How would you measure the safety of private motor vehicle travel?

Let’s agree to focus on fatalities. Serious injuries are also important, but all the points I am going to make hold equally as well for injuries as for fatalities. 

Probably the silliest way to measure road fatalities is per vehicle. Our current rate is 5.5 per 100,000 motor vehicles. This rate has been dropping steadily for decades (for instance it was 43 in 1980) not only because road safety has been improving (it has), but because there are more cars per person. In 1950, the whole nuclear family were killed in their FJ Holden. These days, Mum, Dad and the kids share two or even four cars and spread the same total fatality risk across these cars.

The most common measure is fatalities per head. The number of road fatalities per 100,000 people in Australia in 2012 was 6.1. By way of contrast, the suicide rate was 10.0 per 100,000. This measure is a little strange when one considers that it was way lower in 1914. Why was it lower in 1914? Are we really doing worse 100 years later? No, it is because hardly anyone travelled by private motor vehicle in 1914. They travelled by train or horse and buggy, which is way safer. All of which proves (to me at least) that the 6.1 per 100,000 figure is not a valid measure of the safety of road travel.

What we need is a measure which standardises fatalities by motor vehicle usage, and the most obvious measure of motor vehicle usage is kms travelled. This takes account of both the number of cars and of our increasing propensity to use them for short trips

Here is a question. How many fatalities are there (on average) per billion kilometres travelled? A billion kms is equivalent to travelling 25,000 times around the Earth. Stop reading now and think about your best guess.

You may not believe the answer. On average there are only five point seven fatalities per billion kms. How far would you need to drive to have an even money chance of dying? About 160 million kms. This is a little more than the distance from the Earth to the Sun. We are talking interplanetary distances here! Most people will not drive one million kms in their life time.

In 1975 the fatality rate per billion kms was 35.5 so the present rate of 5.7 is a drastic improvement. The chance of dying has reduced from almost no bloody chance to almost no bloody chance divided by 6. Driving a motor vehicle a short distance is just incredibly safe. If you only did it once we would really not worry about it. It’s just too small a risk to consider.

The problem is that you will not drive one km in your lifetime. You will probably drive half a million. So you take (and impose on others) a really, really, tiny, negligible risk many, many times. And even then, your overall risk of being involved in a fatality in your lifetime is low (around 1 in 300).

As a species, we are poor at assessing and responding to risk. Very small risks of terrible outcomes challenge our intuition and make us behave inconsistently. While we voluntarily subject ourselves to a chance of road death every single day, we simultaneously over-estimate the risk and support rather draconian penalties on individuals who increase their risk in specific ways.

I think that there is a lot of inconsistency in our attitudes to road trauma risk and the legal sanctions we impose to limit this risk. We seem to lack a coherent framework. Here are two principles that I think are hard to argue against.

The first principle is that the only sensible measure of the risk a person imposes on the community is their total risk of causing a fatality over their lifetime. (It is up to you if you want to include their own life in this or only the lives of others).

A reasonable reference figure for the total risk would be about 0.28%. This corresponds to the current rate of 1300 accidents per 23 million citizens multiplied by a 50 year driving career. We might express this as 28 per 10,000 people – just to make it a nicer number.

The second principle is that every citizen should be entitled to an equal allocation of this lifetime risk. Everyone gets a lifetime allocation of 28. If you don’t want to use it all, then more power to you. Some people will not even drive (though they will be driver around by others). But if you want a risk much more than 28 the state will start to sanction you.

Of course, we might want to reduce this allocation over time if community standards changed. And we might also include a maximum yearly limit of say 2. Anyway, for the sake of argument let’s take 28 as the lifetime figure.

I can also market my new framework with a catchy title: Vision 28. Road management authorities love this kind of thing…but more on this towards the end of the article.

If you accept the two principles behind Vision 28, and if you do not then you should think very carefully why, then the moral and legal landscape looks very different. Here is a personal example.

I drive around 12,000 kms per year. I actually take the train to work. Most of my 12,000 kms come from a single and completely discretionary source.

You see, I bought a holiday house last year around 75 kms from Melbourne. I go there probably 60 times per year – often just to work in an alternative environment to my office. The driving adds up to 9000 kms per year. So my unilateral decision to use a holiday house for pure pleasure has increased my yearly travel for 3000 to 12000 kms – and multiplied my road fatality risk by a factor of 4. To date, not a single person has chided me for the irresponsibility of this decision.

On the other hand, if I drive at 0.06 on one single occasion, I will perhaps double my risk on that trip alone. If it was a one off misjudgment, then my total yearly risk will be increased hardly at all. If I drive at this level 10% of the time (which would make me a social pariah) my yearly risk increases by 10%. This is equivalent to increasing my travel from 12000 to 13200 kms. Yet, if caught I am caught once at 0.06, I will lose my license and be popularly branded a bloody idiot.

Occasionally driving over the BAC limit does not have much effect on your total yearly or lifetime risk. This is simply not a matter of debate. It does not make you a bloody idiot at all. Driving like an idiot makes you an idiot.

You see there is probably no plausible driving behaviour that would quadruple my total risk short of driving pissed every single time I drive. But I have quadrupled my risk with the holiday house with nary a comment.

With Vision 28, managing risk becomes much more considered than blanket BAC and speed limits. Instead, limits can be tailored to circumstance and even individual drivers, and total kilometres driven can also be rationed.

If you think this is administratively impossible, you are probably correct right now. But in 25 years from now, all our cars will be GPS monitored and you will need to breathalyse yourself and insert your electronic license to start your engine.

The point is the state will know exactly who you are (your age and driving record), how intoxicated you are, what road you are driving on and how fast (and how far) you are going. We could calculate the risk for every km traveled. You could get a yearly running summary of you risk allocation usage – like you mobile phone usage indicator

If you really did not want a completely free system, the car could impose a personally tailored BAC and indeed speed limit. Drivers of the lowest age-specific risk with the best driving records would be cut more slack in speed and BAC limits than say younger drivers who had an accident in their first month.

And if you think it is outrageous to let some people drive faster and at higher BAC’s than others, we already have this system now. Older drivers can drive at a full 0.05 higher than P-plate drivers and 20km/h faster than learner drivers (though it is not usually expressed this way). If it makes sense to place extra limits on those with higher risk (the young), it is pretty hard to argue that it is wrong to place weaker limits on those with lower risk. In fact, it is oxymoronic to do so.

Those who have been in an accident could expect a revised assessment of their risk and consequently lower speed and BAC limits. Their lifetime risk up to that point could also be retrospectively recalcualted. Currently, you can have as many accidents as you like and you will probably face no serious legal sanctions. Your speed and BAC limits will be the same as mine. The worst consequence will be higher insurance premiums.

I would expect a pretty hysterical reaction from the current managers of road safety to such ideas. That is because they have been captured by a notion that you might not have heard of – Vision Zero.

The core principle of Vision zero is that ‘Life and health can never be exchanged for other benefits ..’ that ‘Human life and health are paramount and take priority over mobility and other objectives of the road traffic system.’ But these quotes are tame compared with

There can be no moral justification for the death of one single person.

Imagine what OHS would look like if this principle were generalised!

Rather than balancing the trade-off between public health (death and injury rates), public costs of improved infrastructure and individual driver convenience, it is recommended that the state spend whatever it takes and reduced speed and BAC limits to whatever it takes, to achieve a fatality rate of zero.

Where did this myopic approach that spurns any kind of cost benefit analysis originate? Sweden. Where else?

Every state road transport authority in Australia now pays lip service to this anti-numerate principle. No cost-benefit ratios for these heroic folks. The objective is zero fatalities – period. Yet, slower cars still spew out (probably more) pollution that increases lung cancer. That’s just fine. Death from bingeing on hamburgers is just fine too. So do they insist on spending infinite resources on medical research? No. Only deaths by road trauma are valued at infinity dollars.

Surprisingly (or not depending on you view of current culture), when I have mentioned this odious principle to people at barbeques most think it is OK.

What is wrong with it? It contradicts the free choice of every one reading this article who has ever driven. When you did so, you made a discretionary and voluntary decision to risk your very life for the pure convenience of getting point to point faster. You personally decided against zero risk. It is a unanimous decision. Most of you probably maximised your risk by driving at the limit too. Yet the Zeroists would impose their alternative vision upon you, regardless of the personal or public cost.

Now if society as a whole wants to target zero that is a rational (though unachievable) option. But we should at least be aware that we have spent all their lives up to now making a completely different free choice. And this free choice is consistent with Vision 28, not Vision zero.