Safe Speed Forums

Okay, but it might actually have been the case that he was looking at a different table, as there is one that has a 19% figure.



Because there is a lot of traffic and it is fast moving.



The numbers who drove past the accident would be very small I would have thought compared to the number of people who use the road. As for radio reports or local TV news, in my experience they are only ever give very brief mentions.



'Bias on selection' but I have been saying that there wasn't any in this case.



Okay, but for all we know it could well be the case that other factors have only a very small contribution.



Well it would be good if their study was reviewed. But I don't accept that the 10% figure poses a real risk of being optimistic, other than by a very small amount.



The same place that the 10% figure comes from.



And this is why I don't like arguing statistics because they can get very complicated.



Smeggy, I got the figure in exactly the same place as the 10% figure, so enough of the negativity already.



No.

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Before you moan about middle-lane hoggers, check that you yourself are obeying all the rules of the road.

I considered that but that would only relate to PICs, which are not nearly related to KSIs (which is close to FSAs), KSI being the characteristic used to describe camera effectiveness and RTTM .


So motorists tend not to read signs when on motorways – especially new, bright yellow ones?


This is true - if you are prepared to discount all those drivers who can see the 'appeal for witness' signs - but ultimately redundant. See below.


It’s more significant than you give it credit for. See below


Good, that’s what I thought.


Not really, it’s very simple: it means that something hasn’t been considered correctly, or presented in a misleading way.


The figures given are entirely for urban areas. The SCPs didn’t submit data for the fast roads (I’ll return to this at the end).







Let than sink in for a bit.





Recall how I was talking about ‘bias on selection’ with regard to ‘a pedestrian barrier/crossing, central reservation, junction re-layout, etc’ and your response was ‘Except that I’ve told you that the A3 is a three-laned road. There aren’t any extra traffic calming features.’ – well your response didn’t actually apply and I was completely correct.

Now, do you agree that the effect of ‘bias on selection’ can be very significant and is likely be quite significant in these urban areas? Don’t forget, we’re talking about urban roads, not rural, fast dual carriageways or motorways, areas where there are likely to be newly installed safety measures within the defined camera site length, measures such as pedestrian barriers/crossings, central reservations, junction re-layouts, etc, as well as the 'appeal for witness' signs.


BTW:

So roads like the A3 are more prone to RTTM than we thought. What a pity the damning figures were not made available – very convenient too don’t you think?

Maybe it's just me but I don't recall seeing any accident signs on fast roads. And I've only very rarely seen them on urban roads; whereas I have noticed flowers tied to lamp posts much more often.



As I said above, the number of 'appeal for witness' signs I've seen on fast roads is very few. And I do drive regularly.



Yes, maybe it was wrong of them to average out the different types of speed camera. So the figures we should use are 9% for mobile and 17% for fixed, but should deliberately avoid the 10% average figure.



I thought that you were on to something for a moment here with the central reservation point, but then I remembered that the A3 and other such roads have had central reservations for a long time.



Er, no, I must have missed it but I don't see what you are relying on here, especially given my above point.



Again, I don't see what you are suddenly on to. Yes, within the defined area which the camera applies to there may well have been extra things installed, but I just don't see why they should necessarily be (that's not to say that they're not) responsible for more than a very small percentage, like 1%.



No, not really, because they say that it is an "initial analysis" - give them time.

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Before you moan about middle-lane hoggers, check that you yourself are obeying all the rules of the road.

So what is included in the general downward trend and how is it calculated?



No because in the past I saw figures which showed that speed cameras cut KSIs. Those figures might well have been superseded but...

Even if it had just been a gut feeling, that gut feeling has clearly been backed up in my view by these stats.



What, by apparently ignoring 'bias on selection', something which could be responsible for only a very small reduction?



If I still haven't answered this question, what was it?



No I disagree. I think that if you are genuinely looking out for hazards then you will have no problem in spotting yellow speed cameras.

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Before you moan about middle-lane hoggers, check that you yourself are obeying all the rules of the road.

Why are you so convinced of this, given that speeds in excess of the speed limit have been shown to be the cause of less than 5% of KSIs? How would a device that only affects one factor, be able to effect an improvement with magnitude greater than that of the factor itself?

It could of course mean that the roads you frequent haven’t suffered from a serious accident. I’ve seen quite a few of these signs. Then again it could indeed just be you. I’ll come back to this.


Averaging out has nothing to do with it.
My point was that Monbiot didn’t point out that the figures were in relation to urban sites only, but then he didn’t point out the long-term trend within the figures either; well what did we expect from him!


That’s completely irrelevant in this case.


Our prior discussion on ‘bias on selection’ was based on a particularly fast road where little can be applied in the way of additional safety treatment. The figures are actually applicable to town/city roads where many safety tools are usually deployed, these being greatly effective (like pedestrian barriers which stop people from running out into a road, or crossings which separate pedestrians from traffic, or cycle lanes which separate cyclists from traffic, that kind of thing), many within reach of a camera site (the reach of which can be many km). The level of these external influences can be highly significant, you certainly cannot rule out that possibility. Don’t forget, the SCPs have been very naughty with their numbers, so who is to say they haven’t deliberately engineered the ‘reach’ [length] of their camera sites to sneakily include these other safety measures? (the SCPs can tailor the length of each camera site as they please). Besides, where would these additional measures tend to be placed: at accident sites or literally miles away from them?


The report was published two full years ago! The surveys were completed in 2003/4! There has been nothing since. Just how much more time do they need?


What logic can you apply to justify that claim?

Real hazards are in the road or have a potential to be in the road. Speed cameras are neither. As of April 07 they don’t even have to be yellow. Many are hidden behind signs and foliage. Many mobile sites are just plain hidden, these form the bulk of urban camera sites (as per the report).


The national trend. Read the report for yourself. Judging from the numbers quoted in your posts you would appear to have a copy. Do you agree that the effects of ‘bias on selection’ are not accounted for?


Err no. I have already demonstrated to you the RTTM effect; on top of that I demonstrated how the analysis and conclusion of the stats are flawed. For you to come out with a comment like that no shows you haven’t understood the argument put forward to you.

Your ‘gut feeling’ was subjected to RTTM (and long term trend, and ‘bias on selection’); how it can differentiate such small differences, for such infrequent events, is beyond me. Furthermore, if you know of these events then you have just shown that drivers can indeed be aware of when and where accidents occurred – even on roads like the A3.


That could be, but quite unlikely given the fact the figures are for an urban setting and the size of camera sites. Bias on selection could even be responsible for much more reduction than the perceived effectiveness of a camera site (the camera actually having a negative benefit).


You have since answered it, but not properly or in the context of urban areas. Care to try again?

Given that the best study on the subject has shown that 10% (absolute) of the KSI fall is due to speed cameras, but that ‘bias on selection’ exists and was unaccounted for and that it could be very significant in these urban areas, do you agree that the 10% figure is likely to be significantly optimistic and that the actual figure could actually be 0%, or even negative? If not then why not?

No they certainly have suffered from serious collisions. From the occasion when I've looked at the local papers, plus you've got all these speed cameras.



No it wasn't, you were saying how did they get to 10% when there were figures of 9% and 17%.



Hold on a moment. How do you know that he wasn't using the 19% figure in table H8?



Hmm, if you say so.



Presumably then, if it is the case that after installing fixed speed cameras there was a reduction in FSCs (on the A3), then you would support the idea that it was the cameras that were responsible?



Yes, but how many of these things have been in place for many years? For example, pedestrian barriers haven't suddenly sprung up in recent years have they?



No I thought it was one km.



Really?



But see above. Many of these things have been in place for many years.



Smeggy, these statisticians aren't going to have unlimited time, and by the looks of things they do do a lot of work. Give them another couple of years.



Er, well, a hazard might be someone standing at the side of the road wearing dark clothes. At least, you should treat them potentially as a hazard because they might try and suddenly cross. If you are looking for them then at the same time you will see speed cameras. It's obvious really. If you can't spot speed cameras, at least the yellow ones (of which all the ones in my area still are), then you are not paying enough attention! I have absolutely no sympathy with someone caught by a yellow speed camera.



Like people.



Many? Really? (I think this is a good thing as you shouldn't be breaking the speed limit anyway, but that's a separate argument.)



On what page does it say that they are hidden?



I will take your word for it.



Well, you have pointed out the figures.



What, you mean 'bias on selection' which could well count for almost no effect? Or do you mean something else?



Well let's go through this again then:

1. 55% total reduction, yes?
2. 35% of that down to RTM?
3. 9% down to trend?
4. Which leaves about 10% down to the cameras, does it not?

Isn't the only thing remaining here 'bias on selection', which may or may not make up that remaining 10%? (You think it does, I think it doesn't.)



That's because I some times read the local papers, and because it's important to me so I tend to take note. But how long is it going to stay in someone's mind? And people know that things are bad but they still do them. As for the A3, actually I couldn't tell you where exactly collisions had occured.



But as I've already said, in these urban settings you already get a lot of barriers and things like that even before speed cameras are installed.



"Not properly"! Oh yeah, as if you're a fair judge of that!



I doubt you will accept this as a proper answer but anyway.

From before: "Sure it could be 0%." I accept that the 10% figure "must" be optimistic, but only in a technical sense, which is to say that 'bias on selection' may make a marginal difference. I don't agree that the 10% figure is likely to be significantly optimistic because many of the 'bias on selection' things you mention have been in place for many years. As for the ones that haven't been, we simply don't know what difference they make. "Also, it's interesting and worth noting that whilst (urban) mobile speed cameras are attributed with a 9% drop in FSCs, fixed cameras were attributed with a 17% drop."


Now Smeggy, this is a nice long post so try to make it last you a few days...

_________________
Before you moan about middle-lane hoggers, check that you yourself are obeying all the rules of the road.

Not meaning anything untoward .. but you remind me of someone posting likewise on a cycling rant forum.


Let me be plain. I ride a bike .. Enjoy this. I think it keeps me able to satisfy the demands of my wife.

But daft comment aside.. I admit to a feel good feel after a crispy ride. :


But the comments as seen ..on a certain cyclist only forum. they do beggar all reasoned belief.

Be assured .. a chap awaiting major heart surgery imminently would not b helped by cycling and he did the right thing by going for a short walk.


But the guy was committed. to a cause. Sometimes this becomes a reason for living.

No disrespect to a nice caring chap. Quite the opposite..but I can guess and understand all the same as a human being who just looks a little more intensely at a human dilemma.



As the C+ so called lawyer once said to my in-laws.. "it'sa forum".. so they got ex editor to format a decent forum.. and the non-cyclists flocked to some other place to post invective without substance. ]I do not think I've been rude and do apologise if you think my wife, me or for IG have been so. We tease.. banter .. but do not seek to actually offend here.

But C+ conceded the insults and took action.. and I suppose you could accuse the Swiss of closing C+ as it was.. but giving birth to a decent medium which focuse on the serious matters of cycling in the real world as well as the sport.


We are not .. and never have been .. an "enemy" of another road user however they choose to travel. That's something dreamed up by a poster called spindrift whose posting and surfing frequency tell the average idiot.. let alone the educated astute// that no job is held .. and that no cycling to place of work exists/.




Apolgies but you come across as deja vu...



OK ... so you may not be who I suspect here


We've had trolls galore here. already My wife and in-laws have troll dollls and I do wonder at my wife when I saw the evidence of a "marriage with Barbie and a Scandinavian troll and scalextric


But mate.. it's Christmas .. and I must change into a suit Have a snack..
go to Mass .. light a candle for all I know personally and "virtually" - and pray for all my pals .. especially Paul Smith whom I liked very much.


I then return to exchanging gifts and fry up in olive oil. Traditionally I say grace again and I wil be wishing all the best to all debaters on this site . whatever their take and a very special personal thought for Claire and Paul/

So all the best .. our friendly "fiend" here and I will chat with you again after spending precious time with my kids.

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A few things occur to me here, firstly the figure attributed to RTTM. Was there any quantitative study that apportioned the 35% figure, or is it just an educated guess, as it seems?

The 'reach' of camera sites is 1.5km for GATSOs, 3km for mobile cameras and 10km for digital enforcement sites, per the guidelines.

One would have thought that with the massive sums of money being generated by automated speed enforcement, they could afford to take on a couple of extra statisticians to publish the result within a reasonable timescale. Unless, of course, they do not want the result to come to light.

Given that speeds in excess of the speed limit have been shown to be the cause of less than 5% of KSIs, how could a 10% reduction not be considered optimistic? How would a device that only affects one factor, be able to effect an improvement with magnitude greater than that of the factor itself?

Edited to ensure thread stays on-topic by removing temptation.

Your claim would suggest your council does not deploy these ‘appeal for witness’ signs; that would be unusual, as well as perhaps unwise.


Yes, it was. You’ve got yourself confused. My referring to those figures was to point out that it could not possibly have been for all roads, I used the ‘averaging out’ to prove it. Look back through the thread, now do you understand?



H7 is referring to the before/after change of fatalities at camera sites.
H8 is referring to the ‘real’ change (discounting ‘bias on selection’ [I will refer to as BoS from now on]) after a scheme relative to the expected change after non-implementation of a scheme – an after/after characteristic.

The well-known phrasing ‘there was a XX drop of KSI at camera sites ’ is a before/after characteristic; hence use of H8 is invalid in this context.

H7 it is!


Do these mean you don’t have a counter for these and that you accept what I claim? If not then please state why?


Nope. RTM will account for more than what the previous figures suggested (how much more we don’t know, it could be the rest of it), long-term trend will be the same factor, leaving even less for the perceived effectiveness (not accounting for BoS).


You thought wrong. The previous cost recovery rules stipulated that fixed sites are up to 1.5km, mobiles up to 5km.


Yes, RTTM. They’re still relying upon that illusory benefit even today.


link
No mention of the possibility of RTTM, long-term trends or even BoS; now that’s naughty huh? There are many more examples in current use, I won’t bore you with many links.


That’s the funniest response I’ve read in this thread.

It took 1 year to collate the data, analyse it, put that into a study, then compile and publish a report partly based on that study. Three years later and still no whiff of a study (let alone a report) based on the rural data, even though an initial analysis had already been done in time – and you think they need yet more time?

Let’s allow the reader make up their own mind with that one!


That was a non-sequitur, not application of logic.
Someone standing at the side of the road can step into the road; a camera cannot – everyone knows this. Yes such a camera will be in the field of view, but as I said before, it will be subconsciously discarded. I don’t think you need to understand how the human visual process works to know that your conscious thought process does not concentrate of all items in the field of your view, the unimportant items are instead subconsciously filtered out. When you are typing are you constantly aware of all the static items on your desk, floor and walls?


Yup: http://www.speedcam.co.uk/gatso.htm
I don’t agree with all of the sentiments written on that page, but this is enough to give you an idea of what I mean: hidden and not yellow – and those are just the fixed sites!
(I might add that I’ve never been caught, not once in my entire 10 years of owning my full UK license).


It is illogical to suggest your gut feeling can be supported by an analysis that is flawed (unaccounted BoS). You have accepted that BoS can be significant "Sure it could be 0%."; therefore you cannot make your firm claim based on the figures.


Yet you are happy to take my word for things?

To address this issue: you didn’t acknowledge, let alone answer, the part of my question that asked ‘or even negative’ - and you again didn’t. Care to try again? I would like an answer to that.


Of course not all of them, but many have. Some will have been installed in response to the accident cluster that justified the camera sites:

merthyr.gov.uk: "Safety cameras complement other measures to improve road safety... "

flintshire.gov.uk: "use of Interactive signs to complement existing speed cameras on Arrive Alive routes"

safetycamera.org.uk: "Using a combination of education, engineering and enforcement the Partnership has significantly reduced the numbers of casualties at their camera sites. "

sussexsafetycameras.gov.uk: "They will work as a complement to the speed cameras ... "

merton.gov.uk: "You may be aware that speed cameras have already been introduced in Church Road and it is considered that the proposed measures will complement the cameras and those measures previously introduced. "

I genuinely could go on and on but I’m sure you’ve already got the gist of it.
As you can plainly see, the practice of mixing other safety features into camera sites isn’t what anyone would consider to be uncommon.
(Note that I quoted only from UK SCP/government sites)



So what difference do you think measures like the following make?
- pedestrian barriers which stop people from running out into a road
- pedestrian crossings which separate pedestrians from traffic
- or cycle lanes which separate cyclists from traffic
Go on, have a stab at them.


That’s because fewer KSIs are needed to justify a mobile site. Less rise results with less fall, hence the difference.



Merry Christmas

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Views expressed are personal opinions and are not necessarily shared by the Safe Speed campaign

Everyone,

this has been split off from another topic. Please feel free to respond accordingly in this thread.

We have just the one fixed PC Gatso here and we move him around

His location is always

Whether or not he has a camera inside his head .. no one's actually sure

Is he at revenue spots? He's not there for revenue purposes - just to warn we are around somewhere

We have one cam van doing the rounds - on roads which we know have a history of .. er "silly-ish" behaviour. We do advertise in advance though .. and we have little "Slow Down/Kill Your Speed/Think!" signs along these roads.. and we don't really cop that many as a result. So .. is it the threat of the van team or the reminding signs


Engineering.. signs ... Cat & Fiddle became a lot tamer within weeks per Cheshire - and they have one car patrolling the rounds up to the border with the High Peak as well.

So basically - we cannot say cams are effective when other measures have kicked in to reduce the "dangers".

Said before - we have one dodgy area - headache with the bikers .. but again we have some on-going road engineering which seems to be taking away some of the "anticipated thrills and dissipating the red mist".


Have these roads "regressed to a mean?" Perhaps. But perhaps because for some roads out there - a number of factors - none of which can be taken in complete isolation just made them that less accident prone

Here? Lot of police actually seen to be doing a job. It does make that difference.


I would not recommend committing a traffic or any other offence here

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Er, but I and this report never said it was for all roads, so why do you say that? It is only for these areas where speed cameras are in place, and only the ones which they did the research on for the report.

And it's not "a large weighting of 17% summed with a smaller weighting of 9%" - for this report it's actually the other way round.

Anyway, I am now bored of this whole argument, so if the above response (or any other response in this post) doesn't make sense then just assume that I don't understand and tell me.



I shall take your word on that for now.



Smeggy...! Well if you expect me to reply to every word you say then I will do the same back.

"Hmm, if you say so."
Alright, please explain exactly what you meant by this: "well your response didn’t actually apply and I was completely correct."

"I will take your word for it."
I really can't be bothered to read the report. Me saying that "I will take your word for it" obviously means that I don't have a counter and am happy to accept what you claim. I didn't think you needed it spelled out like that.



No in my question I was already assuming that that would be greater RTM. If all things are equal then there would be less left over for the perceived effectiveness, but then BoS would be less. Basically, I want to know if you would ever say that speed cameras are having an effect.

Also, I have now thought of an additional factor which hasn't been taken into consideration before - the police's actions once a speed camera has been installed. Before a speed camera is installed, I imagine the local police would build up a knowledge (over the space of many years) of what a road is like. If a road is known to be more dangerous presumably they would watch it more. However, once a speed camera has gone in, the police would divert their limited resources elsewhere. With this in mind, the actual effectiveness of cameras could in fact be more than the official figures.



Which just shows an even bigger difference between fixed and mobile cameras. I'm pretty sure I asked a short question relating to this.



I completely agree that the above is wrong.



Just for my future reference, why exactly do you say that?



I simply disagree that it will be subconsciously discarded. There will be other static items such as static cars to look out for. And road signs, for example Give Way and mini-roundabout signs. If you are going at a speed where you can look out for and react to many different types of hazard, then I believe in the process you will have no problem in spotting speed cameras.

Can we now just agree to disagree on this?



Well fair enough, but I would like to say that all the speed cameras in Greater London and Surrey, where I drive, are completely and easily visible.



You didn't reply to the above.



Smeggy, you didn't directly reply to the above and considering that you said my comment showed that I hadn't understood the argument, I think it is only fair that you reply.



This gut feeling business has become a bit of a strawman. Of course my gut feelings can't take account of various different things. Also, nowhere have I accepted (otherwise please point it out) that BoS can be significant. What I have been saying is a technical point: "Sure it could be 0%". I don't reckon that it is though. (*sigh* I did make the mistake of not putting the word "could" in bold before.)



They are different things. I shall take your word for broadly what it says in the report, but I won't (always) accept your judgement.



Sure it could be negative. Do you accept that, with the (unknown) actions of the police, the figure could be higher than the 17% given for fixed speed cameras?



Alright, the first makes a 1.3% difference, the second a 0.4% difference and the last a 0.1% difference - happy?



I'm not sure that that makes sense when you take into account, as we have done, RTM.



Happy New Year.

I know you didn’t, but earlier in the thread you seemingly didn’t know it wasn’t. I’m highlighting this because Monbiot’s take on it lets the reader assume the figures he gave applies to all roads, this error being in favour of the perception of speed camera effectiveness.


I know that, that’s what I had highlighted at the bottom of a previous post here, so demonstrating what I had said just above. Please keep up.
As bored as you might be with this, my point is that it is further incompetence or deception by Monbiot: "The fresh figures showed an average reduction of 19% for collisions that caused deaths or injuries after speed cameras had been installed." – now does that seem like it was correctly conveyed for urban roads, or does it lead the reader to assume it applies to both urban and rural, the latter being where the RTTM effect has so far been shown to be greater?


"For now"? Are you planning to return to this?


Your opinion was based on the misleading Monbiot article which leads the reader to assume all roads; your subsequent argument included a non-urban road (A3); we’ve since discovered the figures are for urban roads only; hence your analysis of BoS on the matter (using the A3 as the example) wasn’t really that relevant.


I’m not sure you’ve realised this but the RTTM effect can be masking an actual negative effect of the camera.
We know the RTTM effect is greater on rural roads, it’s just that we have no indication of how much greater, but it could be a whole lot greater.
Say for a Baseline drop = 55%:
- Trend = 10%
- RTTM = 50%
- BoS = 0%
so genuine camera effectiveness = -5%

So to answer your question, they’ll be having some sort of effect, but we don’t know if it is positive or negative.


You were also pretty sure the figure was 1km; you were wrong – yes?
My original point being: it is significantly likely that other added safety measures are within the defined reach of a speed camera site. Do you agree?


Good! Would you accept that given Safespeed’s significant media coverage highlighting these flaws and the combined resource of >40 partnerships, each with their own analysis and PR department, their continued used of these flaws can only mean that they are deliberately being deceptive?


The argument doesn’t follow because there is no logical connect. You made the assumption that all objects within the field of view will be consciously noted and acted upon; this known to be incorrect. Also, you assume all speed cameras will be roughly in view where people are waiting to cross the road; this is also incorrect.


Why do you disagree that they will be discarded? You can’t just say it will be without some sort of supporting argument. I’ve given mine.

Cars are in the road and have the ability to pull into the path of a moving vehicle, cameras don’t and can’t.

Signs also have symbols that are used to communicate information. This is of course more effective than just a simple coloured background which communicates nothing. Not forgetting that some are hidden....


How do you know you’ve noticed all the cameras – especially the mobile ones?
Will all sights around the country be as conspicuous as those you’ve seen? (such as those in Greater London)


1, 2 and 3 are correct. 4 is flawed because it makes no provision for BoS (regardless of how insignificant one believes it is).


You’re all over the place. You accepted that the effectiveness of speed cameras (accounting for trend, RTTM) can possibly be entirely down to the effect of BoS (and that BoS can be even greater), yet you say that you have never accepted that BoS can be significant ?!?


This is a good point: reverse BoS, cameras displacing (or even replacing) trafpol.
To answer your question: yes, although I think the many other forms of positive BoS would completely swamp that particular effect (see below).
Also, trafpol will still have to look out for the plethora of other poor or anti-social driving which speed cameras simply cannot detect. We know that the great majority of crashes happen with all those involved within the speed limit, so why should trafpol not need to police at camera locations? (apart from not wanting to risk getting caught themselves).
Hence I don’t think your argument, while valid, is significant.


In that case, would you mind commenting on my argument of “the practice of mixing other safety features into camera sites isn’t what anyone would consider to be uncommon.
(Note that I quoted only from UK SCP/government sites)” and the links I used to support it.

Would you agree that urban camera sites are often mixed in with other safety measures?


There is no need, see below.


I have a confession to make. When I was searching for the links showing the instances of deliberate BoS, I found an old TRL document with a table stating the effectiveness of those other measures. I wanted to gauge your ‘gut feeling’ on those before I told you of those results:
- pedestrian barriers (urban) = 46%
- pedestrian crossings (urban) = 36%
- cycle lanes (cycle schemes, combined) = 58%
Table 7: Treatment types by Location www.trl.co.uk/molasses/Web%20tables.doc There are plenty of other measures described within.

I should point out that the report accepts there could be a significant level of BoS (now why don’t they ever admit that for speed camera sites?), but this would likely be less significant than that at camera sites because the definition of the reach of these other measures would likely be less than camera sites, certainly less than 5km anyway.
The level of RTTM is very unlikely to be as significant because the policies allowing the installation of these measures are not based solely on recent prior history (if at all).
I estimate that long-term trend would account for 20% of the fall (1994 to 2000 was from a time where the rate of the fatality drop was better).

Would you not agree that the effectiveness of other measures can be very significant?


I see what you mean, it doesn’t does it. I can’t explain why the RTTM effect is greater at mobile sites. It does seem to go against what is expected, but I have no reason to dispute the outcome of the RTTM study (or that of long-term trend).

The difference could be that fixed sites suffer from greater BoS due to the nature of the rules allowing them, unfortunately there is currently no way for us to know.

I'm not sure you did. You were accusing me of being selective with my figures, in other words you didn't believe the 17% figure.



Like others on here, you seem very keen to get someone else to admit that they were wrong but aren't willing to do so yourself - I shall give an example of this. As for the figure being 1km, I must have heard that it was one mile, not one km, but yes, I am quite happy to admit that I was wrong to say one km. But I say again, I am pretty sure that I asked a short question relating to the above...



Yes but we don't actually know what effect they would have.



You really do like to go on don't you? Yes, for now, I shall agree with the above.



Because drivers know that there are various motoring laws which are enforced by different means.



Why do you say "of course"? A yellow surface on a box communicates something to me.



Because I am observant. Of course I can't say for absolute sure that I've noticed them all, but I believe I have.



Ultimately, this argument doesn't mean anything to me because I believe in the speed limit. If speed cameras are hidden then so be it. But if I was driving in an unknown area then I would be driving that bit slower.



But Smeggy, I then had this bit: "Isn't the only thing remaining here 'bias on selection', which may or may not make up that remaining 10%? (You think it does, I think it doesn't.)"

You replied to that in a rather illogical way if I may say so, but you ignored the previous points, which is why I copied them down. Now taking them together... are you willing to say that I HAD understood the argument?



I'm not all over the place at all. This is just you, Smeggy, not paying attention when I use the word "could" or say a technical point. I shall obviously have to somehow be clearer for you in future.

We don't know what numerical effect BoS has on the numbers, right? Therefore, research could show that it is highly significant, or it could show that it is not significant at all. In your opinion, it is highly significant. In my opinion, it is not significant. And when we take into account another unknown here, the police's actions once a speed camera has been installed, it could be that cameras are actually more effective than the numbers show.



No, you were already doing that.



I agree.



No because you don't accept old TRL documents in other cases so I don't see why you should start now. Unless you are cherrypicking of course.



Right, I think it is more than time that we end this argument, so it would be good if you could summarise your position on this subject.

Could you both summarise your positions? Or have you dug so far down into the weeds you don't actually know what you are arguing about

I thought I was reasonably intelligent until I started reading this

Sorry Jeff, but I believe there is more unexplored discussion to be had out of this.


What are you on? Your being selective with your figures (urban only, not rural too – be it not intentionally) does not mean I don’t believe the 17% figure.


Yet that’s what I did at the end of my last post. Ho hum!


Which was? I’m sorry if I missed it, I don’t think I had missed anything of relevance.


You are guilty as I of ‘going on’.
"For now"? Are you planning to return to this?

Given that you’ve agreed that the SCPs are being deliberately deceptive, coupled with their financial gains from it, do you agree that the SCPs are committing fraud, as well as deliberately encouraging misallocation of road safety resource?


How on earth does that justify your stance of speed camera boxes not being subconsciously discarded in the mental safe driving process?


To you perhaps, but you can’t assume it consciously communicates something to everyone; it doesn’t to me. Like I said, unlike cars and pedestrians, they’re not and can never be a direct road hazard.

Would you disagree that one is more likely to notice a yellow square surface with a command/warning symbol on it compared to one with no distinguishing mark? If so then please explain why.


Even the ones you’ve just indirectly agreed are hidden? I will let the vehicle driving reader be the judge of whether you’ve likely spotted all the fixed and mobile cameras whilst driving. IMO if you are observant enough to notice all speed cameras, especially the hidden ones, then you’re very easily distracted.
My overall point being: those genuinely looking out for hazards can have problems spotting yellow speed cameras, especially those hidden.


Seems to me like you’re ducking out of the argument.


I don’t doubt that you now understand it, but your earlier comment of "Even if it had just been a gut feeling, that gut feeling has clearly been backed up in my view by these stats. " strongly suggested to me (and still does) that you didn’t so I wanted to make sure. My apologies if you actually did understand it at the time. We can leave this one here.


That’s all I wanted you to understand.


I’ve given my reasoning as to why I believe this effect is insignificant. Do you agree with my reasoning?


That’s the funniest fallacy of this thread. You don’t agree that other measures can be very significant because I didn’t accept some old documents - what kind of reasoning is that?
Also, what other ‘TRL documents in other cases’ did I not accept and why should that lead me to disbelieve this one?


Oh no you don’t! I want to know how you believe the other measures mentioned to be insignificant, so please do explain.

Okey dokey.

_________________
Political Correctness is a doctrine, fostered by a delusional, illogical, liberal minority and rabidly promoted by an unscrupulous mainstream media, which holds forth the proposition that it is entirely possible to pick up a turd by the clean end.

In what way am I being unintentionally selective? You've got yourself confused here - you were accusing me of being selective... You said "Where did the 17% figure come from?" The fact that you later accepted the 17% figure as fact doesn't mean that I couldn't reply to a different previous sentence of yours, showing that I knew that this report didn't apply to all roads.

Anyway, perhaps we can drop this now?



Hmm, not quite in the words "I was wrong" or something like it though.



I shall come back to it at another point.



No I'm not because you've now added yet another point below!



Perhaps, perhaps not.



Whatever happened in the past, I thought that they didn't make financial gains any more?



Alright, let's change that. I disagree that they will be discarded because the driver has to look out for other things, such as road signs. Yellow speed cameras are just as obvious as road signs.



What, not "this is likely to be a speed camera and you will get in trouble if you break the speed limit whilst going past it"?



But you've changed your argument a bit here. You were saying that people wouldn't notice them because they are static. Well road signs are static as well and people notice those.



No I wouldn't disagree.



Eh? I drive a car myself you know!





You see, you do want to just keep going on don't you! I'm not ducking out of the argument - I've given my points above.



And do you understand that research could show that it is not significant at all?



At least a speed camera helps to cut down on one cause of crashes. Although I agree that there is a "plethora of other poor or anti-social driving which speed cameras simply cannot detect", with their very limited resources I reckon that trafpol would decide to concentrate on other areas all the same. So I don't agree that it is likely to be insignificant.



If you don't accept old TRL documents as being true in some case, then how come you accept that they are true in this case? I think that you either wholly accept what TRL say or you don't, but you can't cherrypick points to suit your cause.



Firstly, banning SteveCharlton seemed to me to be a way of shutting up someone with very good points. I'm not going to start quoting them but there are loads of good points in this post of his: Mon Dec 31, 2007 3:23pm

Do you accept everything that he said in that post regarding TRL? If you do then perhaps I can accept that you are in fact being fair regarding your use of their statistics now.

In direct response to your question, yes, it would appear that the effectiveness of other measures can be very significant, but that doesn't mean that they are when in the same location as speed cameras. How often are these things put in where speed cameras are? We simply don't know.

My overall point is that you can't claim that BoS is significant without having some direct research to fall back on.



Let's argue and argue for ever, says Smeggy.



Dealt with, I think.

Jeez, talk about trying to divert the topic. This is so stupid it deserves a separate post:


Don’t you think it is extremely disingenuous to say that I’m cherry picking, then you cannot prove it when asked to confirm, then try to engineer a situation where you get me to cherry pick?
Cue the readers laughing at you!

Do you agree that, contrary to your claim (highlighted above for your convenience), I didn’t ‘not accept old TRL documents in other cases’?

Even if I did, to say that I must disagree with all research from a group (let alone particular contributors) because I disagreed with just one of the reports is just plain silly.
Do you now reject everything the government and camera partnerships have ever stated because they didn’t (and many still don’t) correctly report the effectiveness of speed cameras (which you have already agreed) ?


How did that answer my question?
He might have had very good points, but he was banned for repeated unacceptable behaviour despite unequivocal warnings. His points were countered in the other thread. If you wish to discuss those then please do so in that thread. Please note: I didn’t dispute the documents.


I have not looked into the other TRL documents, I’m not going to look into every TRL document and say ‘I agree/disagree’ just to make you happy that I’ll accept this one. You don’t think to do so would be just a little bit ridiculous?


Now, I could put the shoe on the other foot and ask you if you accept the figures given in the TRL report I gave. If you reject it then I could try to get you to reject all the other TRL reports on that basis, but I don’t want to needlessly muddy the arguments.

I take each argument/input on its merit, as should any sincere debater!

Stop this silliness and return to the debate.