Tag Archives: driver behaviour

In which I have to agree with the ABD

…that remedial lectures are not an appropriate alternative to prosecution for people who use mobile phones while driving. Stopped clocks, and all that. Rather less frequently than twice a day in the ABD’s case.

Lincolnshire, amongst others, are extending their remedial courses — the sort that are already widely offered as an alternative to prosecution for those caught driving too fast — to those caught using phones while driving. Greville Burgess, principal road safety coordinator for the Lincolnshire Road Safety Partnership, claims that such courses “could save lives”, but, this being a local newspaper, no evidence or source for the claim is cited. Burgess says:

“The evidence from other diversionary courses is very positive in that nationally less than 1 per cent re-offend within three years of completing the course. This strongly suggests that education rather than simple penalty points and a fine is more effective.”

But the latter does not follow from the former: Burgess does not give us the re-offending rates for those who take the penalty points. Is there really a statistically significant difference in rates at which people are caught — mark that, caught* — re-offending depending on which sentence they picked? But then, the utility of such numbers would be compromised anyway by the very fact that the offender picks the sentence: there is no randomisation in the groups we are comparing. The person who thinks that £60 and the points is the more lenient sentence might be very different to the sort of person who would rather spend £80 on the day-long remedial course. (Of course, both sentences look to me like absurdly light ways to deal with those who endanger the lives of others, but…)

This is the sort of intervention that is perfectly suited to a proper randomised controlled trial. While we’re at it, we could see whether combining the interventions — prosecution and remedial education — works better than either one on its own. If education really does work so well, why not make it a compulsory addition rather than an optional alternative to prosecution?

I don’t know what evidence Burgess thinks he has for his claim that these courses save lives, or are better than the alternatives, and I can’t find any likely candidates in the literature. But there is plenty of research on the topic, and a review of all the best evidence we have on driver education programmes — 32 properly randomised and controlled trials of advanced and remedial driver education programmes.  They found that the courses entirely failed to prevent re-offending.

And so far as I know, nobody has ever thought to investigate whether there might be side-effects to these policies. We have a prime-minister who sees moral hazard everywhere he looks, and is worried about whether we have sufficient deterrents to crime. We should not limit our assessment of driver education programmes merely to the rate of re-offending amongst participants. We must look at the wider and less immediately obvious effects of classifying mobile phone use while driving as the type of activity that merely merits spending a day getting a good talking to from a retired policeman. Perhaps there are no such side-effects. We don’t know until we look.

But I almost forgot. The prime-minister is also keen on some offenders being allowed their second chance.

I fear that this is now the second time I have found myself siding with the Association of British Drivers. But if I were to write about them every time they said something totally batshit crazy, I’d never get a moment’s rest.

* my own entirely unscientific observation is that, despite being universally recognised as extremely moronic behaviour, mobile phone use while driving is very common. The capture rate must be pretty embarrassing. I fear the 1% re-offending rate says far more about the efficacy of the policing than the efficacy of any remedies.

Can drivers be taught a lesson?

M’coblogger Ed thinks there is a case for teaching drivers to behave — specifically by appeals to patriotism. Education programmes are a popular idea amongst cyclists, cash-strapped councils, and road safety types. I dismissed them as a solution that doesn’t work in my own post on revenge and road danger, but didn’t go into any detail. So I thought I better ask: what’s the best evidence we have about driver education programmes?

Remember what I said about bicycle helmets. It may be common sense that teaching drivers will make roads safer and nicer places to be, but common sense is frequently wrong, and cures can kill if they’re based on common sense rather than evidence. Trying to educate drivers could make the roads safer and nicer. It could be entirely ineffective. Or it could make them more dangerous and less pleasant. Until we conduct a controlled trial, we don’t know which.

There are two systematic reviews from the Cochrane Collaboration looking at the effectiveness of driver education programmes.  Cochrane reviews are, remember, the independent synthesis of everything that we know about a particular intervention, and are considered by doctors to be the closest thing we can ever get to fact.

The first Cochrane Review looks at the effectiveness of driver education in existing drivers. The schemes that have been trialled particularly focus on advanced driver training — the sort of programme that is designed to improve hazard detection and reduce error making, and which is frequently recommended for professional drivers — and on the remedial programmes that are increasingly offered to drivers who break the rules as an alternative to a driving ban.  These are lessons and lectures rather than marketing campaigns, but the remedial programmes — lectures on why speed limits matter — are particularly relevant to the “be nice” approach to making our streets nicer places where people feel able to ride bicycles.

The review found 24 trials from 1962 to 2002, all in the US except for one in Sweden, with more than 300,000 participants between them.  With those sorts of numbers, there is little chance of the review accidentally getting a false result.  Four were for advanced driving courses, the rest for remedial classes.  The programmes ranged from the simple supply of written material (9 trials) — a letter and copy of the rule book — through group lectures (16 trials) to proper one-on-one classes (7 trials), but all were designed to improve “driver performance and safety”.

The trials typically checked up on participants two years later and compared the rate of rule breaking and/or the rate of crashes in those who received the education programme and the controls who did not.  There was no difference. The education programmes didn’t stop drivers breaking the law or having crashes.  The authors concluded that companies shouldn’t bother with driving courses for their staff, but should let them take the train instead.

The evidence reviewed isn’t perfect. They could not, for example, blind participants as to whether they were in the study or control group. And the conclusions apply to the 32 specific advance driving courses and remedial classes that were trialled — we can not say for sure that other types of education campaign wouldn’t work. But the evidence tells us to at least be very wary of investing in any campaign strategy that relies on teaching people to play nice.

The second Cochrane review looks at the effectiveness of educating school kids before they start driving.  These are the sort of programmes that are supposed to address the fact that 17-21 year old drivers are twice as likely to crash as the average driver. They are particularly popular with the Road Safety industry and there are several varieties common in this country.  Indeed, I have first hand experience: it must have been during the final GCSE year, aged 15 or 16, that we were all taken to the Bovington tank training circuit to take it in turns driving hatchbacks (sadly no tanks) around the track, doing hill starts, three point turns, reverse parking, and, as a treat afterwards, emergency stops from 70mph. While not everybody is privileged enough to get real practical lessons, the government does at least make sure that kids are taught how to get a learner’s license and find an instructor, what tests they will need to take, and are given a few road safety messages.¹ *

The Cochrane review found three RCTs with a total of around 18,000 students. The review looked at the public health outcome of the trials, typically measured as the rate of crashes and/or violations in the first few years of holding a license. Giving school kids driving education did not reduce the incidence of crashes and violations.

Indeed, the authors, against common sense, found evidence of the opposite. The reason can be found in the other outcome that the trials measured: the time it took the kids from turning 17 (or whatever age was relevant in their particular locality) to passing their driving test (which the study gives the awful name “license delay”). Kids who were given driving classes at school were more likely to seek and obtain a license, and they did so earlier — and we already know that age correlates with crash rate and rule breaking (or at the very least, being caught and punished for rule breaking).  Driving classes in school weren’t making people drive safely, but they were making people drive.

You can see why driver education programmes are so popular with the road safety industry, puppet of the motoring lobby. The trials reviewed by Cochrane were all from the mid 1980s, yet we continue to put money and effort into programmes that are worse than useless. My own school driving lesson was fifteen years after school driving lessons were shown to be harmful to our health.

Whenever questioned, the government cites as justification its own non-controlled study which showed that kids are able to recall and are vaguely more likely to agree with specific road safety messages when asked three months after the lessons. No, really. That’s it.¹

So drivers can be taught. They can be taught, before they even become drivers, that driving is normal, just something that everybody does. The moment I turned 17 I wasted about a hundred quid on driving lessons before I stopped to ask myself why. Everybody was doing it, right? You do GCSEs at 16, driving at 17, ‘A’-levels at 18. That’s how it works.

Perhaps they can be taught to behave and we just haven’t worked out how yet. There are not, so far as I am aware, any trials on the effectiveness of making motorists try cycling on the roads. But I suspect even that would have limited effect, and maybe even that could backfire too.

Because people generally don’t do what they’re told to do, they do whatever looks normal and natural and easy. You can call that selfish and lazy if you like, but I don’t think that will help you understand or overcome the behaviour. In the UK it is normal and natural and easy to learn to drive and then drive badly. And people refuse to be taught that the things which are normal and natural and easy, the things that everybody around them is doing, are wrong. Experience trumps the word of others.

In the Netherlands, incidentally, cycling is normal and natural and, thanks to the infrastructure, easy. In the UK it’s none of those things. Make it easy and you’re nine tenths of the way to making it normal and natural.

Continue reading


I’ve been meaning to write a bit more about the M4 bus lane, but haven’t had the time, so here’s a rather crude brain dump while I sit in the dark on a bus somewhere on the A9 in the snowy Cairngorms.

The Dutch infrastructure minister recently announced that speed limits on some stretches of motorway would be raised.  This would not help Motorists get to their destinations any quicker, she noted, but it was a change worth making because it would make the motorists feel better.  Aside from being a delightfully refreshing piece of honesty from a politician, it highlights again that behaviour and psychology should not be ignored when designing transport policy.  Philip Hammond should have been this honest when abolishing the M4 bus lane — instead of the weak nonsense about improving journey times, just tell the truth that it’s a cheap way of making Motorists feel better.

The M4 bus lane was designed to cut the journey times of Motorists entering London — to make their journeys faster and more reliable, and thus to cut the <insert absurd made up number here> billions of pounds that the Institute of Directors like to claim is lost because of their Jags being caught in congestion their supply chain being delayed by congestion.  The Motorist probably thinks that he too would like his journeys to be faster and more reliable.  But this is not quite true.  The Motorist would like his journeys to seem faster and more reliable.

The M4 bus lane was hated not because it increased car journey times or made journeys less reliable.  It didn’t.  As previously explained, the bus lane was a clever hack to the layout of a road with a bottleneck.  It made a tiny and irrelevant cut to journey times, while cutting lane changing and accident rates and thus greatly improving consistency in journey times.  The bus lane was hated because motorists thought it increased their journey times.

Part of it was the problem of common sense.  The likes of Jeremy Clarkson and Terry Wogan despise those scientists and academics with all their fancy facts and data — the problem with these researchers is that they don’t have any common sense, and common sense tells Clarkson and Wogan that taking away one lane of the M4 must have caused traffic jams.  No amount of your facts can change that.

Another part of it was recall bias: all of those massive pre-bus lane jams begin to blur into the distance, whereas this jam that I’m sat in right now is real — and hey look, there’s a bus lane.  Coincidence?

But it was more than this.  It was about people’s perception, and particularly people’s perception of queues.  Since I’m on a bus with no reference material and limited battery life, I’ll put it in bullet points:

When sat on a Motorway in a traffic jam, Motorists usually believe that their own lane is going the slowest.  It’s simple: when their own lane is moving freely, they’re concentrating on driving, and don’t notice that the other lanes are stationary; when their lane is stationary, they have nothing better to do than stare at all the vehicles which are moving freely in the other lanes.  So even if over time all lanes even out, the Motorist perceives that the other lanes are moving better — especially if the jam is severe enough that they spend more time stationary (observing others moving) than moving themselves.   (Hence all the futile changing of lanes in jams, which just makes the jams worse.)  This is the same reason why in the Post Office — wait, do blog readers even still use those?  OK, this is the same reason why in the ticket office at a major station, you have a single queue serving several windows, rather than independent queues.  Independent queues make people nervous about their decisions.

This perception leads to Motorists overestimating their time sat in traffic, and it’s made worse when they can see moving traffic — if the opposite carriageway is moving freely, or there’s a parallel un-jammed road, then the sight of moving cars merely serves to remind the poor stationary Motorist of their own lack of motion.  Drivers asked to estimate how long they were stuck in traffic consistently over-estimate the jam if they see other traffic moving freely.

So the M4 bus lane was about the worst thing you could do if you wanted Motorists to perceive that they were spending less time in queues.  Now when they were sat in a queue they weren’t just sat there with nothing better to do than get paranoid over the relative speed of the two lanes of traffic: they could also sit there watching the buses and taxis and prime-ministers go past at speed, constantly highlighting the fact that the Motorist was going nowhere.

The research shows this — have drivers estimate their queuing time with and without visible moving traffic nearby; or compare the driver and passenger experience of a stop-start motorway jam. It’s just another of the many fascinating little quirks of psychology — one of the bizarre things our brains do when confronted with absurd man-made situations like traffic jams.  You can make Motorists happily spend more time sat in traffic jams, simply by making them sincerely believe that it is less time.

(Somewhen I’ll try to find some interesting references, but 3G has just dropped out…)

Engineering, psychology, and a bus on stilts

This week I’m trying to clear up the loose ends of threads I began and never finished, and get rid of some of the draft posts that I started but never polished…

Last week I posted about tracked hovercraft and straddling buses — a tongue-in-cheek look at how through the ages engineers have proposed ever more overcomplicated engineering solutions in an attempt to manage our out-of-control transport problems.  I assumed that my learned readers would get the point without labour.  WordPress.com very kindly picked it as one of their daily front-page features, though, which led to it receiving around 4,000 spam comments, including several dozen along the lines of “wow that bus looks awsum and wood solve all our problems make one for america!!!?! (p.s. here’s a link to my blog!!!11!)”.*

Well, actually my guess is that the straddling bus will be just another absurd transport solution that fails to achieve the things that it is designed to achieve.  The stated purpose of the bus is not to get cars out of its way, it is to get the bus out of cars’ way: the designers complain that the frequent stop-starting of buses means that they hold up the traffic behind.  It will probably fail to achieve much in the way of making car drivers’ lives easier because the designers are obsessed with engineering and don’t consider Motorist behaviour.

Here are a couple of random fascinating psychology factoids.  I wonder to what extent the bus backers have considered them in their models?

  • When you make road lanes just a little but wider — as you will surely need to do if you are to accommodate the bus safely — people drive faster.  They’re not doing it deliberately or rationally, perhaps not even consciously, they just do it.  It feels right.
  • Drivers slow down for tunnels, and things that feel like tunnels — tree-lined avenues and close high walls.  Even if there’s nothing telling them to, and no rational safety reason to do so.  They just do it.

The cause of traffic jams is traffic.  Too much of if, behaving erratically.  We like to pretend that it’s bad engineering, because we can always fix engineering by replacing it with some different engineering.  And we like to pretend that it’s not the volume of traffic and the behaviour of drivers, because acknowledging this would mean giving up hope that one day the traffic jams will magically be solved.  But that’s the way it is: too many cars, too badly driven.  The straddling bus will probably not help congestion — at least, no more than a conventional bus on a conventional bus lane — because it will change driver behaviour in a way we can’t easily predict, but which (as described) will likely involve them slowing down and speeding up in chaotic waves as the bus passes them and they pass the bus.  It doesn’t sound like much, but these effects have a habit of amplifying themselves: the traffic between lanes will cease to be smooth, so cars will be changing lanes more, and this lane-changing contributes further to slowing things down, and also greatly raises the risks of accidents occurring.

Perhaps that effect will be marginal given all of the other existing complications and currents in the traffic flow.  Perhaps we’ll see other interesting unforeseen behaviour changes in the Shenzhen trial.  All that we can say for sure that everybody will be predictably surprised when drivers don’t behave in a simple rational manner.  Just like they were the last ten thousand times the solution to congestion was discovered.

The main reason the bus will fail, though, is the same reason that all urban roadspace provision schemes fail: create a new space for cars to drive in, and an equal or greater quantity of car journeys will be created to fill that space.  The cause of traffic jams is too much traffic.  Double the capacity for traffic and all you’re doing is doubling the size of the traffic jams.

Put a conventional bus on a conventional (parking and taxi enforced) bus lane.  It’s easier.

* Not that I’m not grateful for all your valuable contributions to our discussions ;)

The driving test in China

Melinda Liu in Newsweek, on sitting the written exam for a Chinese driving license:

The most memorable question is the one about intestines. Specifically, it’s a multiple-choice question about what to do if you come across a traffic accident victim with an open abdominal wound from which the small intestine is protruding. The choices are a) put it back, b) no treatment, or c) not put it back but cover with a bowl or jar, and bind the bowl or jar with a cloth belt.


To be sure, the official booklet of rules and regulations does have a chapter titled “Driving With Civility and Professional Ethics.”  One question asks if drivers should a) deliberately underestimate each other, b) compete for road supremacy or c) learn and help each other, adopt one’s strong point while overcoming one’s weak point and keep safely driving. No, I don’t know what the last homily means either.

The answers can be found in the article, alongside many other curious observations.

How many people die on China’s roads, and why?

These are not easy questions to answer.  The stats are difficult to find because the country and its bureaucracy is vast and dispersed; and because after collecting the data in painful detail, the authorities just publish whatever numbers they want you to see — even if that means making them up.  And they’re difficult to find because the primary sources are written not only in a different language, but in a whole different alphabet; and most importantly of all, they’re difficult to find because there’s a bug in the new Google results page that prevents it loading beyond the first page in FireFox on Ubuntu.  (I take my research seriously, guys!)

Lots of sources say that a quarter of a million people die in RTAs in China every year, attributing it vaguely to the World Health Organisation.  WolframAlpha also stated this number, attributing it only to “2002”.  So, eight years ago — when the boom in China’s car dependency was only just beginning — there were 250,000 road deaths in China, accounting for 19.2 deaths per 100k.  By comparison, the UK had just 3,864 road deaths — but, due to the difference in demographics, had a statistically indistinguishable 19.1 deaths per 100k.

The interesting thing to note, though, is that while China had more than an order of magnitude more people than the UK, it had only 3.5 million cars, compared to the UK’s 28.5 million cars.*  So while in the UK there were about 135 road deaths per million cars; in China there were a whopping 71,400.  In 2002 there were five hundred times as many fatalities per-car in China compared to the UK.  As Melinda Liu puts it, China’s 1.3 billion people own 2 percent of the world’s vehicles but account for 15 percent of global traffic deaths.

There are many hypotheses for why China’s roads are so anarchic and dangerous.  In reality, most of them are probably parts of the explanation, to varying extents.  One obvious reason is that most drivers in Beijing are new to the whole driving thing.  This is a city where car ownership is growing at 10% per year and half of all drivers received their license within the past 5 years.  Everyone is a new driver, and there’s nobody with experience to set an example.

Amateur sociologists propose all sorts of other reasons, focusing on the context of China as a non-democratic nation — why in an authoritarian regime is there this pocket of anarchy?  In Tom Vanderbilt‘s Traffic, Beijing-based journalist Jonathan Landreth proposes that a car in traffic is the only place where the established societal hierarchy of the city breaks down, to be replaced with another where the little guy can achieve equality with the company director or city official: everybody is trying to assert themselves and create for themselves an elevated status.  They’re overcompensating for something.  Drivers overcompensating? It all seems a bit implausible.

Meanwhile, in Newsweek, Melinda Liu says:

“What makes driving in China especially hazardous is a combination of corrupt officials who can be bribed into dispensing licenses to unqualified drivers, aging or rickety vehicles, badly marked road construction, inexperienced drivers, and truckers on long hauls nodding off to sleep as they transport yet more goods to feed the country’s booming economy.”

And Liu Shinan of China Daily suggests that it is instead about history: “After the cultural revolution, which lasted for ten years, it was a chaotic society.  People didn’t show any respect for the law, because Chairman Mao encouraged the people to revolt, to question authority.”  In Traffic, Vanderbilt traces this anti-authoritarian streak even further back, to Confucian ideas of personal rights and indifference toward the public good.  China has dangerous roads because Motorists don’t care for others.  But does that alone explain it?  Bai Ping suggests that it’s down to government officials setting a bad example by ignoring the law themselves:

As a matter of fact, China has very detailed traffic rules that are covered in computerized tests for license applicants. For example, motorists pay a fine of 200 yuan ($29.3) and lose two points if they tailgate or take a phone call while driving.  But there is less of an incentive for obeying the law if people realize that those in power are not following the law. When stuck in a traffic jam, who doesn’t want to go follow an official who veers off to drive on the road shoulder or a bike lane?

The main reason, though, is the most obvious one of all.  When the law is not enforced, people break it.

* All figures from Professor Google — these were thrown together in a lunch break, they are not serious scholarship or investigative journalism.