Speed cameras save lives

[Asguard]

Concidering the number of people here who have stated that the whole point of speed cameras is goverment revinue i thought this might be interesting. I have delibratly placed it in science and society because of the evidence to show that view is (to borrow a phrase from tony abbott) "compleate crap"

Speed cameras for the prevention of road traffic injuries and deaths
Wilson C, Willis C, Hendrikz JK, Le Brocque R, Bellamy N
Cochrane Collaboration

Plain Language Summary
Do speed cameras reduce road traffic crashes, injuries and deaths?
Road traffic crashes are a major cause of death and disability. The speed at which a vehicle travels is an important determinant of injury; the faster the vehicle is travelling, the greater the energy inflicted on the occupants during a crash, and the greater the injury.

Excessive speed (driving faster than the posted limit or too fast for the prevailing conditions) has been found to contribute to a substantial number of crashes. It is predicted that, if the number of speeding drivers is reduced, both the likelihood and severity of a crash will be lowered. Therefore, interventions aimed at reducing traffic speed are considered essential to preventing road injuries and deaths. The enforcement of safe speeds with speed cameras and associated automated devices is one such measure.

To evaluate the effectiveness of speed cameras, the authors examined all eligible studies, that is, studies that met pre-set standard criteria. We analysed the effect of speed cameras on speeding, road traffic crashes, injuries and deaths by comparing what was happening in road areas before the introduction of speed cameras and after their introduction, and also by analysing what was happening in comparable road areas where no speed cameras were introduced during the study period.

The authors accepted a total of 35 studies for review which met the pre-set criteria. All studies reporting speed outcomes reported a reduction in average speeds post intervention with speed cameras. Speed was also reported as either reductions in the percentage of speeding vehicles (drivers), as percentage speeding reductions over various speed limits, or as reductions in percentages of top end speeders. A reduction in the proportion of speeding vehicles (drivers) over the accepted posted speed limit, ranged from 8% to 70% with most countries reporting reductions in the 10 to 35% range.

Twenty eight studies measured the effect on crashes. All 28 studies found a lower number of crashes in the speed camera areas after implementation of the program. In the vicinity of camera sites, the reductions ranged from 8% to 49% for all crashes, with reductions for most studies in the 14% to 25% range. For injury crashes the decrease ranged between 8% to 50% and for crashes resulting in fatalities or serious injuries the reductions were in the range of 11% to 44%. Effects over wider areas showed reductions for all crashes ranging from 9% to 35%, with most studies reporting reductions in the 11% to to 27% range. For crashes resulting in death or serious injury reductions ranged from 17% to 58%, with most studies reporting this result in the 30% to 40% reduction range. The studies of longer duration showed that these positive trends were either maintained or improved with time.

The quality of the included studies in this review was judged as being of overall moderate quality at best, however, the consistency of reported positive reductions in speed and crash results across all studies show that speed cameras are a worthwhile intervention for reducing the number of road traffic injuries and deaths. To affirm this finding, higher quality studies, using well designed controlled trials where possible, and studies conducted over adequate length of time (including lengthy follow-up periods) with sufficient data collection points, both before and after the implementation of speed cameras, are needed. As none of the studies were conducted in low-income countries, research in such settings is also required. There is a greater need for consistency in methods, such as international standards for the collection and reporting of speed and crash data and agreed methods for controlling bias in studies. This would allow more reliable study comparisons across countries, and therefore greater ability to provide stronger scientific evidence for the beneficial effects of speed cameras.




Abstract
Background
It is estimated that by 2020, road traffic crashes will have moved from ninth to third in the world ranking of burden of disease, as measured in disability adjusted life years. The prevention of road traffic injuries is of global public health importance. Measures aimed at reducing traffic speed are considered essential to preventing road injuries; the use of speed cameras is one such measure.

Objectives
To assess whether the use of speed cameras reduces the incidence of speeding, road traffic crashes, injuries and deaths.

Search strategy
We searched the following electronic databases covering all available years up to May 2010: the Cochrane Library, MEDLINE (WebSPIRS), EMBASE (WebSPIRS), TRANSPORT, IRRD (International Road Research Documentation), TRANSDOC (European Conference of Ministers of Transport databases), Web of Science (Science and Social Science Citation Index), PsycINFO, CINAHL, EconLit, WHO database, Sociological Abstracts, Dissertation Abstracts, Index to Theses.

Selection criteria
Randomised controlled trials, interrupted time series and controlled before-after studies that assessed the impact of speed cameras on speeding, road crashes, crashes causing injury and fatalities were eligible for inclusion.

Data collection and analysis
We independently screened studies for inclusion, extracted data, assessed methodological quality, reported study authors' outcomes and where possible, calculated standardised results based on the information available in each study. Due to considerable heterogeneity between and within included studies, a meta-analysis was not appropriate.

Main results
Thirty five studies met the inclusion criteria. Compared with controls, the relative reduction in average speed ranged from 1% to 15% and the reduction in proportion of vehicles speeding ranged from 14% to 65%. In the vicinity of camera sites, the pre/post reductions ranged from 8% to 49% for all crashes and 11% to 44% for fatal and serious injury crashes. Compared with controls, the relative improvement in pre/post injury crash proportions ranged from 8% to 50%.

Authors' conclusions
Despite the methodological limitations and the variability in degree of signal to noise effect, the consistency of reported reductions in speed and crash outcomes across all studies show that speed cameras are a worthwhile intervention for reducing the number of road traffic injuries and deaths. However, whilst the the evidence base clearly demonstrates a positive direction in the effect, an overall magnitude of this effect is currently not deducible due to heterogeneity and lack of methodological rigour. More studies of a scientifically rigorous and homogenous nature are necessary, to provide the answer to the magnitude of effect.

Viewed 26/09/11 at 22:07

If anyone wants to go into this review deeper here is the full artical
http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD004607.pub4/full

Wether you can access it may depend where you are, Australia pays for a country wide licence to cochrane (so that everyone has access to the highest quality health care infomation) but not all countries do

 

[adoucette]

The problem with these studies is they all look at stats for where the cameras are, but drivers know where speed cameras are and avoid them, thus they take their accidents with them when they change routes.

 

[Asguard]

The problem with these studies is they all look at stats for where the cameras are, but drivers know where speed cameras are and avoid them, thus they take their accidents with them when they change routes.

you know you really shouldnt make assumptions about scientific studies without READING them

Localised crash effects
The result for 'all crashes' showed pre/post percent reductions ranging from 8% in Victoria (AU VIC 1) to about 49% in Arizona (US Arizona 1) with all other studies reporting this outcome showing reductions in the 14% to 25% range. For crashes resulting in deaths or serious injuries pre/post percent average reductions of 11% at or less than 500m distance and 13% at or less than 1km distance were reported by (GB 30mph Roads Nationwide), reductions of 11.5% were seen in Victoria (AU VIC 2) and reductions of 38%, 42% and 44% were reported by (AU QLD 2; GB Nationwide and GB Norfolk) respectively. Whilst a pre/post reduction of 22% in personal injury crashes at camera sites was found in one large study in (GB Nationwide) no significant reduction in injury crash frequency or severity was found within one km of camera sites, either in urban or rural areas, in another sizeable study in Victoria (AU VIC 1) as a result of camera site operations. However in this latter study a localised effect of 8.4% in pre/post injury crash reduction was found for all urban roads as a result of the influence of receipt of traffic infringement notices (TINs). A reduction of about 50% in injury crashes was reported by South Wales (GB South Wales) and the Cambridge study (GB Cambridge) reported a pre/post 45.74% reduction in injury crashes within 250m from camera sites and a lesser but significant 20.86% reduction inside a 2 km radius from the camera.


Generalised crash effects
Outcomes reported were pre/post reductions in 'all crashes' ranging from 9% in Christchurch (NZ Christchurch) to 35% in the Netherlands (NL Netherlands), with all other studies reporting reductions in the 11% to 27% range. For crashes resulting in death or serious injury pre/post percent reductions ranged from 17% in British Columbia (CA British Columbia) to 58% in Tasmania (AU Tasmania) with all other studies reporting this outcome in the 30% to 40% reduction range. For injury crashes pre/post percent reductions ranged from 17% in British Columbia (CA British Columbia) and New Zealand (NZ Nationwide) to 23% reductions for Denmark (DK Denmark) and Hong Kong (HK Hong Kong).

For the outcome 'all crashes' 14 relative crash ratio (RCR) could be calculated for 12 studies and ranged in value from 0.53 (95% CI = 0.39-0.73) in Arizona (US Arizona 1) to 0.95 (95% CI = 0.73-1.22) in Vancouver (CA Vancouver B.C.) denoting reductions of 5% to 47% for 'all crashes' relative to controls. Using CL as an indication of statistical significance, eight RCRs were significant and six were non-significant. The RCR could be calculated for 11 studies reporting 'injury crash' results and ranged from 0.57 (95% CI = 0.32-1.03) in Arizona to 0.86 (95% CI =0.42-1.02) in Hong Kong (HK Hong Kong), of which two were significant and nine non-significant. For the few studies (4) where the RCR could be calculated for 'fatalities', the result ranged from 0.00 (95% CI =0.00-0.35) in New South Wales (AU NSW 2) to 0.72 (95% CI = 0.36 -1.08) in Tasmania (AU Tasmania). In the (GB 30mph Roads Nationwide) study both fatal and serious injury crashes were reported together. The RCR in this latter study, for at or less than the 500km distance was 0.69 (95% CI = 0.57-0.69) with an RCR 0.73 (95% CI = 0.53-0.93) calculated for ≤ 1km distance from camera sites. Using CL as an indication of statistical significance, three of the five RCRs were significant and two non-significant. Only one study (DE Germany) gave enough information to calculate the summary statistic percentage crash relative rates ratio (PSRRR), which was 0.44, CI incalculable. In summary, of the 30 RCRs calculated, 13 were significant and 17 were non-significant.

Further details of crash outcomes can be seen in the 'Characteristics of included studies' section and in the Summary of CBA studies - Crash Outcomes ( Table 4) and the Summary of CBA studies - Speed Outcomes ( Table 3) tables.

http://onlinelibrary.wiley.com/doi/10.1002/14651858.CD004607.pub4/full

 

[chimpkin]

Maybe.

I'm given to understand they reduce inter-intersection collisions, but increase rearends.

Rearending is safer; the car's got more protection in the back...

Sorry, posting prior to caffeine here, always a risk.

 

[cosmictraveler]

Angry German Drivers Take Revenge on Speed Cameras.

A 22-year-old man from the Peine area had to wave goodbye to his driving license and was fined heavily after repeatedly hurtling past a speed camera while making an obscene gesture with his middle finger. The motorist had taped over the car's registration plate in a bid to escape identification and it was only after he was involved in an accident that police managed to track him down

A speed trap installation on the A 44 highway near Kassel also became a hate object for a number of motorists. The first device was stolen by traffic rowdies, while a 19-year-old took an axe to its replacement. Police found the perpetrator by matching the DNA of blood traces left at the scene of the crime.

In order to avoid being charged, one speeding driver stopped his car long enough to rip out all the speed limit signs he could find along a stretch of road and tossed them into a nearby ditch. Officers came across them several days later.

The speed traps also pay for themselves quickly. One camera near the small town of Hildesheim registered more than 5,000 speeding motorists during its first two months on the job -- triggering an income of 45,000 euros in fines.

http://www.google.com/url?sa=t&sour...Ke2NwD&usg=AFQjCNF5B2bFESvrVivkx2s9yErkUub6Gw

Yes, the photo above is real: It is Animal—from The Muppets—driving a British Audi while speeding through a German road. The famous pink drummer is driving the police there absolutely crazy, because he keeps doing it again and again. Or better said, the real driver is, using a low-tech approach to take advantage of a weak point of the radar cameras. I don't know about you, but this image makes me laugh out loud. The German police, however, wasn't amused when they explained to the press how the whole joke worked and how they couldn't fine the driver because of it.

 

[Fraggle Rocker]

There are a lot of ways to save lives. Everyone could just walk, or better yet just stay home. There might be a problem getting food if they don't go to work, but hey we'll let the government solve that problem too, right?

My point is that it is necessary to perform risk analysis and risk management before one can rationally decide which risks to accept, which to mitigate, and which to avoid. The "speed kills" nannies are hysterical, not rational, so what they say must be taken with a grain of salt.

For example, if everyone here in the Washington DC region drove at 55mph or 65mph (the speed limits on most highways in Maryland and Virginia), instead of 75-80mph, which is the typical rate of traffic flow, it would take everyone significantly more time to reach their destinations. The nannies refuse to accept the reality that time is money. If you waste an additional 10-15 minutes every day going to and from work, what other activity in your life is going to be shortened to compensate? I suppose those people would automatically say "television" because most nannies think TV is a waste of time, but recreation is an important part of our lives. Without it we won't sleep as well, our work will suffer, and the economy will suffer. If people get home from work later they'll have to pay more money to their babysitters. They may not have time to cook so they'll have to eat fast food, which is not as nutritious and may make them fat. They'll have to get up earlier in the morning and leave for work earlier, which means they won't be able to see their own garden in the daylight. This will cause depression, which will reduce the quality of their work, increase stress among their office-mates, and make them worse parents.

Life is complicated. Compromises are inevitable. In many cases both choices are less than optimum. We have to be rational in order to make rational choices.

Screaming about fast driving, like an angry parrot who doesn't have anything else to say, is not rational.

 

[adoucette]

you know you really shouldnt make assumptions about scientific studies without READING them

I can't read the ones you posted, but I have read other studies on them in the US and they tend to just make drivers switch to other routes, and they do take the accidents with them. (note, this presumes that there ARE other routes, and in the US that is usually the case, in smaller areas saturated with cameras that might not be the case)

Still, even for this examination of 35 studies, the authors themselves say that quoting any figures about a positive impact is not supportable by the limited evidence.

whilst the the evidence base clearly demonstrates a positive direction in the effect, an overall magnitude of this effect is currently not deducible due to heterogeneity and lack of methodological rigour

Arthur

 

[adoucette]

Maybe.

I'm given to understand they reduce inter-intersection collisions, but increase rearends.

Rearending is safer; the car's got more protection in the back...

Sorry, posting prior to caffeine here, always a risk.

I think you are referring to Red-Light cameras, not Speeding Cameras.

Arthur

 

[billvon]

There are a lot of ways to save lives. Everyone could just walk, or better yet just stay home. There might be a problem getting food if they don't go to work, but hey we'll let the government solve that problem too, right?

Government has already "solved the problem" of how to get to work. They built you a road.

My point is that it is necessary to perform risk analysis and risk management before one can rationally decide which risks to accept, which to mitigate, and which to avoid.

Agreed. Which is the purpose of analyses like the one above.

For example, if everyone here in the Washington DC region drove at 55mph or 65mph (the speed limits on most highways in Maryland and Virginia), instead of 75-80mph, which is the typical rate of traffic flow, it would take everyone significantly more time to reach their destinations.

Yes. And fatal crashes and injuries would decline. Which is more important? That's a question for the operators of the road (i.e. the state) to decide.

Screaming about fast driving, like an angry parrot who doesn't have anything else to say, is not rational.

Which is as valid as saying "crying like a spoiled child about taking a few minutes longer to get to work is not rational."

 

[KilljoyKlown]

There are a lot of ways to save lives. Everyone could just walk, or better yet just stay home. There might be a problem getting food if they don't go to work, but hey we'll let the government solve that problem too, right?

My point is that it is necessary to perform risk analysis and risk management before one can rationally decide which risks to accept, which to mitigate, and which to avoid. The "speed kills" nannies are hysterical, not rational, so what they say must be taken with a grain of salt.

For example, if everyone here in the Washington DC region drove at 55mph or 65mph (the speed limits on most highways in Maryland and Virginia), instead of 75-80mph, which is the typical rate of traffic flow, it would take everyone significantly more time to reach their destinations. The nannies refuse to accept the reality that time is money. If you waste an additional 10-15 minutes every day going to and from work, what other activity in your life is going to be shortened to compensate? I suppose those people would automatically say "television" because most nannies think TV is a waste of time, but recreation is an important part of our lives. Without it we won't sleep as well, our work will suffer, and the economy will suffer. If people get home from work later they'll have to pay more money to their babysitters. They may not have time to cook so they'll have to eat fast food, which is not as nutritious and may make them fat. They'll have to get up earlier in the morning and leave for work earlier, which means they won't be able to see their own garden in the daylight. This will cause depression, which will reduce the quality of their work, increase stress among their office-mates, and make them worse parents.

Life is complicated. Compromises are inevitable. In many cases both choices are less than optimum. We have to be rational in order to make rational choices.

Screaming about fast driving, like an angry parrot who doesn't have anything else to say, is not rational.

There is a logical solution to the problem you are complaining about, and that is to change the speed laws on the open roads. I agree with you in that today’s cars are relatively safe at speeds up to 85 mph on the open road. The government knows what the average traffic speed is and to post cameras and start ticketing people just to make more income in the name of saving lives an improving gas mileage is just plain wrong. However in the cities and towns most accidents do happen at intersections and everybody does know where the cameras are because of the flash that lets you know they are working long before you need to slow down, so rear end accidents should not be a problem either.

Traffic cams also have secondary benefits in the any accidents that do happen at an intersection have a video record that can be followed up on. Also, I know that everybody knows from watching TV, the police are able to track criminals via these traffic cams which also time stamps every image. So if we can adjust our laws a little bit we can improve traffic safety without pissing off an entire driving population.

 

[Asguard]

I find it facinating the people in this thread who think that "because i said so" is a vaild counter argument to a cochrane review. For those who dont know cochrane reviews are concidered the gold standed for health resurch, there is no higher grade of evidence. This shouldnt mean they are above critisium but that critisium should contain more evidence than "because i said so" (notice this thread is in a SCIENCE section), especially comming from someone who holds himself up as a scientist (FR).

Furthermore on your derogitory comments about road saftey FR is just sad comming from a person living in a country with one of the most appaling road tolls IN THE WORLD. Now before you jump up and down about how big the US is lets compare it to both Australia (with a comparitivily large area and therefore a population which spends most of its time on the road) and the UK (which has quite a dense population)

The first number is Road fatalities per 100,000 inhabitants per year
The second is Road fatalities per 100,000 motor vehicles
The third Road fatalities per 1 billion vehicle-km

Australia 5.2, 8, 6
UK 3.59, 7, 5.7
US 12.3, 15, 8.5

Now why the difference? in Australia its very easy to say why those numbers are so low, we spend HUGE amounts of money and resorces on road saftey because they were so high.

http://www.abs.gov.au/ausstats/abs@...9AFD4E13D7DA281FCA2569DE0028B40C?OpenDocument

Further more FRs hysterical comments fly in the face of reality, i wonder does he concider all health resurch to be "" nannies" and "hysterical, not rational, so what they say must be taken with a grain of salt". Its a facinating view point

Lets see who is intrested in road saftey

The WHO for instance: http://www.who.int/world-health-day/previous/2004/en/

Very histerical organisaiton

The UN itself http://www.who.int/roadsafety/en/
Infact there was a resolution in the general assembly dealing SPESIFICALLY with road saftey because it is concidered to be such an important issue.

I leave it to you to read through this list of those involved in the UN road saftey collaboration

http://www.who.int/roadsafety/about/partners/en/index.html

Further more cochrane themselves oviously concider this to be a health issue or it would never have alowed a review (they ONLY deal with health resurch)

Now FR may concider it irrelivent but concider this:

Worldwide it was estimated in 2004 that 1.2 million people were killed (2.2% of all deaths) and 50 million more were injured in motor vehicle collisions.[1][39] India recorded 105,000 traffic deaths in a year, followed by China with over 96,000 deaths.[40] This makes motor vehicle collisions the leading cause of injury death among children worldwide 10 – 19 years old (260,000 children die a year, 10 million are injured)[41] and the sixth leading preventable cause of death in the United States[42] (45,800 people died and 2.4 million were injured in 2005).[43] In Canada they are the cause of 48% of severe injuries.[44]

http://en.wikipedia.org/wiki/Traffic_collision#Fatality

Results The leading causes of death in 2000 were tobacco (435000 deaths; 18.1% of total US deaths), poor diet and physical inactivity (400000 deaths; 16.6%), and alcohol consumption (85000 deaths; 3.5%). Other actual causes of death were microbial agents (75000), toxic agents (55000), motor vehicle crashes (43000), incidents involving firearms (29000), sexual behaviors (20000), and illicit use of drugs (17000).

http://proxy.baremetal.com/csdp.org/research/1238.pdf

 

[adoucette]

The first number is Road fatalities per 100,000 inhabitants per year
The second is Road fatalities per 100,000 motor vehicles
The third Road fatalities per 1 billion vehicle-km

Australia 5.2, 8, 6
UK 3.59, 7, 5.7
US 12.3, 15, 8.5

Now why the difference?

Predominately because CARS are safer and roads are better engineered.

Fatalities per billion kilometers

Lap Seat belts became common starting in the late 60s, improving to 3 point belts in the 80s along with crumple zones, impact absorbing steering wheels, saftey glass, side impact bracing and then belts for rear seat passengers then added driver side air bags in the 90s followed by passenger side air bags, massive amounts of refinements from crash testing etc etc.

Arthur

 

[Asguard]

Predominately because CARS are safer and roads are better engineered.

Lap Seat belts became common starting in the late 60s, improving to 3 point belts in the 80s along with crumple zones and improvement of interior design and side impact bracing and then belts for rear seat passengers then added driver side air bags in the 90s followed by passenger side air bags, massive amounts of refinements from crash testing etc etc.

Arthur

evidence please that that is the only difference

Especially concidering that the worst drivers tend to drive the worst cars, ie P-platers cant aford new cars with all the best saftey features. Further more if that was the only factor then as the percentage of 4 wheel drives goes up so should the road toll (as a percentage) because until recently they wernt concidered passanger cars so didnt conform to the saftey standeds.

Lastly you dont think those trials take those factors into account? If not, prove it

 

[adoucette]

Because EVERY country showed the huge decline....

 

[Asguard]

Because EVERY country showed the huge decline....

sooo you are holding anacdotal evidence as greater than cochrane reviews. Nice

 

[adoucette]

Those Charts are not anecdotal evidence and the vast majority of the decline predates almost all use of Speed Cameras.

But let me repeat what the Cochrane review actually said:

whilst the the evidence base clearly demonstrates a positive direction in the effect, an overall magnitude of this effect is currently not deducible due to heterogeneity and lack of methodological rigour

On the other hand (from Wiki):

In June 2011, the New South Wales (NSW) government were reported to have raised A$350 million over the previous five years from speed cameras
It is predicted that the South Australia (SA) government will raise A$138 million in the 2011-12 year from speed limit enforcement activities. They raised A$114 million in 2010-11
The Victoria government forecasts that a revenue of A$245 million will be raised from fines levied on drivers breaking Victorian road rules, a large proportion being from speed limit enforcement, in 2011.[50]

So while the magnitude of the effect is not deducable clearly these things raise a lot of money.

http://en.wikipedia.org/wiki/Speed_limit_enforcement

 

[adoucette]

Since you put so much stock in the Cochrane reviews I find it interesting that they did screw this up:

In the (GB 30mph Roads Nationwide) study both fatal and serious injury crashes were reported together. The RCR in this latter study, for at or less than the 500km distance was 0.69 (95% CI = 0.57-0.69) with an RCR 0.73 (95% CI = 0.53-0.93) calculated for ≤ 1km distance from camera sites.

That was actually for a 500 METER distance.

Meaning, as I originally pointed out, that none of the tests looked at impacts on alternate routes away from the where the cameras were installed.

Finally, it's interesting that they only give the crash data in percentages.

Since it can be presumed that at any given site the actual number of crashes would be minimal, even a tiny change will yield high percentages.

In fact it points out, that most of the tests produced relative crash results which were not statistically significant (17 out of 30).


It's a way of using numbers to make a point without actually lying about it.

 

[Asguard]

Since you put so much stock in the Cochrane reviews I find it interesting that they did screw this up:




That was actually for a 500 METER distance.

Meaning, as I originally pointed out, that none of the tests looked at impacts on alternate routes away from the where the cameras were installed.

Finally, it's interesting that they only give the crash data in percentages.

Since it can be presumed that at any given site the actual number of crashes would be minimal, even a tiny change will yield high percentages.

In fact it points out, that most of the tests produced relative crash results which were not statistically significant (17 out of 30).


It's a way of using numbers to make a point without actually lying about it.

firstly that was just one out of the generalised studies and secondly would you like to show where you got that it was ment to be m insted of km from

 

[adoucette]

Really?

You think that Speed Cameras have a measurable effect 500 km distant?????

LOL

From the GB 30mph Roads Nationwide test referred to:

Interventions: Fixed overt cameras, which included warning signs. Crash data were collected for all crashes occurring up to 1 km either side of the cameras.

That and the fact that other similar studies also published 500 m and 1 km results.

Finally other tests do indeed refer to "Traffic Migration", either explicitly or sort of hidden in their data.

In the NL Friesland study there was much lower traffic volumes compared to the treatment group (3800 versus 7200 vehicles per hour), or roughly half the people found a new route because as they pointed out: Each enforced road had a posted road sign warning that stated speed camera enforcement was possible.

Arthur

 

[Asguard]

so in other words it wasnt a stuff up, you just dont like it. You got your doctorate where exactly?