in order to make the system justify its existence.

At this point, everyone knows the locations of the vans that are on their regular commute, and combine that with their short range, you'd be very unlucky/unobservant to be caught.

Ah_Yeah

mikeecho wrote: »

Well, considering that their detection rate is less than 2 per hr.

I wouldn't be surprised if they have further reduced the tolerance, in order to make the system justify its existence.

At this point, everyone knows the locations of the vans that are on their regular commute, and combine that with their short range, you'd be very unlucky/unobservant to be caught.

Well I think if I get a letter I'll definitely be unlucky as I monitor the speedo like my life depended on it!

68 lost souls

I use Waze to get GPS speed on iPhone 6s, set cruise control to the limit +-1kmh every time I drive now (circa 800-1000km a week, 14700km since January 1st) and have passed GOSafe and Garda vans without receiving tickets. Car (golf mkv 205/55/r16 at 2.4 in the front and 2.2 in the back) normally indicated for example 128kmh at 120kmh

Received points 3 years ago doing 62 in a 50 (speed changed from 50 to 100 a couple of meters further on) and since then have been super careful.

sdanseo

Rubberchikken wrote: »

why don't people just drive slightly or even more below the speed LIMIT? not complicated unlike all the endless deductions etc in the previous posts which are exhausting imho:)

Because the vast majority of speed limits on main or arterial routes are baselessly and unreasonably low.

I set cruise control to speed limit + 2-4km/h. Based on GPS that means my real speed is on the button and doesn't leave the chance of leeway, tolerance or other interpretation. For the sacrifice of an additional 3-4km/h, it's worth not worrying about points and a fine.

mikeecho

Ah_Yeah wrote: »

What else did they tell you? Share the wisdom

Anything else, is available on the inter web by looking at manufacturer specs.

All have been posted on boards already.

dev100

mikeecho wrote:

I wouldn't be surprised if they have further reduced the tolerance, in order to make the system justify its existence.

That's why you see go safe vans parked up on motor way gardai observation points nice handy easy pickings the state actually losses money hiring go safe it's not self funding and the only way to do that is to increase fine prices and lower speed limits and and increase detention areas . Recently there's one parking on the motor way on the M11 he can't drive onto to garda ops position and actually parks on the M11hard shoulder which is a health and safety issue plus there's no camera signs up either but I've been told they also do survey work also .... You couldn't pick a straighter and safe stretch of road for the sheriffs to park up.

CeilingFly wrote:

Incorrect, on N7 at kill a colleague got ticket for 105km - I had to see it to believe it. She rang Thurles and the only option was to go to court, so she paid it.

Ah_Yeah wrote:

This is not true as I received a ticket for doing 107 in a 100 zone last year.

Generally if you were done at that speed usually you will be going a higher speed if you had looked at your speedo at the time of getting caught. I've passed go safe and gatso vans doing say 5km to 7km over the limit and never got done. If you see the snipers out with the hair dryers they don't go near you if you are a few K over the limit.

Ah_Yeah

dev100 wrote: »

That's why you see go safe vans parked up on motor way gardai observation points nice handy easy pickings the state actually losses money hiring go safe it's not self funding and the only way to do that is to increase fine prices and lower speed limits and and increase detention areas . Recently there's one parking on the motor way on the M11 he can't drive onto to garda ops position and actually parks on the M11hard shoulder which is a health and safety issue plus there's no camera signs up either but I've been told they also do survey work also .... You couldn't pick a straighter and safe stretch of road for the sheriffs to park up.

I thought they weren't allowed on motorways, especially hard shoulders? Has that changed?

Cordell

130 on the speedo, 125 on the hairdryer New car with factory tyres.
All cars will add some correction to the measured speed, and on most cars you should be able to read the measured speed with any cheap ODB dongle.

sdanseo

Ah_Yeah wrote: »

I thought they weren't allowed on motorways, especially hard shoulders? Has that changed?

They can and do park on the "Garda Only" ramps on the M1.
I would imagine being authorised/directed by AGS to park there is the same as being an Garda vehicle legally.

Ah_Yeah

sdanseo wrote: »

They can and do park on the "Garda Only" ramps on the M1.
I would imagine being authorised/directed by AGS to park there is the same as being an Garda vehicle legally.

Ah right. I better keep a more vigilant eye on the M11 so!