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

How’s that national petition doing?

It stays open until mid April next year, but going from the graph below, it doesn’t look as if it will make the magical 100,000:

National petition start Aug

It did pretty well though and the 100,000 doesn’t necessarily matter – they sort of promise that any petititon that gets to that number will be debated in parliament but the get britain cycling report is going to be discussed on September 2nd anyway. There’s going to be another of those big cycling demos on the day.

Where am I?*

More politics. Our local Cycling Campaign recently organised the Bristol Cycling Summit.

I felt quite inspired by it. Amongst other things, words were said about “nettle grasping”. The chair of the meeting referred to the need for “corporate collective cojones – someone is going to have to take the pain”. The necessity for “sticks as well as carrots” was mentioned, together with the absence of an “easy way out”.

Good. It really does feel as if things are about to change – maybe they have already changed and this will only become clear with hindsight. Maybe. Unfortunately my “feeling” is not necessarily an accurate indicator of where we are. I might be feeling that maybe we’re on the cusp of taking a similar route to the Netherlands simply because I haven’t been around long enough. Although I have been broadly aware of the active-travel argument ever since I bought a copy of Richard’s Bicycle Book at the end of the seventies, I have only been involved in what is really the very shallowest of activism for a few years.

It has been argued on a number of blogs (if you’re reading this, then you’ve probably come across this) that the abstract argument has been largely won. Walking-and-cycling (despite the occasional elected noodlehead of the Hammond and Pickles variety) has been a policy “fluffy bunny” at least since the early nineties – perhaps even earlier. Fluffy bunnies are cute, everyone likes them, almost nobody is actually against them, but they are not, you know, a serious grown-up animal. So what we get is a cycle of Fine Words followed by inadequate funding combined with a failure to take any decisions which might actually do anything. It was a previous turn of this cycle that brought us all the dangerous and inadequate “cycling infrastructure” that is so striking the moment one gets on a bike. As that cycle went on, the timid infrastructure was neglected and forgotten (except by anyone who attempted to use it). Now a new round has started, active travel is in the limelight once more, fine words are being spoken, more people are riding bikes, things are looking good …

So where am I? Have I wandered in at the early part of the cycle, heard the fine words for the first time and naively been inspired by them? Or is it really different this time? Or perhaps not even “different this time”, because the cycle is more of a spiral – even the crap cycling facilities have pushed things forward a little bit, we’re not where we were back in the eighties when I was a regular London cyclist?

There isn’t a doubt that the amount of cycling in both London and Bristol has increased. But what about life outside the big trendy cities? I’ve extracted this graph from the figures in one of the many, many tables in the National Travel Survey for 2012. To be exact, it comes from table NTS0304 and represents not average number of ‘trips’ but journey ‘stages’ per person per year – so it catches the people who use a bike to get to the station and so on. I’ve included walking as a comparison.

NTS2012 walking_cycling

I think all one can really say about that is “hmmmmmm”. So I’ll cheer myself up by presenting just the cycling data (the data-scrupulous will notice that, as with the above graph, the scale on the x-axis is not completely consistent – but all it means is that the first bit of the line is “squashed up” and it doesn’t really do anything deceptive to the data presentation. I just didn’t feel like faffing around to correct this).

NTS2012 cycling

That doesn’t really make it much better, though there is, arguably – going through the ziggy bit of the line, which is what you’d expect with such low numbers anyway – perhaps, maybe, an upward trend from about 2003 onward (and I shall now remind myself about the nature of exponential growth – nothing seems to happen for ages and then, in a big whoosh, an enormous amount happens. Or you can have “tipping points” if you prefer. Anyway, I do sort of remain guardedly optimistic).


Completely off topic comment – nothing to do with transport whatsoever. If you haven’t already read it, Where Am I? is an entertaining (in the sense of ‘mind-twistingly strange’) philosophical story by Daniel Dennett)

Real politics, real communication ….

… are time-consuming and not terribly exciting. And although I’d much prefer to sit around and think, maybe read the odd journal article and look at some statistics (the latest national travel survey results were released recently), I have to admit that it is probably a better use of my time to stand on a bridge in the rush hour and hand out flyers to cyclists.
FTR bike placard

We were communicating the existence of the Bristol cycling manifesto petition. As explained previously the idea is to make visible the support for an improved cycling (and walking!) environment in the handsome-but-harrassed city of Bris. The support is necessary to stiffen the political will of the people with power (notably the mayor) to push things forward. The support does exist, but it is largely latent and so, boring as it is, and even with the internet and whatnot, talking to people’s actual physically present selves is still a necessary and excellent way to communicate.

Might active travel decrease obesity?

For reasons explained previously, I’m not really that keen on the whole blogging thing. Apart from anything else, almost everything one wants to say will eventually be said by someone else, so what’s the point?

Here is today’s example, it’s from Joe Dunckley, and concerns the connection between lack of physical actrivity and the “obesity crisis”. It’s from what, he warns us, is a rather sciencey and not terribly finished piece – and yes, it is slightly confusing to read unless you’ve already read a bit about the debate he references. Nonetheless it contains a point with which I am in total agreement. Joe’s post is aligned with a central thrust of psychobikeology: stop thinking about individuals (oh it’s so terrible the way people behave! Let’s talk to them about it!), start thinking about systems (people behave the way they do for complicated reasons, most of which are related to external circumstances. How might we change those circumstances?).

(The full post is here)

“[Garry Taubes commenting on the obesity crisis, in the journal Nature] is right to treat those who “blame individuals for not following [healthy eating] advice properly” with contempt. But not because the advice is wrong. Because any “advice” — right or wrong — is going to be useless. This is not a problem that individuals have created for themselves, and it’s not a problem that individuals can be “advised” to solve for themselves. This is a problem of the environment that we live in: the types of food that are available to us, and the opportunities for an active healthy lifestyle that have been taken away from us. […]

“[…] obesity, is a process of physiology. But it’s a problem of environment. […] you can’t solve a problem environment with advice alone. Bad lifestyle choices are not an individual failing. Good lifestyle choices need an infrastructure to support them.”

Just to expand a little here, strategically, I think it’s best to avoid claiming “answer to the obesity crisis” as one of the benefits of a public policy which takes walking and cycling seriously enough to do what is necessary (just as I think it’s strategically best to avoid banging on about carbon emissions too much). This is because it is a huge oversimplification – and therefore becomes a source of yet more contrarian ‘debate’ and dithering. I think it’s better to point out how great physical activity is in health terms (and how effortless it feels when that activity just happens as part of everyday getting around) and skirt around the whole psychological rabbit-hole of dieting-and-weight-loss.