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PostPosted: Sat Apr 17, 2004 18:51 
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Caught in the speed trap


Guess - or if you're mathematically inclined, figure out - the answer to this tricky road safety question.

A 30-tonne logging truck travelling at 80km/h crashes, causing a hell of a mess. What speed would a one-tonne family saloon need to be travelling at to create the same level of mess?

a) 80km/h.

b) 240km/h.

c) 440km/h.

The answer (c - 440km/h) gives lie to the often heard road safety slogan "the faster you go the bigger the mess". The mess is not just about speed. Size does matter. To correct the small lie of omission, it's scientifically more accurate to say "the faster you go and the bigger you are, the bigger the mess".

But even that doesn't tell the whole story of what happens when big truck hits small car. The laws of physics do indeed dictate that the bigger you are and the faster you go, the bigger the mess - assuming you hit something as big as you are. But if you hit something smaller, the likelihood is that the small guy collects almost all the mess and the big guy doesn't suffer nearly as much. Which explains why some people like to drive 3-tonne SUVs.

Welcome to the complex and mixed-message world of road safety. For the record, the above example deals with what's known as kinetic energy (1/2 mass multiplied by velocity squared). It's the force that gets distributed into the impact of a crash and causes the destruction. The outcome of large mass hitting small car is a much bigger change of velocity of the smaller mass (the car crunched to halt and hurled backwards) - which means much greater destructive forces on the car.

The example illustrates one of the many partial truths about road safety that get Alan Wilkinson hopping mad with the Land Transport Safety Authority. So much so that the successful businessman with a PhD, former university lecturer, statistical programmer and prolific writer of letters to the editor who was once a co-leader of the Values Party and is now on the board of the Institute for Liberal Values, has been waging a one-man war. Problem is, no one is listening.

Probably because Wilkinson's thesis is so extreme. He believes the LTSA's "police-centric" focus on "rigid enforcement" of speed limits is counterproductive and that "the statistical evidence here and overseas is that higher speeds result in fewer death and injury accidents, rather than more".

Worse still is our large road safety advertising budget, which Wilkinson argues makes it difficult to challenge the prevailing "speed kills" message.

In truth, Wilkinson is not alone - as a visit to the UK website Safe Speed ( or the British Columbia site Sense ( will attest. Both sites groan with research, statistics and opinion supporting the view that speed is not the killer it's made out to be.

Sense, for example, suggests a general drop in road deaths is the result of air bags, anti-lock brakes, seat-belts and better road design rather than photo radar. And Safe Speed highlights UK Department for Transport statistics showing speeding is only the seventh most frequent cause of road accidents - claiming that inattention is the main cause, followed by "failure to judge another person's path or speed" and then "looked but did not see".

The propositions are dismissed outright by inspector John Kelly, operations manager of road policing support in New Zealand.

"Almost invariably, independent scientists and researchers around the world - in peer-reviewed articles published in reputable journals - find that speed is a major problem.

"We do not take too much notice of research published privately by pressure groups."

Kelly backs his position with a wealth of opposing research. For example: "Travelling just 5km/h faster in an urban area and 10km/h in a rural area was found to entail a comparable increase in risk of involvement in a casualty crash as driving with an illegal blood alcohol concentration."

He vigorously defends road safety policy as grounded in good research - and yes, that includes the new "speed cameras anywhere, anytime" regime.

"We know there are offenders who habitually speed between the signs. What we're saying to those people is that you can no longer be sure where the speed camera might be - so if you habitually speed you're going to have to change your habits."

He points to a Monash University Accident Research Centre review of Australian and international literature on traffic law enforcement. Among its conclusions: "The primary focus of speed enforcement should be on increasing surveillance levels, and hence the actual and the perceived risk of detection."

Interestingly, however, the review says "to maximise the benefits and community acceptance of speed camera operations it is important that enforcement is primarily targeted at accident locations where speed is known to be a causal factor".

Which is at odds with the "anywhere, anytime" policy and the removal of speed camera signs - a point not lost on AA director of public affairs George Fairbairn.

"We see that it's a retrograde step in removing the signs because it takes away that positive advice to motorists that this section of road has caused crashes in the past."

National MP Tony Ryall weighs in on the same issue - noting that none of the country's 10 worst road crash black spots has a permanent speed camera.

He points to "the snap-happiest speed camera in the country" - in Wellington's Ngauranga Gorge, where 24,835 vehicles were photographed exceeding the 80km/h speed in 2002 and yet the site has had only one fatality in the past 10 years.

Ryall notes, too, that 70 per cent of all speed camera tickets are for driving 11 to 15km/h over the limit and drivers travelling at 21km/h or more over the limit make up fewer than 10 per cent of those ticketed.

Associate Minister of Transport Harry Duynhoven rejects the criticism. "The aim is not to collect more revenue, it's to get people to drive at a safe speed."

Duynhoven was instrumental in ensuring a code of conduct for the use of cameras when they were introduced in late 1993. And Kelly says police, the LTSA, local roading authorities and the AA will continue to consult on the location of cameras. There are also discussions about placing general warning signs - that speed cameras are in operation throughout New Zealand.

But Kelly admits police will now have more discretion on placement.

"Cameras can be placed where they are less than obvious."

"Less than obvious" is apparently not the same as hidden, but does raise concerns.

"Does this give the police the opportunity to operate in a semi-hidden manner?" asks the AA's Fairbairn.

"I think they are de facto hidden cameras - no doubt about that," says Ryall.

Which brings us back to Wilkinson, who has challenged a key piece of LTSA research related to the new camera policy - the notorious Midland hidden camera trial that began in May 1997 and finished in March 1999.

Notorious because although the research concluded that the open-road speed fell by 2.3km/h, the crash rate fell by 11 per cent and casualties by 19 per cent, the then Transport Minister, Mark Gosche, scrapped the Waikato pilot in 2000 because he did not believe it had cut speeding or road deaths.

Wilkinson became involved when he saw reports that hidden speed cameras were back on the agenda. Pushing the case was LTSA director David Wright, saying suggestions that trials in the Waikato were inconclusive was "one of the great myths".

To cut a long story short, Wilkinson got hold of the original Midland report, noticed some odd-looking graphs which were not in the published version - and then did his own graphing of the raw data.

Much to his surprise, when he compared the Midland data to the rest of the country, he found the hidden speed cameras had made no difference to casualties - if anything they actually increased during the trial period.

So how did the researchers arrive at their quite opposite conclusion? Wilkinson says it comes down to the statistical model which produced a positive effect for the trial when the "trend term was permitted to predict a long-term stable trend of crashes increasing in the trial area relative to the rest of New Zealand".

But, based on the historical data, he says that was "a dubious presumption" because there was a significant sharp decline in crashes for the rest of New Zealand from November 1995 to June 1997 "which was neither reflected in the Midland data nor persistent through the rest of the period".

Fairbairn is more succinct. "I think it was using statistics to prove your point." He says there were a number of other year-to-year variables in the Waikato trial that caused irregularities. The LTSA's Wright doesn't say much about the trial - except that the auditor-general did a review of the methodology and found it "robust". He supports the "anywhere, anytime" policy.

Meanwhile, Wilkinson has graphed more raw data which shows - again surprisingly - that greater police visibility on the roads, a policy which began in 2000, also has little or no effect on open road casualties. Like Canada, he finds the road toll in New Zealand is coming down regardless - likely because of better cars, roads and emergency services.

Most of this is, of course, rejected by the LTSA. Its graphs show how various safety campaigns and policies have helped reduce road carnage - and in particular reduced the mean speed.

Despite acknowledging that 85 per cent of all accidents and 75 per cent of fatalities happen under the speed limit, both Wright and Kelly maintain speed is still the number one problem. Both also acknowledge that speed in this instance means speed that is "too fast for the prevailing conditions" and not necessarily over the speed limit.

True, they agree, much of that can't be caught on a speed camera, but it can be caught by traffic patrols. And yes, there are always many factors that cause accidents. Duynhoven sees poor judgment as the number one cause of accidents - a category that's not on the LTSA's list.

In Wright's world, the cold hard fact is that "travelling at 120km/h versus 100km/h means you about double your risk of being killed in a crash".

And as Kelly, and the latest TV ads, point out, "it takes you much more time to stop the faster you go".

Fairbairn, Ryall and Wilkinson all argue - in varying degrees - that there is too much focus on speed policing and the money could be better spent on things such as improving roads, greater police presence or mandatory side airbags in new cars.

All stress targeting inattentive drivers and that driving to the conditions is a more important message than not driving too fast.

As Fairbairn puts it: "There is unfortunately too much of a view that the open-road speed limit is 100km/h and that come hell or high water you should still drive at 100km/h. But we have many secondary roads in many rural areas where 100km/h is too high and people don't always adjust to conditions, be it in the wet or at night."

To which criticism both Duynhoven and Police Minister George Hawkins cite numerous initiatives under the three "Es" - engineering, education and enforcement - that make up road safety policy.

But looking at the $81.3 million in fines collected by police radar and speed cameras in 2002 (not including late-payer fines collected by the courts which were unavailable at press time), you can't help thinking speed enforcement rules the roads.

Hawkins tells an undeniable truth when he says: "What we really want to do is to get people to slow down."

Paul Smith
Our scrap speed cameras petition got over 28,000 sigs
The Safe Speed campaign demands a return to intelligent road safety

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