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AdrianEagle
Original Poster
84 posts
89 months
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StressedDave said: Actually C&U these days states +10%+4 km/h/-0%, so the maximum error at 30mph could be 18% overread (i.e. 36ish mph rather than 30 mph). There's a bit more of an error in SVA rules allowing for 10%+6.25mph overread. What Construction and Use Regulations state and what one actually gets are not always the same thing. Once again accuracy could match C & U Regs when the vehicle is brand new, but once you get a bit of wear on the tyres and the rolling circumference reduces, an error is introduced and gradually increases due to the additional revolutions of the wheels to cover the same distance. Add a slight underpressure as tyres deflate themselves rather than the reverse and the error is compounded. If you wish I'll give you the Maths, but have resisted the temptation, so as not to risk boring everyone! You can, I'm sure work it out yourself. Unfortunately we have moved away from my comment that RoSPA, through Mr Smalley, condone the use of inaccurate instruments. p.s. To Bobmalcs who PM'd me. Sorry can't help - suggest you start at Hendon.
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MC Bodge
3,795 posts
44 months
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Does this win the prize for the most tedious thread? 
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AdrianEagle
Original Poster
84 posts
89 months
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Probably the answer to that is a great big "YES!" Please send prize to any worthwhile and appropriate charity of your choice!
But then again there any many awful threads on this Forum as there are on any Forum one cares to visit! You can be the adjudicator and dish out the prizes.
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_Neal_
1,026 posts
88 months
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So to summarise, you've given up being a Rospa tutor (and imparting your knowledge and experience to keen-to-learn "non-advanced" drivers) because you disagree with the Chief Examiner as to which device drivers should use to assess their speed?
When you were teaching, would you carry a sat nav with you, stick it on the dash and tell the student to drive to the speed shown on the GPS rather than that shown on the car's speedo?
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AdrianEagle
Original Poster
84 posts
89 months
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_Neal_ said: So to summarise, you've given up being a Rospa tutor (and imparting your knowledge and experience to keen-to-learn "non-advanced" drivers) because you disagree with the Chief Examiner as to which device drivers should use to assess their speed?
When you were teaching, would you carry a sat nav with you, stick it on the dash and tell the student to drive to the speed shown on the GPS rather than that shown on the car's speedo? NO is the quick answer to the first part. I believe that we must absorb and use new techology especially when it is in the interests of safety. Accurate speed registration is an aid to safer driving. I am not prevented from assisting others to improve their driving skills by leaving RoSPA, and if a driver had the use of Sat Nav I would suggest it be used in conjunction with the OEM instruments. Sat Navs are now in common use but I would warn drivers that the reliance on a Sat Nav is taboo when taking a RoSPA test. I am sure most of us will have noticed that new cars are generally fitted with Sat Navs as standard, or there is a place for one to be fitted as an extra. I wonder how long it will be before the speedo is linked to the Sat Nav instead of being a seperate instrument? The Government are already well ahead with a road charging scheme that will rely completely on such technology and not only will they be able to charge for use of the road they will probably also be able to accurately tell your speed! Watch out for NIP's coming through your letter box. As a point of interest the I.A.M. and RoSPA do not have Instructors. Both organisations are clear that they do not instruct people and that they have a passive role. I.A.M. refer to theirs as "Observers" and RoSPA as "Tutors". So "teaching" does not come into the equation despite the term of Tutor.
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_Neal_
1,026 posts
88 months
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AdrianEagle said: As a point of interest the I.A.M. and RoSPA do not have Instructors. Both organisations are clear that they do not instruct people and that they have a passive role. I.A.M. refer to theirs as "Observers" and RoSPA as "Tutors". So "teaching" does not come into the equation despite the term of Tutor. You are right (and I did use the word tutor deliberately) but the "observer"/"tutor" role as being passive, not active is, in my view, for the IAM's/RoSPA's own protection - they clearly do instruct, albeit on a unpaid voluntary basis, but don't want to get embroiled in some kind of "he told me to do it and I crashed" lawsuit. Just my 2 pence though  AdrianEagle said: NO is the quick answer to the first part. I believe that we must absorb and use new techology especially when it is in the interests of safety. Accurate speed registration is an aid to safer driving. Of course, but you've excluded yourself from being part of an organisation that provides a forum within which you can pass your skills on. Seems like you're cutting off your nose to spite your face. As to your point, it'd be much safer, surely, if people drove with better observation and other "advanced" skills than mindlessly sticking exactly to an empirically-verified speed limit? You may be right that it's a safety issue if car speedos widely underread by 10-15%, so people were unwittingly driving around much faster than they thought they were. But they don't, and people aren't.
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AdrianEagle
Original Poster
84 posts
89 months
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_Neal_ said: Of course, but you've excluded yourself from being part of an organisation that provides a forum within which you can pass your skills on. Seems like you're cutting off your nose to spite your face.
As to your point, it'd be much safer, surely, if people drove with better observation and other "advanced" skills than mindlessly sticking exactly to an empirically-verified speed limit? You may be right that it's a safety issue if car speedos widely underread by 10-15%, so people were unwittingly driving around much faster than they thought they were. But they don't, and people aren't.
I think along the line we agree on the major point - it would be better if everyone drove according to the whole Advanced Driving System - but they don't, and I know on some occasions I don't. But I try to save my youthful exhuberance for the occasions where I can drive at speed, in safety, without causing any hazardous situations for myself or others. The track is obviously the best place. There is no "cutting off noses" - at 75 I am fast approaching the time when I will probably have to give up assisting others and concentrate on ensuring that I do not become a problem to other road users myself. In the meantime I will continue to enjoy my motoring, the Car Club, arranging Meets and partaking in discussion Forums such as this. I can live without RoSPA and I am sure that RoSPA will survive without me!
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Mr Grayson
136 posts
44 months
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Maybe part of Bob's objection was to people diverting their attention from the fixed instruments to a windscreen mounted device and back again, just to check speed. The law prevents us from playing with mobile phones while on the move, and there could be an argument that SatNavs are just as distracting. It seems there's also the slight implication in your post that you are looking for the maximum possible leeway for legal purposes (but that may just be a colouring added by subsequent posters), which strikes a slightly jarring note. Either way, as we are all aware, limits are not targets. A lot of the time the limit will be inappropriate because of hazard density.
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7mike
2,053 posts
62 months
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_Neal_
1,026 posts
88 months
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AdrianEagle said: I think along the line we agree on the major point - it would be better if everyone drove according to the whole Advanced Driving System - but they don't, and I know on some occasions I don't. But I try to save my youthful exhuberance for the occasions where I can drive at speed, in safety, without causing any hazardous situations for myself or others. The track is obviously the best place.
There is no "cutting off noses" - at 75 I am fast approaching the time when I will probably have to give up assisting others and concentrate on ensuring that I do not become a problem to other road users myself. In the meantime I will continue to enjoy my motoring, the Car Club, arranging Meets and partaking in discussion Forums such as this. I can live without RoSPA and I am sure that RoSPA will survive without me! Good post, and yes, we do agree! The important thing is that we enjoy our motoring, and if RoSPA wasn't fitting in with that for you, you were absolutely right to ditch it.
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AdrianEagle
Original Poster
84 posts
89 months
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7mike said: Not quite the same but very interesting all the same.
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Starfighter
1,149 posts
47 months
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[Off topic] _Neal_ said: AdrianEagle said: As a point of interest the I.A.M. and RoSPA do not have Instructors. Both organisations are clear that they do not instruct people and that they have a passive role. I.A.M. refer to theirs as "Observers" and RoSPA as "Tutors". So "teaching" does not come into the equation despite the term of Tutor. You are right (and I did use the word tutor deliberately) but the "observer"/"tutor" role as being passive, not active is, in my view, for the IAM's/RoSPA's own protection - they clearly do instruct, albeit on a unpaid voluntary basis, but don't want to get embroiled in some kind of "he told me to do it and I crashed" lawsuit. Just my 2 pence though It's all symantics to keep the DSA type "instructors" happy. Every observed drive I did involved teaching to some degree and in many cases in detail. Every drive was also acompanied with a disclaimer along the lines of "This is your car, you are driving. It is up to you to keep us safe so feel free to ignor what I am saying and just drive the car." [back on Topic] My satnav speed is rather small numbers it takes more time to focus and read this than read the needle position. This may be part of Bob's reasoning. That and the programming logic for satnavs assumes the maps to be 2D at sea level so any deviation from a straight line steady speed down Blackpool sea front and there will be errors.
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AdrianEagle
Original Poster
84 posts
89 months
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Starfighter said: My satnav speed is rather small numbers it takes more time to focus and read this than read the needle position. This may be part of Bob's reasoning. That and the programming logic for satnavs assumes the maps to be 2D at sea level so any deviation from a straight line steady speed down Blackpool sea front and there will be errors. My SatNav has an option to be used for "Safety" and in this mode full size numerals are shown. Even in "Navigation" mode the speed element is still easily readable. Your final assumption , whilst true for many units, is in fact incorrect, as instruments are available that compensate for height. However, as none of us are likey to be driving over Everest, or even Snowdon, the height error is quite negligible and can virtually be ignored.
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Starfighter
1,149 posts
47 months
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AdrianEagle said: My SatNav has an option to be used for "Safety" and in this mode full size numerals are shown. Even in "Navigation" mode the speed element is still easily readable.
Your final assumption , whilst true for many units, is in fact incorrect, as instruments are available that compensate for height. However, as none of us are likey to be driving over Everest, or even Snowdon, the height error is quite negligible and can virtually be ignored. Agreed - the assumptions may be minor but they are there and does call in to question the assertion from many that a highstreet satnav is 10.000% accurate under all circumstance. They are not. There may be a difference btween the vehicle speedo and a GPS based system but these are small and the difference becomes relatively insignificant over the course of most people's daily run where for most of the drive the speed to determined by the circumstances rather than the posted limit. My old instructor's comment was "top wack on a good day"
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AdrianEagle
Original Poster
84 posts
89 months
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Starfighter said: Agreed - the assumptions may be minor but they are there and does call in to question the assertion from many that a highstreet satnav is 10.000% accurate under all circumstance. They are not. I presume the position of the decimal point is purely a typing error! :-)
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Starfighter
1,149 posts
47 months
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AdrianEagle said: I presume the position of the decimal point is purely a typing error! :-) This is correct. This is me.... 
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hms
116 posts
67 months
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I have no views on this, but could the reason be that as the speedo underreads, if you do have the 'odd' moment of exceeding the speed, limit by the speedo, you are still under the actual limit as measured by the police,, speed camera, gps etc?
H
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AdrianEagle
Original Poster
84 posts
89 months
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hms said: I have no views on this, but could the reason be that as the speedo underreads, if you do have the 'odd' moment of exceeding the speed, limit by the speedo, you are still under the actual limit as measured by the police,, speed camera, gps etc?
H I think you will find that most speedos actually overread, i.e. at 30 mph actual speed, my dial type speedo reads around 25-29. As there are no numerals between the 20 and 40 marks one has to guess anyway! One more arguement for using a GPS! :-)
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Pontoneer
2,551 posts
55 months
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Are you sure ? That would mean that at an indicated 30 you would actually be going faster .
My understanding was that speedometers had , by law , to err on the side of safety such that you would never find yourself traveling faster than they indicate .
Without looking up the regs , isn't the allowable margin for error 10% but only over reading so that at a true 30 it might show 33 ; or at an indicated 30 you might be doing 27-ish . The comparison I mentioned in an earlier post between my speedometer and my 'accurate ?' satnav would bear this out , even though my observed differences were marginal , the satnav ALWAYS indicates one or two mph less than the speedometer , once a steady speed has been maintained for a period of time .
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powerstroke
1,719 posts
29 months
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AdrianEagle said: One of the main attributes of an Advanced Driver is to make Progress and use the various speed limits one encounters to the best advantage, in safety of course. In other words, do 30 in a 30 limit, 40 in a 40, 60 in a 60 etc.
In a recent exchange of correspondence with Bob Smalley, the CHIEF EXAMINER of RoSPA Drivers and Riders, he stated that he would prefer for a driver to use a known inaccurate OEM speedometer to using an after market fitted electronic device that has been proved to be 99.9% accurate.
How on Earth can a person in such a position disregard and condemn the fitting of an accurate device over the inaccurate OEM equipment that has a different percentage of error over its whole range? Not the sort of attitude to encourage people to give the RoSPA test anything but a very wide berth! I know which I prefer and accordingly have given up my Gold RoSPA Award and my Tutor's position. The guy seems to be a pedatic dick.. sorry but realy a speed limit is a guide as is your speedometer,surely we should be driving to the conditions within the posted limits on the road ..most limits are b  ks anyway!! for instance , plenty of 30s where 30 would be dangerous and others where 40 or 50 would be more aproprate but the law is the law ...
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