I wonder if a maths A level
will be required before allowing those idiots that don't know how to accept responsibility for their own actions use this a weapon in court to get them removed.
The Department for Transport is proposing that councils and police will have to publish data about speed cameras. The data could include accident rates at speed camera sites, vehicle speeds and the numbers of drivers prosecuted or offered training after offences are recorded on camera. Road safety minister Mike Penning said …
will be required before allowing those idiots that don't know how to accept responsibility for their own actions use this a weapon in court to get them removed.
When I did maths A level (pure and applied) there was very little by way of statistics in there. I also did statistics O level which obviously was more relevant and was actually at a higher level then the little bit of statistics covered in the A levels.
Analyzing statistics, however, isn't just about crunching the numbers it's also about understanding what the statistics can actually tell you. Those safety partnerships that already publish the statistics have already had loads of hassle from idiots who just don't understand what the statistics can tell them. One of the most important things about any statistical data is knowing how the figures are recorded and what they actually record. For example, how many people know what constitutes a "serious injury" in road accident statistics? In most cases being taken to hospital will be recorded as a serious injury. So a mild case of whiplash may be recorded as a serious injury.
Somebody somewhere will of course mention regression to the mean (RTM) which is a favourite phrase used to explain away any inconvenient data that seems to show a speed camera is doing it's supposed job. The problem is that some people don't actually know what RTM means they have just heard it somewhere and trot it out to support their argument.
Some speed cameras do the intended job because they were placed sensibly by the local "safety partnership" - for example on roads with poor forward visibility particularly near junctions. Others are less effective because a particular safety partneship got the funding for a certain number of cameras on a particular road and just banged them in any old where.
I don't know when you did your A-level maths, but the AQA A level that my son is currently taking is about a third statistics. The remainder is pure maths and mechanics.
"For example, how many people know what constitutes a "serious injury" in road accident statistics?"
I've no idea, but where is your evidence for your bald statement: "a mild case of whiplash may be recorded as a serious injury".
It's all very well critisizing the use of statistics, but if your are going to make your own claims, they would be more compelling if you backed them up.
The very first sentence of the definition used for these stats starts - An injury for which a person is detained in hospital as an “in-patient”. If you are taken to a hospital as a result of an RTC then it is a serious injury, even if it turns out there was nothing wrong after all. I fell victim to this when I hit an object in the road one evening when coming home from work on my bike. At no point in the ensuing slide/tumble did I hit my head, nor was the initial impact substantial as it was a low angle sliding hit. I was up and about having checked myself and felt comfortable to remove my Helmet but the GP who attended before the ambulance arrived decided I should be immobilised on a backboard and taken to the Resusitation Room for spinal check and Neuro obs.
Net effect was my bike jacket and trousers were cut off me (gosh, couldn't recover the cost from the Insurance company) and I was held in hospital for over 4 hours before they decided I was fine and could go home without even needing painkillers.
Helmet was in perfect condition, laptop in my backpack was in perfect condition but I was listed as a 'Serious Injury RTC'
"Somebody somewhere will of course mention regression to the mean (RTM) which is a favourite phrase used to explain away any inconvenient data that seems to show a speed camera is doing it's supposed job. The problem is that some people don't actually know what RTM means they have just heard it somewhere and trot it out to support their argument."
..... You just used RTM to support your point without explaining what it means. Are you any different from others? RTM is real, its effects must be allowed for, deal with it.
It was JMB a level maths, pure and applied papers.
My evidence. I had an accident a few years back that got me sent to hospital where the doctors decided to keep me in overnight "for observation". Basically this "observation" involved going to bed and not seeing another medical professional until after breakfast. This bloke gave me a very cursory examination and sent me home telling me I had a mild case of whiplash and should rest for a week. This was enough to class me as seriously injured.
An awful lot of people are kept in overnight after a road traffic incident to make sure they're not going to suddenly show signs of serious injury. Ever heard of the so called "walk away and die syndrome"?
RTM isn't the problem, the problem is the way the statistics are created in the first place. If the sample size is too small the data is meaningless. Which is pretty likely consdiering as far as I am aware 3 "serious" accidents in a year is sufficient to mandate a speed camera, which would mean even if 3 is your mean value and not an abberation icovered by RTM-type arguments t'll take you many years (not a statistician but hmmm what? 10 years maybe?) to determine what the mean value of accidents is.
Then you need a similar value counted in the same way (which it has been suggested is not the case with different sample areas before and after camera installation) with and without cameras - oh and it helps if the road conditions remain the same though the sample periods (doesn't sound too likely if you're talking about 20 years - in the last 20 for example ABS was invented and became more common).
That to me suggests that there's no way any statistics released produced since the widespread use of speed cameras are likely to be shakey at best and totally manufactured to corform to expected values at worst.
A more sensible approach would seem to be an overall analysis of accidents against spped camera use and statistical analysis of trends there. That's what these guys seem to have done:
You may not believe their conclusions about the links to speed cameras but they make a reasoned argument and support it with data of a decent sample size.
Or if this is to be an unbiased article, presumably you may also be able to disprove it?
...is that like traffic wardens, people loath speed cameras with a passion. While it's a positive thing that they are showing post capture prosecution/training statistics, the key thing people will look for to justify the use of speed cameras are whether it (significantly?) reduces accidents along a given stretch of road/given area.
I'm not sure how easily this data is available. But I imagine that Speed camera's that have been situ for a significant amount of time, it would be more difficult to find meaningful comparative statisitics when you bear in mind road surface improvements / other contributing factors.
"bear in mind road surface improvements"
I seem to remember some testing done that was reported on the Beeb that modern road surface is actually *less* good and more slippery in at least some conditions (something inevitably to do with cost as I recall) .
There's also the argument that accident statistics include *all* accidents on a stretch of road including perhaps the random guy that jumped off an overpass bridge or deliberately stepped into traffic.
Added to that in most sites the numbers are likely to be small for a given camera area and a "30% reduction" or even increase in accidents doesn't statistically mean much if you're talking about 3 accidents a year and not much more of you're talking about 20 (a reduction of 4 could easily be normal varience).
It's also worth saying since I am one of the people that loath(e) speed cameras that I've been driving a fair number of years and over the years have had a fair number of accidents some my fault others not. In not one of them was any party involved driving above the speed limit. In fact having polled people I know on this subject, of every accident involving those people (which amounts to more than 50 accidents) I wouldn't run out of the fingers of 1 hand counting the number in which any kind of speeding was involved which suggests to me that "speeding" (as opposed for example to "driving too fast for the conditions", which is a completely different thing with only a peripheral relationship to speed limits) is not a primary cause of accidents.
In every accident I've been involved in or know directly about the major factors are either errors in judgement usually caused by inatentiveness or lack of driving skill such as responding badly to an emerging situation e.g. a skid (and yes I include myself in this too).
I've yet to see anyone explain how speed cameras help what the evidence I can see suggests is the real problem and likewise I don't see how publishing some random (and probably misquoted, taken out of context by both sides, and doctored) statistics will improve things.
Yes a lot of people hate speed cameras. The problem is that most people aren't even sure why. I hate some speed cameras because of the way they were implemented.
One road near me had a sixty limit which was dropped to forty and then almost immediately speed cameras were also implemented. The reduced limit was not given time to work. Yes there were a lot of serious accidents on that road and there severity was heavilly influenced by trees - there are lots of dry stone walls and trees to hit if you leave the road. Statistics for that road may appear to show that the speed cameras work - the serious accident rate does seem to have dropped since the cameras went in - but the statistics don't show whether it's the cameras that have done the job or the rduced limit alone. No amount of statistical analysis will show which is responsible or whether it's a bit of both.
Many people don't differentiate between speed cameras like this and sensibly located cameras - they just hate all of them.
I have no problem with speed cameras, providing they are sited correctly and in well thought out locations. Some places it makes perfect sense and some people have no idea where ease off the peddle a little, so someone else has to think for them. I would say that 90% of the cameras I have seen seem to be in an appropriate location.
I have seen places where cameras have been removed as they no longer make sense, they have done the job or the road has been adjusted allow faster speeds. It's good that someone goes back to check if they're still needed.
I look forward to seeing some of these stats, so see if the boast about saving lives does actually tally.
Does a successful speed camera raise loads of money or very little?
The speed camera that has nearly completely halted speeding within its view might be said to be very successful indeed, achieving the stated goal of reducing speeds to the legal limit.
And taking it away might obviate that success in days.
Claiming that xxx accidents have now been reduced to yyy due to plonking said speed cam is not always the whole truth, quite often road engineering is the main reason to reduction of accidents (such as roundabouts, better line of sight for hazards etc...)
If the accident information was also supplied with information of work done to the roads or surrounding roads (after all traffic may have been diverted) then we would be able to make a more informed judgement on value for money.
To use an easily seen example, look at the A34 on the run into Stoke-on-Trent, at the time I used it regularly, it had 24 cammeras (11 one way, 13 the other). Mostly 50 mph dual carridge.
Yes the road is dangerous,
Because you can do right hand turns (across 2 lanes of traffic) out of small country lanes, rather than being forced into a left hand turn down to the nearest roundabout (lots of them on that 12 miles of road).
Speed Cammera = revenue; life saving simple road alteration = cost.
Do the maths to find the driving force here.
Personally I always used the roundabouts, it was worth the extra half mile of fuel.
One one strech of road I know, they claim speed cameras have cut accidents by 90%.
So the reducing of speed limits, changing a dual carriage way into a single carriageway at certain points, closing central reservation crossing points, adding two new sets of lights, making 2 side roads oneway only and lengthing slip roads have had 0 effect then?
Lie, damn lies & statistics.
Just like the A50 as well...I'm sure there are more speed cameras in that area than there are people.
Heading towards Stone, there is one camera which is sited around 400 yards from another on the same carriageway, but just over the brow of a hill with no road joining from the left.
That was sited there purely to raise revenue and has nothing to do with safety. Fortunately, as I was a frequent user of the road I knew it was there but many unfortunates do not.
These unfortunates of which you speak. These would be the ones who are speeding right? The ones who are breaking the law?
What makes them unfortunate? Because they got caught? Just like all those unfortunate burglars, benefit cheats, murderers etc who got caught?
If you don't want the points/fine, don't speed. It's not hard. If people find it hard, then are they fit to drive?
I agree - lies, damn lies and statistics.
Paris, because even she could spot the lies...
"Just like all those unfortunate burglars, benefit cheats, murderers etc who got caught?"
Nice to see that you totally buy in to the government line:
Speeding = Theft + fraud + murder
Good to know. That's such a perfect analogy and not at all a vastly overblown and utterly irrelevant comparison that I have trouble grasping the full beauty of it.
A few things the stats won't tell us;
1. How do cammeras prevent dangerous driving, tail gating, etc.?
2. How do cammeras make the road safe in the event of an accident?
3. How do the cammeras provide first aid in the event of an accident?
Remembering that cammeras have been used as an excuse to replace traffic officers.
Ditch the cammeras, put traffic officers back out on patrol in marked cars, and watch the standard of driving improve, and the number of accidents come down!
Speed cameras are about enforcing the speed limit on a certain stretch or point of a road, nothing more.
Asking how speed cameras prevent tailgating or providing first aid is like asking how your marked police patrol prevents the moon from flying into space.
In regards to point 2. Speed Cameras encourage you to drive slower. Crashes at a slower speed result in fewer injuries and deaths.
As for replacing Cameras with Traffic Wardens.... Who's going to pay for it? We've already had to put VAT up by 2.5% to avoid worse cuts than we're already seeing.
When we have the data we can make educated statements and reasoned arguments to support our view on whether a particular speed camera, or speed cameras in general, should or should not be in place.
I fully accept that the data may be less than useful in some circumstances (particularly with no prior reference points) however it should be possible to acquire the relevant data to fill the gaps - such as historical accident rates, accident severities, alternative safety measures, comparisons with broadly similar stretches of road without a camera (or indeed with more or fewer other safety measures) and so on.
Personally I think we need to wait to see just what data we are given before we can make any definitive statements, but if we get reasonable information (and can find the rest out) then it should certainly improve the arguments on all sides.
So the lawbreakers who want the police to catch "real criminals" will have less to whine about. Oh wait, they'll carry on anyway.
Given our usual 600 murders/pa and 2500 road kills/pa, one could argue that public safety would be improved by putting police on the road, rather than on high profile murder cases.
given how much safer by design cars are today over 10 years ago, the roughly static RTA figures would indicate that the standard of driving is getting worse, and hence needs more policing to get nutters off the road
given how much safer by design cars are today over 10 years ago, the roughly static RTA figures would indicate that the standard of driving is getting worse, and hence needs more policing to get nutters off the road"
Given how much safer by design cars are today over 10 years ago, the roughly static RTA figures would indicate that the standard of driving is getting worse, and hence needs better driver training and education to reduce stupidity on the road rather than pumping more and more money into things aimed at the effect rather than the cause such as speed cameras, traffic calming and ludicrously sited traffic lights, roundabouts and wasting the police's time.
"Not safer for pedestrians, cyclists, horse-riders, and people in other cars."
Euro NCAP ratings for pedistrians would indicate otherwise.
However the uni-student cyclist, at night in dark clothing, with no lights on the bike, cycling the wrong way down the midle of a one way street, kind of defeats the design features.
For the last several years there have been many new safety standards introduced concerning impact reduction and safety improvements on targets outside the vehicle.
Not Safer for Pedestrians? Easing pedestrian injury when struck by cars has been affecting both design and regulation of new vehicles for several years now. I was told by one motor trade friend that the trend towards Plastic headlamps is partly due to this. I believe they even assess new designs with this in mind as part of vehicle type approval - which all new mass produced cars have to pass before mass production of a model begins.
Given the habit of pedestrians stepping off the kerb into moving traffic without looking I wonder that more are not killed or injured by their own stupidity/neglegence/inattention. We need jay-walking laws in the UK, but then there isnt a camera that can enforce that area so it would only be ignored anyway. As ever its easier to blame the driver, the driver who pays a huge amount of taxation to use the car and gets so little back in terms of adequate road maintenance etc
Cyclists are another bunch seemingly devoid of common sense, as I see far too many in dark clothing at dawn/dusk without lights, and even one recently at 10pm riding on the road unlit - a road that has a separate cycle path put in at great expense while highway repairs are neglected year on year. Thats without the idiots that ride 2 abreast on main roads or those cyclists carrying unsafe/insecure loads affecting their balance etc.
But then accidents are ALWAYS the motorists fault aren't they?
"RTA figures would indicate that the standard of driving is getting worse, and hence needs better driver training and education to reduce stupidity on the road"
Like by offering people caught by speed cameras the chance to go on a speed awareness course rather than get points you mean?
Yes some pedestrians step off pavements without looking, just like there are cyclists who cycle without lights and wearing black at night. But then there are motorists who speed and there are motorists who are a menace. Just because SOME people are like this, it doesn't mean ALL people are like this.
Some pedestrians (e.g. ME) take care when crossing roads.
Some cyclists (e.g. ME) wear reflective jackets, reflective trouser clips, reflective back-pack covers, have multiple reflectors on the bike and have 2 lights fore and two lights rear, complying to BS lighting and reflector standards.
Some motorists (e.g. ME) try to be considerate to others and not speed.
We don't need Jaywalking laws in this country because this country is not organised into blocks like in the USA, and there isn't a crossing every few yards we could use to cross, especially if you live in the country. It's hard enough to cross the road with the number of inconsiderate motorists around who just won't let people cross, even on zebra crossings.
Yes motorists pay a huge amount of tax. There are multiple reasons for this. One is that we don't have Hypothecation - in other words, the tax raised from the motorist is not ring-fenced to spend on the motorist. Almost none of are taxes are Hypothecated, in fact I can't think of one.
Yes motorists pay a lot of tax, but they cause a lot of pollution, congestion and other problems too. The alternative would be to reduce motoring taxes and vastly increase income tax to compensate. Would you prefer that?
"a road that has a separate cycle path put in at great expense"
There is no obligation to use a cycle path and sometimes it is inconvenient to do so, and on rare occasions, dangerous to do so.
"while highway repairs are neglected year on year."
Perhaps, but it's in a cyclist's interest as much as a car drivers to see potholes fixed. After all, if a bike hits a pot-hole, the cyclist is likely to end up much more injured than a car driver.
"Thats without the idiots that ride 2 abreast on main roads"
That's allowed, if perhaps not sensible
" or those cyclists carrying unsafe/insecure loads affecting their balance etc."
as opposed to motorists carrying unsafe/insecure loads affecting their and other people's safety.
"But then accidents are ALWAYS the motorists fault aren't they?"
No, but neither is it always the pedestrian's fault, the cyclists fault or the motorcyclists fault.
"Yes motorists pay a lot of tax, but they cause a lot of pollution, congestion and other problems too. The alternative would be to reduce motoring taxes and vastly increase income tax to compensate. Would you prefer that?"
Pollution? As opposed to a cow for example? Or a power station? Or a water treatment plant? That's really the only alternative you can think of?
Perhaps some of the congestion could be solved by taking some of the massive amounts of money paid by car drivers and investing to come up with an alternative form of transport or at least a transport policy that delivers ways to get the right things from A to B and means people have to drive cars less? According to government's own statistics solving such a thing would save billions in policing, hospitals, maintenance etc and so would pay for itself.
Buses and trains? A limited solution at best that could replace a fraction of the uses of cars (vans etc) but isn't being targeted at what those solutuions are good at anyway and yet is the only thing other than various "traffic calming" measures that government seems willing to throw money at as they provide worse and worse service at higher and higher prices to the consumer.
"No, but neither is it always the pedestrian's fault, the cyclists fault or the motorcyclists fault."
Actually by policy it turns out it IS always the car drivers fault. I know of a case recently where a car hit a cyclist who'd cycled across a give way line without stopping. The cyclist all but admitted as much in the claim against the car driver and the drivers insurance company agreed that it was the cyclist who was in the wrong. However despite this the insurance company resused to contest the cyclist's claim citing the unlikelihood of the case being found for the driver if it went to court - they admitted that if another car had been hit in those circumstances there wouldn't be any question, but that courts will in a majority of cases find for a cyclist or pedestrian over a driver no matter the circumstances.
Perhaps that may be a contributing cfactor in the increase I've noticed over the last decade or so in pedestrians wandering across the road without so much as a glance behind them just assuming any oncoming car will see them and stop.
"There is no obligation to use a cycle path and sometimes it is inconvenient to do so, and on rare occasions, dangerous to do so."
That one I agree with - in fact, being a cyclist in London myself, I wouldn't recommend it as a form of transport to anyone who does not enjoy the prostect of imminent death on a day-to-day basis. So much for alternatives to the car.
"cycle path put in at great expense"
I dont object to the cyclepaths.... I think they are a great idea - or at least would be if they were actually considered instead of being a nod from the government in the direction of "being green" - too often the government's pet policies collide in this area - I've seen a cyclepath put on a road then a few months later a bus stop on that path built out into the road so that the bus stopping at it blocks the road.
That not only seems to be a waste of money designed primarily to annoy car drivers at a stop that doesn't get enough people to warrant the extra pavement space, but then forces cyclists back out into the stream of largely unobservant cars who mostly blithly drive in a straight line and therefore too close to the bus stop to allow a cyclist room. Because most car drivers, if they notice a cycle path at all, then just assume the cyclist will be in it and therefore not a problem, that kind of fail in planning makes the cyclepath *more* dangerous for the cyclist than nothing at all.
I wouldn't object to the massive and ever increasing taxes on driving a car at all if there was any sign that even a percentage of it was spent on transport infrastructure that MADE SENSE instead of urinated away on pet projects to look good rather than do anything useful.
Hmm I think I'll put my soap box away and get a mop
"Like by offering people caught by speed cameras the chance to go on a speed awareness course rather than get points you mean?"
No I mean like by making the driving test actually include something other than theory and basic mechanical control of the car. Like teaching and testing situational awareness, like the abilty to judge speed and distance accurately and convergance rates, like skid training, like what a car feels like to drive in as many road conditions as humanly possible, like *demonstrating* physically stopping distances rather than it being basically theoretical.
Hardly perfect but even simulating such things with todays technology as part of driver training would vastly increase awareness and possibly get at least a few of the bad habits out *before* they become habits - otherwide you're just treating the symptom again. To fit a number of such simulators in every test facilty in the land would, I'd estimate, come in rather cheaper than any one of the national hate cars policies.
>> given how much safer by design cars are today over 10 years ago, the roughly static RTA figures would indicate that the standard of driving is getting worse
Not really, much of the 'safer by design' you speak of is only safer for the occupants of the car. Most RTA fatalities are not occupants of cars (they are pedestrians, cyclists, motorcyclists). Also don't forget that the roads are getting busier, so a static figure is actually a reduction.
The camera supporters, keep saying that speed is a factor in most accidents.
This is the same as saying that altitude is a factor in most planes hitting the ground.
True...... but totally useless in determining the true cause of the accidents.
Inappropriate driving (tail gating, driving too fast for the road condition (even when under the speed limit)) is the cause of many accidents.
The other factor is that according to insurance research, something like 1 in 4 drivers have deffective eye sight (i,e, they need glasses to see what they are running into, but are not wearing them)
Two things a revenue generating speed cam can't do anything about!
There's little in the way of a better deterrent than a plod in a car along the road. Even if the beggers have ANPR it's a help as it spots those without the usual tax, insurance and MoT, and a collar at the roadside is much more effective than a letter to a possibly false address. Maybe if they didn't have to spend half their time filling in reports for the stats they'd do more policing.
Recently I drove for 2 miles along a road with supposedly a speed limit of 60 at a mere 20mph. Two people were not so fortunate nearby, when I came back the other road had been closed as they'd come off the road at the bottom of the hill. The slush on ice did not help.
Police operated ANPR has several effects on public safety.
1. the number of crooks they catch who are wanted by the courts
2. drivers without insurance and MOTs are disproportionately represented in the accident stats (i.e. more likely to be involved/cause one)
Unfortunately they occiasonal work to well, I heard that Hants police had to give up after a couple of hours at the bottom of the M275, as they had managed to fill all the cells at Southsea nick.
there is a 30mph limit that was watched by speed cameras hiden inthe back of a van in a side street. Due to massive complains the council installed a 8foot square sign listing the number of addicents on this road in the past N years.
A FOI request by a local paper revealed accidents were mainly drunks tripping over the badly laid paving stones - almost all accidents counted had nothing to do with traffic or speed.
Only after a lot of people who had been "done" for 31 in a 30 zone did a protest along that road between the roundabouts at each end effectiveky gridlocking fboro did they remove the speed traps, misleading "stats" and install 30mph "slowdowns".
Finally the pub on that section of road closed a few years ago - which massively reduced the accident rate!
speed cameras are almost always a revenue stream for the ACPO businesses - they have very little to do with safety.
That'll be the same section of road where they nicked everyone by parking-up the monitoring van over the double-yellow lines in said side street, I'll bet. Yes, was clearly okay to violate one law to catch people breaking another!
It's all stopped now but what a lot of fuss for 6-700 yards of road and I did wonder why they bothered. Your logic is entirely reasonable!
BTW: monies raised by speeding fines don't go to ACPO but instead end up in the Treasury's pocket. Yes, arguably ACPO get some of this dosh - but then so do you in any state handouts you might qualify for!
The assumption that speed cameras are juicy revenue streams is in many cases a fallacy. You have to be pretty daft to get caught by a bright yellow camera (not happened to me yet, touch wood). Therefore the revenue for such a camera can be much lower than it's running cost. This is particularly the case for a camera that's actually doing it's job.
Considera camera that is "protecting" an accident black spot, what you don't want is the camera actually catching speeders, you want it preventing speeding. So a camera that's doing its job should be raising precisely nothing and costing quite a bit. The only way they could be said to be raising money is where government funding is more than the running cost of the camera. With the current government that will be a very rare situation.
"The assumption that speed cameras are juicy revenue streams is in many cases a fallacy."
A similar question came up on another site I read:
Which prompted me to go look and find:
Which would suggest the matter is rather more open to debate than you indicate.
... have got in ahead of the rush by deciding to ditch their speed cameras and save a quarter of a million quid a year on cameras which are mostly badly sited and do damn all for actual road safety.
Perhaps they'd like to use that money put a few more traffic Police out on the streets to catch the drunks and the idiot drivers instead which would do a lot more good.
"Road safety minister Mike Penning said that where taxpayers' money is spent on speed cameras it is right that information about their effectiveness should be made public."
That's a novel idea. Freedom of information. Who'd have thunk it would come from a Tory?
"...where taxpayers' money is spent on speed cameras it is right that information about their effectiveness should be made public."
I spotted that too. Presumably we can expect to be able to receive similar information about all government policies. Hopefully this means that the excuse "We can't provide that information due to commercial/contractual sensitivity" which means they won't tell you if a contracted out service is value for money or not is a thing of the past.
Because it is going to take a week to get the data and 3 months to apply spin before publication.
No - speed cameras do not make you drive slower. If you watch the majority of drivers, it is obvious that speed cameras make you drive slower for a very brief period of time (using very heavy braking, without looking in the rear view mirror) before accelerating hard up to a higher than normal speed to make up for the slowed section. On average I see people drive faster on roads immediately after speed cameras than they were before noticing the striped things!
Get rid of the lot of them and the rest of the nanny state infrastructure and bring back proper traffic cops, responsibility and discretion.