Traffic
Posted on Wednesday, March 4, 2009
Traffic Tom Vanderbilt Allen Lane 2008
‘The road, more than simply a system of regulations and designs, is a place where many millions of us, with only loose parameters for how to behave, are thrown together daily in a kind of massive petri dish in which all kinds of uncharted, little-understood dynamics are at work. There is no other place where so many people from different walks of life – different ages, races, classes, religions, genders, political preferences, lifestyle choices, levels of psychological stability – mingle so freely.’(p.6)
I’ve written a personal take on this book in my articles section. This review is a summary of its themes, and I hope will encourage more people to read it.
I learned a lot from Traffic, like the fact that traffic has been a problem for thousands of years. In ancient Rome, for example, carts were only allowed into the city at night to relieve congestion, but then kept everyone awake with the noise. There were complaints about speeding in medieval England. 1879 saw 5 hours of gridlock in New York. I like the way Vanderbilt draws on physics, mathematics, biology, sociology and psychology to explore different facets of traffic, from the pulsing of traffic jams to ant motorways to what’s really going on in the heads of drivers – and why driving and using a mobile phone is such a problem. It ranges round the world, giving us a front seat, and alarming, view of driving in Mumbai, London, Beijing and Los Angeles, among other places.
Driving is more complicated and skilled than we realise, Vanderbilt points out. He reports on how difficult it is to teach robots to drive in urban traffic, when there are countless situations to assess and choices to make: is that car parked or the back of a stationary queue? Who goes first when several cars arrive at a roundabout at the same time? How do you tell if a pedestrian is about to walk out in front of you? Drivers must cope both with the traffic laws of the particular country they’re in, and the unwritten rules and customs. For example, in the UK, most motorists routinely break the law by exceeding 70 mph on motorways, yet they’ll stop at a red light even if they can see it’s completely clear to proceed.
The counter-intuitive idea that removing signage in urban areas improves safety has been reported widely now, but it’s still interesting to read Vanderbilt’s description of it in action in various places. It helps persuade drivers that the road is not their space, specially where it goes through a village or community. In the UK, the speed limit sign is often the only thing which marks the fact that you’re driving through a village. The road itself still looks like the same highway rolling ahead of you.
A lot of driver behaviour is motivated by a sense of fairness. People should obey the rules, and not get an advantage over us. Vanderbilt discusses this in the context of merging for roadworks, where those who merge early get very angry with those who merge late, even though the quickest way for all traffic to get through is to use both lanes up to the point of merger, and then to merge in turn. Studies of queuing (yes, there are such things!) show that people prefer a single line to multiple ones even if having multiple ones is quicker, because it’s stressful seeing others get served/there before you when they came later. There’s an interesting discussion of why the other lane in a traffic jam always seems to move quicker. Apparently, though a car has as many passing events as overtaking events in congested traffic, that car will spend more time being passed by cars than passing them. Queues are like accordions, which stretch and compress. When you’re in the compressed one for several minutes, many cars sail past. When you’re in the stretched lane, it doesn’t take much time for you to pass them, and we aren’t so aware of the cars we’re passing, because we’re making good progress.
'You’re not stuck in a traffic jam. You are the traffic jam.’ German advert
Instances of road rage (or ‘traffic tantrums’, as Vanderbilt calls them) hit the headlines, but ‘normal’ drivers often show a lot of aggression too. They honk or make rude gestures or swear or shout when another driver makes a mistake. Pedestrians shout at speeding cars, drivers honk at oblivious pedestrians, cyclists annoy drivers and pedestrians, and also get threatened by them. The question, Vanderbilt says, is not why some drivers are homicidal maniacs but ‘why we all act differently.’ In traffic, he says, ‘we struggle to stay human.’ (21) This is partly because being in a car makes us mute. We can’t hear, or read facial expressions easily, or communicate. Human beings aren’t designed to move faster than 20 mph, we can’t make eye contact at that speed, or it’s not safe to look. Are we being honked because we’ve done something wrong, or as a thank you, or because our petrol cap is open? We quickly interpret other drivers’ mistakes as rude or hostile or totally incompetent, and draw on stereotypes to judge them: SUV driver! Women! Yet we don’t judge ourselves for doing the same thing.
Being a driver we are generally anonymous, stuck behind other drivers. So perhaps, Vanderbilt says, getting angry and sounding off helps us feel a sense of identity. Passengers don’t have the same issues, and solo drivers – unless in open-tops - are more aggressive. Vanderbilt compares this to behaviour online: ‘Being in traffic is like being in an online chat room under a pseudonym. … the normal constraints of life are left behind.’(p.27) Psychologists speak of the ‘online disinhibition effect’, where the ‘individual swells with exaggerated self-importance.’ Whether online or on the road, there is no consequences for being rude or harsh. You can ‘flame’ someone and sign off.
There’s a perception that we can talk on the phone and drive perfectly well. A driver on the phone may lower their speed and drop back. Their eyes may stay on the road once they’ve established the call, and they feel in control of their car. Except that even if their eyes are on the road, their mind isn’t. When we try and do two things at once, the quality of both tasks drops, yet we don’t realise how distracted we are. People may be able to cope with standard driving in this mode, but they can’t deal with the unexpected. The largest analysis of driving to date, says Vanderbilt, showed that nearly 80% of crashes and 65% of near crashes involved drivers not paying attention to traffic for up to 3 seconds before the event. A 2-second look away is enough for them to start to lose track, yet drivers drive as if world will not have changed when they look back, as if it was ‘live pause’ on the TV. But we only need to take that 2-second glance away at the wrong time for a crash to happen. Dialling or texting from a phone is clearly risky, but so is anything which takes our eyes and mind off the road, even lots of short glances.
One problem is that we don’t get feedback on our driving. When negative feedback comes our way on the road, we explain it away or quickly forget it. A speeding ticket is because police have to make a quota, a driver honking is them being aggressive, our passenger flinching or pressing imaginary brakes is about their nerves, a crash is bad luck. Other drivers are bad or incompetent and need their behaviour controlled through strict laws, but if the law catches us, it’s unfair, and why don’t the police go after the real criminals? In fact, we may be driving riskily and badly - using a phone, tailgating, speeding, not wearing a seat-belt. But every day we drive without incident, every journey that nothing bad happens, we’re reinforced in our belief that we are driving well. If we do have a near miss, it doesn’t necessarily teach us to drive more safely, it just confirms that we have the skill to get out of trouble.
When people do get feedback, though, it can be something of a surprise. Vanderbilt describes the use of DriveCam. A camera in the car is triggered by braking or sudden turns, and captures the driving behaviour which leads to near misses. It’s related to the thinking of H W Heinrich, an insurance investigator whose 1931 book suggested that in industrial accidents, for every 1 fatality or major injuriy in the workplace, there were 29 injuries and 300 near-miss incidents without injury. He argued that to avoid the one event at top of triangle, industries should tackle the many small events. While his theories are controversial, Vanderbilt acknowledges, the idea that near misses are scaleable to more serious incidents remains powerful for traffic, given how often human factors are responsible. One big study found that for every 120 incidents, there were 11 minor injury crashes and 1 serious crash.
DriveCam shows how often drivers are indulging in unsafe, careless behaviours - hands off the wheel, falling asleep, drifting in lane. Mostly, luckily, they get away with it. For example, there’s the van driver using his phone whose camera is triggered when his van drifts off the road. He saves himself, but 12 feet away there are children on the pavement. The driver is reinforced in his belief that he’s a good driver because he didn’t crash, yet it was only luck which stopped him hitting the children. If he had done, he might have said it was sheer bad luck that they were in the wrong place at the wrong time. Yet this would have been a perfectly avoidable crash if he’d kept his mind on the road.
One of the things which goes when drivers are on the phone or doing other things as they drive, is awareness of the wider environment. Vanderbilt refers to the moonwalking gorilla experiment,1 where people told to focus on how many passes a basketball team makes don’t spot the gorilla moonwalking through the scene. When we’re concentrating on one thing, we miss others. We’re limited in how much we can pay attention to. ‘Looked but did not see’ accidents are common, specially with motorbikes.
Indeed our perceptions as drivers aren’t terribly reliable. Particularly as cars get quieter and radios etc get louder, it’s hard to know what speed we’re doing. A flashing speed sign causes drivers to slow down because they haven’t realised how fast they were going, or that there was a speed limit, or both. We don’t always estimate other cars’ speed accurately, either. Because of the way our brains are wired, we think a small car is further away than a large truck, or assume a large object is going more slowly than a small one. For example, a jumbo jet seems very slow as it takes off compared to a small plane.
There is an interesting section in the book discussing the relationship between traffic fatalities and the economy as represented in a nation’s Gross Domestic Product. Though a low GDP means less wealth, fewer cars and low fatalities, it isn’t a straightforward link. In fact, research suggests that traffic danger is more closely aligned with corruption. If the legal authorities aren’t seen as legitimate, or the laws seem unreasonable, people are less likely to obey. While there’s a difference in traffic danger between countries which have a similar GDP – eg Belgium has twice as many traffic fatalities as the Netherlands – there is a correlation with corruption as measured on the Transparency International data. Countries with low corruption - Sweden, New Zealand, Singapore, Norway, Finland - are the safest places in which to drive. France has improved its safety as it has tackled its culture of traffic ticket fixing. I don’t know enough to evaluate this research, but it raises the interesting point that: ‘If GDP and traffic fatalities are somewhat related, and GDP and corruption are somewhat related, and traffic fatalities and corruption seem to be the most clearly related, then fighting corruption may be the best way to lower traffic fatalities and raise GDP.’(p.242)
To generalise a number of points from the book: driving is not something we do independently of other people. Perhaps we can handle a car well at speed, but we share the road with new drivers, lost drivers, distracted drivers, young or vulnerable pedestrians. What’s best for me in traffic – nipping down the rat run and saving time on my journey - may not be best for the common good: the noise for residents of that street, the cost of repairing a road not built for much traffic. If I tailgate or weave lanes on the motorway, I can send pulse waves further down the traffic queue which create a jam. For all the complaints about the unfair costs on the poor motorist, drivers don’t pay much at all towards the real cost of road maintenance, congestion, pollution, or the cost to the economy (let alone the human consequences) of crashes, fatalities, delays.
Yet, paradoxically, safety features can make drivers drive worse. Vanderbilt contrasts driving over a narrow mountain track with sheer edges and no signs, which may be safer than the smooth road with barriers and speed warnings on curves – because drivers feel at less risk and go more slowly on the more ‘dangerous’ road. And some people love risk, and will push more in a safer car to get that buzz. Car drivers give less room to a cyclist in a helmet who gives clear signals than to the unprotected one who looks and is more unpredictable. Also paradoxically, if we concentrate on improving driving skills and making it harder to get a driving licence, or try to regulate what kind of vehicle a new driver can drive or insure, the really bad drivers will drive unlicensed and uninsured.
1. Watch this on Youtube, though I've probably spoiled it for you now! http://www.youtube.com/watch?v=2pK0BQ9CUHk
‘The road, more than simply a system of regulations and designs, is a place where many millions of us, with only loose parameters for how to behave, are thrown together daily in a kind of massive petri dish in which all kinds of uncharted, little-understood dynamics are at work. There is no other place where so many people from different walks of life – different ages, races, classes, religions, genders, political preferences, lifestyle choices, levels of psychological stability – mingle so freely.’(p.6)
I’ve written a personal take on this book in my articles section. This review is a summary of its themes, and I hope will encourage more people to read it.
I learned a lot from Traffic, like the fact that traffic has been a problem for thousands of years. In ancient Rome, for example, carts were only allowed into the city at night to relieve congestion, but then kept everyone awake with the noise. There were complaints about speeding in medieval England. 1879 saw 5 hours of gridlock in New York. I like the way Vanderbilt draws on physics, mathematics, biology, sociology and psychology to explore different facets of traffic, from the pulsing of traffic jams to ant motorways to what’s really going on in the heads of drivers – and why driving and using a mobile phone is such a problem. It ranges round the world, giving us a front seat, and alarming, view of driving in Mumbai, London, Beijing and Los Angeles, among other places.
Driving is more complicated and skilled than we realise, Vanderbilt points out. He reports on how difficult it is to teach robots to drive in urban traffic, when there are countless situations to assess and choices to make: is that car parked or the back of a stationary queue? Who goes first when several cars arrive at a roundabout at the same time? How do you tell if a pedestrian is about to walk out in front of you? Drivers must cope both with the traffic laws of the particular country they’re in, and the unwritten rules and customs. For example, in the UK, most motorists routinely break the law by exceeding 70 mph on motorways, yet they’ll stop at a red light even if they can see it’s completely clear to proceed.
The counter-intuitive idea that removing signage in urban areas improves safety has been reported widely now, but it’s still interesting to read Vanderbilt’s description of it in action in various places. It helps persuade drivers that the road is not their space, specially where it goes through a village or community. In the UK, the speed limit sign is often the only thing which marks the fact that you’re driving through a village. The road itself still looks like the same highway rolling ahead of you.
A lot of driver behaviour is motivated by a sense of fairness. People should obey the rules, and not get an advantage over us. Vanderbilt discusses this in the context of merging for roadworks, where those who merge early get very angry with those who merge late, even though the quickest way for all traffic to get through is to use both lanes up to the point of merger, and then to merge in turn. Studies of queuing (yes, there are such things!) show that people prefer a single line to multiple ones even if having multiple ones is quicker, because it’s stressful seeing others get served/there before you when they came later. There’s an interesting discussion of why the other lane in a traffic jam always seems to move quicker. Apparently, though a car has as many passing events as overtaking events in congested traffic, that car will spend more time being passed by cars than passing them. Queues are like accordions, which stretch and compress. When you’re in the compressed one for several minutes, many cars sail past. When you’re in the stretched lane, it doesn’t take much time for you to pass them, and we aren’t so aware of the cars we’re passing, because we’re making good progress.
'You’re not stuck in a traffic jam. You are the traffic jam.’ German advert
Instances of road rage (or ‘traffic tantrums’, as Vanderbilt calls them) hit the headlines, but ‘normal’ drivers often show a lot of aggression too. They honk or make rude gestures or swear or shout when another driver makes a mistake. Pedestrians shout at speeding cars, drivers honk at oblivious pedestrians, cyclists annoy drivers and pedestrians, and also get threatened by them. The question, Vanderbilt says, is not why some drivers are homicidal maniacs but ‘why we all act differently.’ In traffic, he says, ‘we struggle to stay human.’ (21) This is partly because being in a car makes us mute. We can’t hear, or read facial expressions easily, or communicate. Human beings aren’t designed to move faster than 20 mph, we can’t make eye contact at that speed, or it’s not safe to look. Are we being honked because we’ve done something wrong, or as a thank you, or because our petrol cap is open? We quickly interpret other drivers’ mistakes as rude or hostile or totally incompetent, and draw on stereotypes to judge them: SUV driver! Women! Yet we don’t judge ourselves for doing the same thing.
Being a driver we are generally anonymous, stuck behind other drivers. So perhaps, Vanderbilt says, getting angry and sounding off helps us feel a sense of identity. Passengers don’t have the same issues, and solo drivers – unless in open-tops - are more aggressive. Vanderbilt compares this to behaviour online: ‘Being in traffic is like being in an online chat room under a pseudonym. … the normal constraints of life are left behind.’(p.27) Psychologists speak of the ‘online disinhibition effect’, where the ‘individual swells with exaggerated self-importance.’ Whether online or on the road, there is no consequences for being rude or harsh. You can ‘flame’ someone and sign off.
There’s a perception that we can talk on the phone and drive perfectly well. A driver on the phone may lower their speed and drop back. Their eyes may stay on the road once they’ve established the call, and they feel in control of their car. Except that even if their eyes are on the road, their mind isn’t. When we try and do two things at once, the quality of both tasks drops, yet we don’t realise how distracted we are. People may be able to cope with standard driving in this mode, but they can’t deal with the unexpected. The largest analysis of driving to date, says Vanderbilt, showed that nearly 80% of crashes and 65% of near crashes involved drivers not paying attention to traffic for up to 3 seconds before the event. A 2-second look away is enough for them to start to lose track, yet drivers drive as if world will not have changed when they look back, as if it was ‘live pause’ on the TV. But we only need to take that 2-second glance away at the wrong time for a crash to happen. Dialling or texting from a phone is clearly risky, but so is anything which takes our eyes and mind off the road, even lots of short glances.
One problem is that we don’t get feedback on our driving. When negative feedback comes our way on the road, we explain it away or quickly forget it. A speeding ticket is because police have to make a quota, a driver honking is them being aggressive, our passenger flinching or pressing imaginary brakes is about their nerves, a crash is bad luck. Other drivers are bad or incompetent and need their behaviour controlled through strict laws, but if the law catches us, it’s unfair, and why don’t the police go after the real criminals? In fact, we may be driving riskily and badly - using a phone, tailgating, speeding, not wearing a seat-belt. But every day we drive without incident, every journey that nothing bad happens, we’re reinforced in our belief that we are driving well. If we do have a near miss, it doesn’t necessarily teach us to drive more safely, it just confirms that we have the skill to get out of trouble.
When people do get feedback, though, it can be something of a surprise. Vanderbilt describes the use of DriveCam. A camera in the car is triggered by braking or sudden turns, and captures the driving behaviour which leads to near misses. It’s related to the thinking of H W Heinrich, an insurance investigator whose 1931 book suggested that in industrial accidents, for every 1 fatality or major injuriy in the workplace, there were 29 injuries and 300 near-miss incidents without injury. He argued that to avoid the one event at top of triangle, industries should tackle the many small events. While his theories are controversial, Vanderbilt acknowledges, the idea that near misses are scaleable to more serious incidents remains powerful for traffic, given how often human factors are responsible. One big study found that for every 120 incidents, there were 11 minor injury crashes and 1 serious crash.
DriveCam shows how often drivers are indulging in unsafe, careless behaviours - hands off the wheel, falling asleep, drifting in lane. Mostly, luckily, they get away with it. For example, there’s the van driver using his phone whose camera is triggered when his van drifts off the road. He saves himself, but 12 feet away there are children on the pavement. The driver is reinforced in his belief that he’s a good driver because he didn’t crash, yet it was only luck which stopped him hitting the children. If he had done, he might have said it was sheer bad luck that they were in the wrong place at the wrong time. Yet this would have been a perfectly avoidable crash if he’d kept his mind on the road.
One of the things which goes when drivers are on the phone or doing other things as they drive, is awareness of the wider environment. Vanderbilt refers to the moonwalking gorilla experiment,1 where people told to focus on how many passes a basketball team makes don’t spot the gorilla moonwalking through the scene. When we’re concentrating on one thing, we miss others. We’re limited in how much we can pay attention to. ‘Looked but did not see’ accidents are common, specially with motorbikes.
Indeed our perceptions as drivers aren’t terribly reliable. Particularly as cars get quieter and radios etc get louder, it’s hard to know what speed we’re doing. A flashing speed sign causes drivers to slow down because they haven’t realised how fast they were going, or that there was a speed limit, or both. We don’t always estimate other cars’ speed accurately, either. Because of the way our brains are wired, we think a small car is further away than a large truck, or assume a large object is going more slowly than a small one. For example, a jumbo jet seems very slow as it takes off compared to a small plane.
There is an interesting section in the book discussing the relationship between traffic fatalities and the economy as represented in a nation’s Gross Domestic Product. Though a low GDP means less wealth, fewer cars and low fatalities, it isn’t a straightforward link. In fact, research suggests that traffic danger is more closely aligned with corruption. If the legal authorities aren’t seen as legitimate, or the laws seem unreasonable, people are less likely to obey. While there’s a difference in traffic danger between countries which have a similar GDP – eg Belgium has twice as many traffic fatalities as the Netherlands – there is a correlation with corruption as measured on the Transparency International data. Countries with low corruption - Sweden, New Zealand, Singapore, Norway, Finland - are the safest places in which to drive. France has improved its safety as it has tackled its culture of traffic ticket fixing. I don’t know enough to evaluate this research, but it raises the interesting point that: ‘If GDP and traffic fatalities are somewhat related, and GDP and corruption are somewhat related, and traffic fatalities and corruption seem to be the most clearly related, then fighting corruption may be the best way to lower traffic fatalities and raise GDP.’(p.242)
To generalise a number of points from the book: driving is not something we do independently of other people. Perhaps we can handle a car well at speed, but we share the road with new drivers, lost drivers, distracted drivers, young or vulnerable pedestrians. What’s best for me in traffic – nipping down the rat run and saving time on my journey - may not be best for the common good: the noise for residents of that street, the cost of repairing a road not built for much traffic. If I tailgate or weave lanes on the motorway, I can send pulse waves further down the traffic queue which create a jam. For all the complaints about the unfair costs on the poor motorist, drivers don’t pay much at all towards the real cost of road maintenance, congestion, pollution, or the cost to the economy (let alone the human consequences) of crashes, fatalities, delays.
Yet, paradoxically, safety features can make drivers drive worse. Vanderbilt contrasts driving over a narrow mountain track with sheer edges and no signs, which may be safer than the smooth road with barriers and speed warnings on curves – because drivers feel at less risk and go more slowly on the more ‘dangerous’ road. And some people love risk, and will push more in a safer car to get that buzz. Car drivers give less room to a cyclist in a helmet who gives clear signals than to the unprotected one who looks and is more unpredictable. Also paradoxically, if we concentrate on improving driving skills and making it harder to get a driving licence, or try to regulate what kind of vehicle a new driver can drive or insure, the really bad drivers will drive unlicensed and uninsured.
1. Watch this on Youtube, though I've probably spoiled it for you now! http://www.youtube.com/watch?v=2pK0BQ9CUHk