Inactivity, cost-benefit analysis, risk compensation (more John Adams)

In my previous post I outlined a well-known argument about hypermobility presented by the geographer John Adams. He’s a very readable academic whose work has been in areas that interest me and when I first came across him I read through pretty much all of the
and letters available on his website.

Walking-and-cycling advocates will probably already know of Adams because he was the co-author (with Mayer Hillman and John Whitelegg) of one false move; a study of children’s independent mobility. This substantial bit of research is the origin of the figure that, in 1971 80 per cent of seven and eight year old children were allowed to go to school without adult supervision but by 1990, this figure had fallen to 9 per cent.

But he goes waaaayyy back beyond this. One of the earliest (1970) pieces in his archive discusses ‘london’s third airport’. Yes, this airport capacity business has been going on that long (I was only around eleven at the time but I remember that it was all over the newspapers). Adams produced a tongue-in-cheek suggestion that, never mind Foulness or Cublington, the ideal location – the right size and with links already in place – is Hyde Park. Parody is always a bit of a gamble – even prior to the internet. Adams’ reductio ad absurdam of planning priorities was written about in The Times and the newspaper then received and printed a genuine letter from a retired air-vice marshall which heartily applauded such a logical location for a London airport and pointed out that he himself had made the very same recommendation in 1946. Adams relates this in a later essay about cost benefit analysis which is worth reading because this kind of issue is very much still with us. (He takes another, shorter swing at COBA in the article Vogon economics and the hyperspatial bypass)

None of the above is particularly contentious to anyone of a vaguely green disposition, but when he gets on to road safety things start to heat up because he is a seatbelt sceptic. Now that just sounds like a bit of wilful and ridiculous contrarianism, but hang on because this is interesting.

To begin, let’s be clear about what exactly it is he’s doubting. If you are in a car crash, wearing a seatbelt will increase your chance of surviving. Nobody is sceptical of that – it is supported both by evidence and common sense. So if everything else remained equal – same behaviour, same number of accidents, same kind of accidents – then seatbelt legislation really would save lives. Adams is suggesting that everything else did not (and could not) remain equal; daft as it initially sounds, some safety interventions might increase the likelihood of accidents even as they decrease the severity of their consequences.

The argument has two strands. The first is that the aggregate evidence does not support the almost universal assertion that the introduction of compulsory seatbelts has ‘saved lives’. This is quite astonishing because this claim is frequently made, usually quantified and has itself become part of accepted common sense. This part of the Adams’ argument is fairly detailed and before dismissing it you should perhaps read the full account or a more recent and shorter version, because the statistics are persuasive. Broadly, seatbelt legislation was enacted in almost all countries against a background trend of already decreasing road accidents (see fig. one here).

Now I know what you’re thinking, and to be honest I’m feeling slightly embarrassed about the previous paragraph. I might easily be mistaken for one of those shouties who leave comments on blogs that go: “Evolution/Global warming/Environment. It’s all a scam !!! As proved by this long list of badly informed links!!!”. Or worse, a clever-clever contrarian who will present smart-arse arguments against decent things just for the intellectual fun of it. I’ve just waved my hands and said ‘read this’. There’s no reason you should do so. I mean, what do I know? Not very much I’m happy to admit, but a point to note is that Adams’ argument about seatbelt efficacy is not rocket science and only needs some basic experience of statistical thinking to follow. Anyway, let’s argue about this some other time shall we? If we just provisionally assume that Adams has made a case worth considering, how does he account for this?

The second strand of the argument concerns risk compensation. This is the idea that safety benefits have a tendency to be consumed as performance benefits. The full arguments runs:

  • We all have a preferred level of risk – life has uncertainties built in, some people tolerate or even enjoy a higher risk than others and all risks are taken because of a perceived benefit – even a tiny one such as the slightly greater convenience of crossing the road away from an offical pedestrian crossing.
  • Interventions which are intended to make certain activities safer, can sometimes change how we perceive the riskiness of that activity
  • In order to maintain our preferred level of risk we will change our beahviour – for example it feels safer to drive faster with a seatbelt.

Adams calls this the ‘risk thermostat’. There seems to be gradually accumulating experimental evidence in its faviour.

The overall effect of the seatbelt law, claims Adams, is not to reduce danger but to redistribute it:

“The evidence from Britain, which has been singled out as the only jurisdiction in the world in which it is possible to measure fatality changes directly attributable a seat belt law, suggests that the law produced no net saving of lives, but redistributed the burden of risk from those who were already the best protected inside vehicles to those who were the most vulnerable outside vehicles”

The downward trend in accidents which was already present in all countries before the enactment of a law is interesting for a second reason. Almost by definition, ‘developing’ countries came late to the motorization party, so that when their citizens started to acquire cars, the cars which they bought were advanced – developing countries didn’t have to start afresh with the model-T – and came with various technological safety features. So if it were a question of technology alone, these newcomers should start with an accident rate which is close to the already-developed countries. This doesn’t seem to happen, which suggests that there is an element of learning. To be exact, pedestrians and cyclists have to learn to keep out of the way.

“the long-term decrease in death rates .. is much more plausibly attributable to myriad behavioural adjustments in response to the increases in the threat of traffic”

That suggestion is by no means unique to John Adams, but it is a hard one to swallow. Over the years a great deal of effort and ingenuity have gone into safety devices, and it seems almost insulting to say that they haven’t worked as well as hoped. Not only that, but that ‘road safety’ has increased the amount of unfairness in the world. (And btw, if you’re still reeling at the thought of anyone being a seatbelt sceptic, I will stress that the argument is NOT that you personally will be safer without a seatbelt in a context in which everyone else wears one).

It is this type of argument that sits behind the way that some transport thinkers refer to ‘the road safety industry’. I agree that this seems a very shocking way to talk if you don’t know what lies behind it. It’s not that these people are cavalier about making the roads safer, and the term road danger reduction has been coined (by Robert Davis) to capture the idea that taming and reducing motor traffic is the way to do this. In contrast, ‘road safety’ regards motor traffic as a sort of force of nature that our public policy should accomodate and defer to.

Anyway, dear imaginary reader, make of this what you will, but I thought you might find it interesting because this is not the sort of thing you usually get to hear about – even on BBC4. I have a bit more to say about John Adams but I’ll leave that for the next post.


An essay about personal transport that I often recommend to people (but which they only occasionally read) is John Adam’s 1996 essay Can technology save us? (if you do open the link, don’t be deterred that the pdf appears to be 32 pages long – the article is only 16 pages).

It is worth reading the whole thing but in essence it presents an argument that it is possible to have too much of a good thing and in this case the good thing is personal mobility. Not the technology that gives us that mobility but the mobility itself. This idea seems not outrageous but simply unthinkable. Once one has managed to think it, then it seems outrageous – patronising, elitist, anti-progress and just self-evidently bad. Or at least the conclusion seems bad if you haven’t followed the arguments that lead to it. Here is the crux of it: a personal choice made by one ordinary person is negligible. Hurrah for choice, we’re all in favour. The very same choice made by many people is not negligible, yet in the case of transport, this is ignored. Adams argues that we were not (and are not) given the true choice. He puts this is the form of three imaginary opinion polls:

1. Would you like a car, unlimited air-miles, and all the computers and communications facilities presently enjoyed by Bill Gates?

” … at present most people in the world have never flown, and do not own cars or computers. Their answer to this question, everywhere in the world is overwhelmingly yes. In answering, most people probably imagine the world as it is now but with themselves having access to the enlarged range of opportunities that they see present car and computer owners enjoying […] politcians, technologists and transport and communication planners everywhere are encouraging people to believe that everyone’s wish can be granted”

2. Would you like to live in the sort of world you would get if everyone’s wish were granted?

For such an opinion poll to yield meaningful answers there would need to be agreement about what such a world would be like. It would probably be grossly polluted, noisy, congested and anxious about the security of its energy supplies. Let us assume, however … that technology will solve these problems. What else might we expect? [drawing on the previous discussion in this paper] we can can speculate about some of its main features:

  • It will be a polarized world. Not everyone’s wish can be granted. About a third of the world’s population will never be old enough or fit enough to drive … Their disadvantage will increase as [everyone else’s] car dependence increases. they will be second-class citizens, dependent fortheir mobility on the withered remains of public transport or the goodwill of car owners. [universal car ownership will never be possible]
  • The world will become one continuous suburb. The traditional city, built for people not cars, could not exist. The last unspoilt islands and wilderness areas – which travel writers incite us with a sense of urgency to visit before they are spoiled – will be spoiled …
  • Geographical communities in which people know their neighbours will be replaced by aspatial communities of interest. People with similar tastes, interests and life-styles will commune on the internet or meet at conferences and vacation resorts. More high-security enclaves of the wealthy will be developed, but because of the fragmenting force of their inhabitants mobility, they will not function as true communities […]
  • Travel opportunities will be destroyed. The cultural and linguistic diversity in the world – the experience of which provides the motivation for much travel – will be obliterated by the rising tide of tourism […]
  • Fragile ecosystems will be destroyed: wilderness retreats with access to it. The provision for parking and road space for more than ten times as many motor vehicles will require paving much more of the world […]
  • Street life will disappear. The spread out scale will defeat pedestrians, and traffic will make cycling too dangerous. There will be no local shops to walk to. […] A world full of traffic and strangers will require the constant supervision of children who will no longer be alllowed to play in the street. […]
  • Law enforcement will become Orwellian. A world full of highly mobile strangers will require ever more ingenious technology to detect and apprehend wrong doers. As travel becomes easier physically it will become more difficult bureaucratically. […]
  • […]The ease with which one can live one’s life in a community of interest will diminish the contact people have with their geographical neighbours. concern for the local environment and the welfare of one’s geographical neighbours will diminish as people sped more time in cyberspace
  • Political authority will become more remote […] As technology deluges us in information, it leaves us less time for contemplation and reflection, and forces us to employ ever cruder perceptual filters in order to make sense of it all […]
  • Democracy will disappear […] democracies, to function effectively, require common values, and a measure of agreement about societal goals forged out of common experience. If distance is vanquished the requisite minimum level of concensus and trust will be unattainable … “

And what of the third question? The one that we really ought to ask?

3. Would you like to live in a cleaner, quieter, more convivial world in which you know your neighbours, it is safe to walk and cycle, and children are allowed to play in the street?

Transport and communication planning is in the grip of of a linear, backward-looking vision which extrapolates past “progress” indefinitely into the future. The vision is being sold on a false prospectus that invites individuals to imagine the world as it is now but with themselves having acess to the enlarged range of opportunites currently enjoyed by a small elite – an impossible world in which everyone is richer and more mobile than average.

Transport and communications planners alone cannot, of course, create the world described in opinon poll 3. But they can create conditions which will make such a world impossible […]

He therefore argues for priority to be given to policies which:

give absolute priority to those forms of land use and modes of transport – walking, cycling and local bus services – that promote a human scale of living

Well. That seems an extreme dystopian view of everything. It simply cannot be right. I’m sure my selective quotation does not look convincing – clearly Adams has overlooked this, that and the other obvious thing, and of course it was written in 1996. However, I think it is worth reading the whole thing. When I read it myself I found his conclusions chilling.

Ultimately the argument comes to the conclusion that we simply have to travel less – and yet I see no possibility of this happening because I cannot see that there is any limit on our desire for mobility. Obviously, it is better to be able to get about, travel a bit. Obviously, it’s bad to be confined to your village or town all your life and never see the sea or visit a foreign country. And yet, if too much casual travel (and who decides what is “casual”?) is as problematic as Adams argues, where do we draw the line? And who draws it? There is no logical point at which increasing travel passes from “life-enhancing” to “life diminishing”. As with so many sustainability issues, we simply have to engage with this – yet it is almost certain that the more-powerful are going to try and hijack it as a way of maintaining their power.

So don’t expect a simple conclusion from me – this isn’t that sort of blog.


See the following other posts:

The problem

How much choice do we really have?

More about choice


The problem restated

Epidemic of sloth

I have mentioned previously that I reckon one of the most serious of the negative effects of motorized traffic is car-induced sloth.

There is a ton of evidence that physical activity is almost incredibly beneficial to health – if it were a drug you could swallow they would have put it in the water supply by now. “A ton of evidence”. Hmmm yes, that is a bit handwavy, I know. So, for my imaginary reader who is a naïf in the shouty world of transport policy:

* A bibliography of some actual proper journal papers

*A more lengthy (and chatty) compendium of evidence from Cycling England (and the very fact that the government created a quango to promote cycling tells you something about the amount of evidence)

If you care to google some suitable terms, you will find that there is more.


So yes, ok fine. Personally I’m prepared to take as given that moving about under my own muscle-power is good for me. I don’t have to chase up every single journal article – I’ll trust the published work of epidemiologists and medical statisticians and physiologists and whoever because I have no reason whatever to doubt that their knowledge is much more deeply grounded than mine in their areas of expertise. So physical activity is good for you, and it is very “dose responsive” – even a small amount is beneficial and you have to do a huge amount for it to be damaging.

I was thinking about this yesterday, while walking back home from Bristol City Museum, where I’d gone to buy a nice card for my mum in the museum shop (about half an hour each way). I wondered about the other side of the problem – how much physical activity are “we” actually doing?

I knew the recommended minimum levels – a total of two and a half hours a week of brisk walking or normal cycling plus a bit of muscle-type exercise. Two and a half hours walking? That’s really not a lot. A fifteen-minute-each-way commute to work would cover it – then dig the garden at the weekend and you could be smug. And anyway, the world seems to be chock-full of amateur athletes these days. Whole magazines devoted to triathlon and running and cycling and climbing and anything you can think of. Whole shops full of (frankly, rather sexy, cough) sports gear. Endless, endless, internet chat about the arcana of sports footwear. Everyone’s at it! I was suddenly overcome with doubt – surely there just couldn’t be a problem with levels of physical activity? Find some research.

First stop for this kind of question has to be the Office of National Statistics. From there I found the publication statistics on obesity, physical activity and diet 2013. The physical activity section relied heavily on some research from 2008, the health survey for England – 2008: physical activity and fitness.

Part of the survey involved a people wearing accelerometers while going about their daily lives so we have some objective measure of activity levels. The standout sentence in the summary report was:

Based on accelerometry, only 6%of men and 4%of women met the government’s current recommendations for physical activity, by achieving at least 30 minutes of moderate or vigorous activity on at least five days in the week of accelerometer wear, accumulated in bouts of at least 10 minutes

5% of the population manage to do what is, or should be, for an average person (and I’m sorry to have to put it this way, but really) the equivalent of a piddly bit of walking. It even counted if you did it in 10 minute bursts – the time it took me to walk to the bus or tube when I lived in London, the time it takes me to walk to the coach station in Bristol.

But wait, you think, maybe the survey included a disproportionate number of “old folk”. Well it was a proper large random sample, so the proportions would have matched those in the wider population, but just before I disappear in puff of flabbergastedness, let me add that, of course, as you would expect, the youngest age group did take a lot more exercise:

Men and women aged 16-34 were most likely to have met the recommendations (11% and 8%respectively),

I hardly know what to say. Yes, I knew that levels of activity were not as good as they should be, but it really hadn’t connected for me quite how bad things are … and yet there’s all that hoo-har about sport and fitness and going to the gym and doing marathons for charity … oh, we are such symbolic creatures aren’t we?

A quick word about carbon

I went to hear a talk by Kevin Anderson of the Tyndall Centre yesterday.

Now I’ve stated previously (and if you look at yesterdays post you’ll see I’m not the only one who thinks like this), that the carbon aspects of transport are a bit of a red herring when talking about active travel. There are so many other problems caused by too-many-motorised-vehicles and too much resistance to looking this in the face, that if you start dragging climate change into it, all you do is give people an excuse to fantasise about cars running on hydrogen electrolysed from water using fusion reactors. Dream on, as they say on t’internet, dreaming doesn’t require you to do anything.

This is not to say that AGW is not deadly serious so it does deserve a quick word and last nights talk is a good excuse.

Yes, less driving will be a part of reducing CO2e emissions. In a world which avoids two degrees of warming (now look who’s dreaming), you will find yourself, and your family, and your friends, and your workmates, walking or biking to work, or the shops, or school, or entertainment, because these will all be closer to where you live. It won’t feel odd or weird or unpleasant because everyone will do it.

Which brings us to Anderson’s talk, because his main thrust is that we are living in a fools paradise and la-la-lahing about how much things would have to change to make the reductions which will get us anywhere near a good probability of avoiding Two Degrees. It was good to hear it said out loud.

Every so often people produce quantitatively plausible scenarios for rapid decarbonisation (for example the Centre for Alternative Technology’s Zero Carbon Britain) so it could be done – but it really would involve throwing everything at it. Not “oooh we’ll have nuclear so we won’t need those horrid whirly things” – you need the nuclear AND wind. Not even “oooh well offshore wind is ok, so we don’t need onshore” – the really good offshore is slightly in the future, whereas good onshore is available NOW and we have to start NOW, so NOW we need both – oh and photovoltaics, and more research into wave, and carbon sequestration, and some biomass, and gas as an interim replacement for coal, and insulation, and woolly jumpers, and better building design, and behaviour change, and modal shift, and less traveling, and overhaul of land use, and dietary change, and and and. Throw Everything at it.

It’s not going to happen is it? Well it seems unlikely, and so perhaps I will say just a little bit more about the relation between personal choice and societal change. In a short while. Just don’t say I never mentioned a bigger picture.

Oh and incidentally, the Netherlands may have it right about cycling but they still have higher per capita GHG emissions than the UK (according to this graph from Renewable energy without the hot air).

The problem restated …

… rather nicely, I think, by Ian Walker

At the moment there is an incredible research effort to design better cars for the future. None of these efforts address the fundamental design flaws of the car. Even if somebody came up with a car that runs off angels’ sighs and never crashes, it would still encourage sprawling urban planning, bad land use (especially for parking) and would still encourage its owner to get fat and unhealthy. The population is rising; we don’t have the space to accommodate more and more cars and we have some serious population health issues. More cycling solves a swathe of problems at a stroke, and all it requires is a simple machine that most people already have lying around their home somewhere.

I wonder if this works?

I think these signs are probably quite expensive to implement, because this is the first one I’ve had a good look at. It informs drivers of their speed:

… and then tells them off if it’s above 35mph:

… and says thank you if they do:

Wonder how long the effect lasts? Has there been any research on this? (TRL perhaps?). Can’t imagine it’s that effective, but might be a bit useful.

Anyway, this example was on a road close to where I grew up. The very road in fact, that was sufficiently dangerous to ensure that I was not allowed a bike as a child. It doesn’t seem to have got any better, though there is a painted cycle lane along a random length of it. And I did spot one or two brave middle-aged blokes on heavy-looking mountain bikes. Outside the likes of Bristol and London that seems to be what it’s like.

Why behaviour?

You’ll see from the ‘table of contents’ to the right that I’m intending to write a fair bit about something called ‘behaviour’. Don’t run away with the wrong idea though. I’m not going to suggest that the transport woes of society can be solved by using cunning social psychology to persuade everybody to behave differently.

There is rather a lot of evidence that the direction of causality in social life is not as straightforward as we think. If more people walked and cycled then walking and cycling would become easier. If the built environment were designed better then more people would walk and cycle. If the cultural environment assumed that active travel was the default then more people would travel under their own muscle power. But if enough people decided to walk and cycle then the cultural environment would assume it was the default and a better built environment would be put in place. Oh. We’re back at the start – I thought you knew where you were going? Here is a diagram of this, helpfully provided throughout our towns and cities:

‘Society’ is just the aggregate of individuals making individual choices – what else can there be? Yet when an individual makes a choice, it is not, and cannot be, made on a neutral playing-field, it is made in a social context which contains many cultural and social pressures – some of them almost irresistible. Yet these are created by other individuals … so … what on earth can be done?

This type of system problem is pervasive in environmental discussion and there isn’t a simple answer to the question of “what can I do?”. Here is my current position on the matter.

It is officially recognized that cycling and walking are a Good Thing. But this recognition is patchy and half-hearted, the consequences have not been properly thought through. If there was real political will to favour walking and cycling (backed up by fuss-free public transport), then it could be done – as shown by the Netherlands. And yes, a big part of that is infrastructure. Infrastructure is the primary thing. It won’t work to hope that enough people will stop driving and start using their legs because we persuade them to do so – we cannot persuade enough people to make enough difference. Persuasion is too slow a process and the current road conditions militate too strongly against it. At present, Cycletopia is a nice place to visit but seriously now, you couldn’t possibly live there.

But it might work to persuade enough people to start making a fuss about walking and cycling that sufficient political will starts to develop – you’d need fewer people to get this one moving. So ‘spreading the word’ is not a waste of time. ‘Advocacy’ can take many forms, but for best results it really might be useful to know a bit of this social-sciencey-behavioural stuff – otherwise you could just end up preaching or asking for the wrong things.

And of course, even when the political will is there, it’s not only about the infrastructure, even though that has to be top priority. The way I think of this is that all the ‘soft’ stuff – the training, the persuasion, the information giving – is like the lubrication of a machine. The oil can do absolutely nothing in itself, yet is essential for things to work properly. And if a machine is completely seized up it might be able to get it working again. So another reason to pay attention and try to get it right.