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Injury Trends - ACC Spins the Facts You can't convince a believer of anything; for their belief is not based on evidence, it's based on a deep-seated need to believe. - Carl Sagan


From: Alan Wilkinson
Sent: Monday, 11 October 2004 1:24 p.m.
Subject: Increasing traffic injuries

Hon Ruth Dyson
Minister for Accident Compensation Corporation

Copied to: Rt Hon Helen Clark, Prime Minister

Dear Ms Dyson

Since the police Highway Patrol and the policy of rigid enforcement of speed limits were introduced at the end of 2000, ACC traffic injury claim statistics as well as LTSA injury statistics showed an immediate and very significant trend upwards. (See graphs attached.) This is despite huge increases in speeding fines, sharply reduced average speeds and no significant change in fatality trends.

The turnaround from what was previously a steady decline now indicates that traffic injury claims are 2-3 times higher than they would have been had this catastrophic misdirected enforcement policy not been implemented.

What analysis and data breakdowns does ACC have regarding the reasons for this very serious and costly adverse trend?

What does the government intend to do to reverse it? What lessons have been learnt from this mistake?

Yours sincerely

Alan Wilkinson 


4 November 2004

Dear Mr Wilkinson

Thank you for your letter of 11 October 2004, in which you raise your concerns regarding motor vehicle accident trends since the end of 2000.

ACC advises me that the payment data, upon which you have based your conclusions, can be impacted on by factors other than the number of crashes.  Changes in legislation, for example, impact on entitlement to certain payment types.  ACC's data regarding new claims registered per month in the Motor Vehicle Account since July 1996 shows that the upward trend in the volume of new claims received began around mid-1999.  The trend also appears to be more gradual than you suggest.  However, it is important to note that ACC's claim data is not necessarily a true representation of all injuries from road crashes, as there is a dependence on people registering a claim under the scheme.

The increase in motor vehicle injuries are also related to exposure to risk and the level of that risk.  During the period 2000-2003, New Zealand's population increased by 3.4% and the amount of travel increased by 8.7%.   These changes have resulted in an increase in the number of people exposed to risk on our roads and the length of that exposure.  Assuming ther is no change in crash risk over the period it would be reasonable to assume the volume of injuries would increase due to this increased exposure.

ACC is a member of the National Road Safety Committee and works with the members of this committee at both a policy level and an operational level, to reduce injuries on New Zealand's roads.

ACC is committed to injury prevention, which includes the promotion of road safety.  The ACC Stop Bus programme began in May 1999, in partnership with the New Zealand Police.  ACC's support for the programme is focussed on raising public awareness.  The aim of the programme is to reduce injuries and fatalities arising from alcohol related crashes.  There is currently one Stop Bus for every police district around the country.  The programme came about because drink driving crashes kill and injure thousands of New Zealanders every year.  Last year, ACC paid over $30 million to claimants for injuries sustained in alcohol-related crashes.  The Land Transport Safety Authority (LTSA) data gathered since the programme began, shows that there has been more than a 4% decrease in alcohol-related crashes (down from 18% to 13.2%).

ACC is also involved with the "Down With Speed" campaign, which aims to highlight speeding behaviour for key audiences and organisations.  The Corporation also works in conjunction with the New Zealand Police and Road Safety Co-ordinators, to promote the use of safety belts.

Thank you again for your letter.  I trust that my response has addressed you concerns.

Yours sincerely

Hon Ruth Dyson

-----Original Message-----
From: Alan Wilkinson
Sent: Monday, 8 November 2004 2:05 p.m.
Subject: RE: FW: Increasing traffic injuries

Hon Ruth Dyson
Minister for ACC

Copied to: Rt Hon Helen Clark, Prime-Minister.

Dear Ms Dyson

Thank you for your letter of 4 November 2004 responding to concerns over sharply rising motor vehicle injury accident trends since 2000.

Unfortunately the analysis provided to you by ACC is quite untenable for the following simple reasons.

1. The upward ACC injury trend data since 2000 is exactly confirmed by the police/LTSA traffic injury data which come from a completely independent source. There can be no question it is real and not an artifact of ACC legislative changes.

2. The increase in injuries on both data sources far exceeds the increases in vehicle travel or population over the period. For instance, had the trend prior to 2000 continued for weekly compensation injury claims these would have totalled about 1000 for the year to June 2004. The actual number was 3442, greater by a factor of 3.4. The population increase factor of 1.034 and the vehicle travel increase factor of 1.087 are completely negligible in comparison. (Moreover, the period 1994-2000 also experienced growth, yet the annual injuries were declining strongly and very consistently despite that growth.)

3. If the upward trend had begun significantly in 1999 it would have showed in the data for the year ended June 2000. It doesn't - that result is well within the normal deviation around the downward trend line for the seven years ended June 1994 thru 2000. It is crystal clear that the year ended June 2001 marks the start of a sharp upward movement. Monthly fluctuations are much greater than annual ones and cannot be taken as representative of significant changes in trends unless confirmed over much longer periods. Unfortunately, LTSA and police representatives persistently ignore this fact and hail with a big fanfare each favourable fluctuation while ignoring the next month's reversal.

4. If true (and LTSA-sourced causal factor data must be taken with a large grain of salt) that the alcohol-related crashes have reduced from 18% in 1999 to 13.2% in 2004, this only increases the magnitude of the failure of the "speed kills" programme, since despite this reduction, the overall injury trend has risen so greatly in that period.

Good intentions are insufficient. The ACC must be objective and honest about results. It doesn't matter what people believe causes accidents. What matters is what actually does cause them.

Recent detailed and extensive academic US traffic accident research I have examined fails to uphold any clear relationship between speed and crash frequency. For example, a comparison of crash frequencies on multi-lane highways failed to find any difference between fast and slow lanes. A comparison of male and female drivers found that on average males prefered to drive 7 mph faster than females. However, males and females had similar frequency of crashes per distance driven. Other studies failed to find any relationship between average speed immediately before the crash and the likelihood of a crash. Studies have also failed to confirm any consistent relationship between speed variations and crash likelihood.

In 1999, the New Zealand Midland police district hidden camera trial also failed to reduce fatalities and increased injuries despite reducing average speeds significantly. It is clear that in New Zealand since 2000 lower average speeds have failed to reduce fatalities compared with pre-existing trends and are now associated with sharply increased injuries.

I believe the rigid enforcement of speed limits has failed as an accident prevention measure for the following reasons:

Firstly, death and injury statistics trend differently and most likely depend on different factors/populations. Deaths are a very small subset of crashes and result often from very gross failures - falling asleep, intoxication, failure to slow at an intersection, head-on overtaking, falling off a hill or into a river. Most of these are unlikely to be sensitive to normal variations in speed.

Secondly, people prefer to travel at different speeds. Typically men driver faster than women yet have about the same rate of accidents or fewer per distance travelled. There are also marked variations between preferred speeds of drivers of different kinds of vehicles, drivers from different income categories and from different urban/rural environments.

I conclude that people are generally very good at judging their own risk and adjusting their driving to that. (I think research should focus on why they sometimes make errors.) Rigid enforcement of speed limits likely has the following detrimental effects:

a) Overtaking is much less efficient and less safe because it takes longer to pass slowly within the enforced speed limit and traffic bunches up behind slow vehicles.

b) Faster drivers become frustrated/impatient/bored/inattentive.

c) Slower drivers feel pressured to drive at the speed limit and are focussing on the vehicles behind instead of the road ahead.

d) All drivers try to make up time by maintaining the speed limit even on difficult curves/roadways/conditions because they cannot go faster on safe segments.

e) Drivers spend significant distraction time and focus watching their speed and looking for patrol cars and speed cameras.

The safest conditions may actually be relatively low speed limits enforced sensibly (ie only clearly dangerous/foolish infringements prosecuted). This would allow slow drivers to drive within the speed limit and within their own preferences without feeling additional pressure and would allow faster drivers to pass them in the most safe way.

Most of the traffic injury research suffers from the statistical "ecological fallacy" of assuming individual attributes can be deduced from average measurements. Just as drivers are not statistically 50% female/male, the average actually conceals quite different sub-populations which have different needs and forcing everyone to the average can be sub-optimal for almost everyone.

Whatever the reasons, it is clear that the "speed kills" policy has failed disastrously. Injuries and ACC costs are increasing. Continuing with failed policies is not an option.

The facts seem to be quite clear. Please advise whether ACC has any sound basis to defend their analysis as per my points 1-4 above. If not, the Government must act to remedy these alarming and costly injury trends. Please advise your intentions.

Yours sincerely

Alan Wilkinson

7 December 2004

Dear Mr Wilkinson

Thank you for your further email of 8 November 2004, regarding the rising motor vehicle injury trends since 2000. Whilst I applaud your enthusiastic research into these matters, ACC and I are not privy to the methodology with which you have gathered your information.  Therefore, you will appreciate that I cannot comment too specifically on these issues.

With regard to the rise of claims being registered, clearly you disagree with the point that I made about placing your statistics in context.  Since the introduction of the Injury Prevention, Rehabilitation and Compensation Act 2001, ACC have actively encouraged claimants and potential claimants to pursure their entitlement.  ACC's data shows there are sections of the community that do not access their legal entitlement to compensation and medical treatment services.

You have raised valid and interesting issues that challenge the whole school of thought surrounding the correlation between increased speed and injury statistics.  ACC considers the Land Transport Safety Authority (LTSA) the experts in this area and is guided by its research.  I am advised that the "World report on Road Traffic Injury Prevention" published by the World Health Organisation states "the speed of motor vehicles is at the core of the road injury problem", and goes on to say "speed influences both crash risk and consequences".  ACC will continue to align itself with the New Zealand Police and LTSA, to forward the injury prevention message.  ACC does not participate in the enforcement of the law, which I suggest is key to your concerns.

I will forward you letter to my colleague Hon Harry Duynhoven, Minister for Transport Safety who will be able to address your concerns appropriately.

Thank you again for your letter.

Yours sincerely

Hon Ruth Dyson


From: Alan Wilkinson
Sent: Friday, 10 December 2004 1:54 p.m.
Subject: Increasing traffic injuries

Hon Ruth Dyson
Minister for Accident Compensation Corporation

Copied to: Rt Hon Helen Clark, Prime Minister

Dear Ms Dyson

Thank you for your letter of 7 December 2004 regarding the sharply rising motor vehicle injury accident trends since 2000.

One can hardly take the WHO statement you quote seriously considering that motorways are unquestionably the safest roads, yet have the highest speed limits and actual speeds. Moreover, vague generalisations like that can carry no weight compared with specific facts such as the current New Zealand evidence.

You state that ACC regards LTSA as the experts and is guided by its research. You have referred the matter of enforcement of speed limits to the Minister of Transport Safety. Unfortunately, we can have no confidence in LTSA research competence or objectivity. They have persistently failed on both counts and without a wholesale replacement of management and staff will doubtless continue to do so. I note that the policy role on transport safety is being transferred from the LTSA to the Department of Transport which could have been encouraging had the Government not also stated that the same staff would also be transferred. Clearly nothing will change.

Regarding ACC responsibility, I would be happy if the ACC focusses sharply on its own business. It must fully understand its own data and actively identify and pursue adverse trends. It must also be open with the public and challenge programmes which it has evidence are failing.

Please advise what further analysis, research and public information campaigns ACC intends to undertake regarding the disastrous increasing motor vehicle injury accident trend.

Yours sincerely

Alan Wilkinson 


26 January 2005

Dear Alan

The Hon Ruth Dyson, Minister for ACC has passed on to me copies of your correspondence with her and asked that I provide a response.

You have received information from the Ministry of Transport, the Land Transport Safety Authority and the NZ Police through correspondence and responses to official information requests. There is nothing I can add, in terms of technical data, to what has been already provided.

You will no doubt be aware of the changes that have taken place in the transport sector as a result of the Transport Sector Review, which reported earlier this year. One of the key changes has been to ensure that road safety policy advice is located much closer to the centre at the Ministry of Transport. The new Safety and Security group in the Ministry now has clear responsibility for the provision of this advice.

I am very familiar with the concerns raised by you and others about the current approach to managing speed.  I have been working with the Ministry and other agencies with responsibilities for road safety and we are in the process of attempting to address these concerns with a mixture of new policy, some refocussing of existing policy and expediting some important initiatives that were already in train.  For example, work on speed zoning and on-road warning signs that will help drivers to stay within safe limits on the road.  As you will be aware the current 100km/h speed limit on the open road is a default limit and entirely inappropriate for much of our narrow and winding network.

The work we are doing on speed is being integrated with a third implementation package designed to achieve the Government's Road Safety to 2010 strategy.  I hope to be making some announcements about this shortly. 

Yours sincerely

Hon Harry Duynhoven
Minister For Transport Safety

This correspondence continues here.