What Your Driving Habits Say About You Tom Vanderbilt, author of Traffic, talks about the psychology of driving and the engineering of roadways. He explains some contradictory traffic truths: why roundabouts are safer than intersections and how slower can actually be faster.

What Your Driving Habits Say About You

What Your Driving Habits Say About You

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Tom Vanderbilt, author of Traffic, talks about the psychology of driving and the engineering of roadways. He explains some contradictory traffic truths: why roundabouts are safer than intersections and how slower can actually be faster.


You're listening to the Talk Of The Nation, Science Friday. I'm Ira Flatow. Up next, a look at possibly the most complicated and potentially maddening things most of us do on a regular basis. What would you say that is? It's, yep, driving. Driving, you know, it starts out as a mundane activity. You get in your car, you turn the key on, you back out of the driveway, slowly hit the road, but then what happens - right? You find drivers who don't give a darn about the rules. People who cut you off, road signs that don't make sense, road rage - find all of this, you name it, and I'm sure we can put a lot more in there. And we will this hour because we're going to be talking about driving. What kind of driver are you? What drives you crazy on the road?

My next guest has gathered a lot of this research about driving habits into his new book. Let me introduce him. Tom Vanderbilt writes about design and technology for Wired and Slate and the New York Times. His new book is called "Traffic: Why We Drive the Way We Do and What It Says About Us." He joins us from Georgia Public Broadcasting. Thanks for being with us.

Mr. TOM VANDERBILT (Author, "Traffic: Why We Drive the Way We Do and What It Says About Us"): Great to be here.

FLATOW: This is a very thick book and you've taught - you've chronicled everything we ever do on the road.

Mr. VANDERBILT: It could be five times as large.

FLATOW: It is amazing, how many things people do while they're driving, isn't it? And the things that they do.

Mr. VANDERBILT: Yeah. I mean, driving alone is complicated enough, but it's a little mind-boggling that we're now throwing things like, you know, texting and cell phones into the mix. And this is why in some ways I try to drive as little as possible because of the things I've seen other people doing. But it's easier to ride in - to write about traffic than to sit in it, basically.

FLATOW: I have to admit that I, you know, one of the things I hate most when I drive to see, I mean, I think this is like - it's what called the late merger. You start out with the late merger. I have to admit, you know, in all honesty, I have tried it a couple of times and I felt terrible about it when I was - I've been done. Tell us about the late merger.

Mr. VANDERBILT: Well, you know, I used to be you. I was, you know, I was born in the Midwest. I'm a polite guy, I - there's a bottleneck coming. There's two lanes going to one. I would stay in that long queue, and I didn't want to be that person going all the way to the front. And one day, I was a little bit pressed for time and I did it and felt sort guilty about it. And tried to look for reasons why I did what I do or maybe why there even were late and early mergers. And what I found, when I looked into the - some of the research on this, is that when engineers have set up special systems that sort of eliminated the entire concept of a late and early merge, and had people go to that merge point and then go one on one, that what they call through put, through the whole bottleneck, was actually faster. And so, you know, there's just this thing going on that what see through the windshield, and kind of our notions of polite and impolite, don't necessarily equal out to what's actually happening in the whole system.

FLATOW: So you're saying that it's actually better for the whole system to be a late merger?

Mr. VANDERBILT: If we got rid of that entire concept and you know, everyone use - I mean, that's spare road capacity there. And it also creates, you know, sort of a longer queue if everyone jumps over early and that queue sometimes goes back even past the signs warning that there's a merge coming up. And on a highway, that's very dangerous to ask people to stop unexpectedly. So I'm not saying the late mergers were acting altruistically.

FLATOW: Right.

Mr. VANDERBILT: But, you know, if we get the message out there, I think we could sort of change the entire behavior.

FLATOW: But so many things on the road, I've put into the category of the rules are made for you but not for me, and you're a sucker for paying attention to that. That would be, certainly a late merger would fall into that one, but there are whole bunch of other things like that, you know, left-hand turns, that sort of thing.

Mr. VANDERBILT: Well, I think no issue is more heated in American driving culture than the left lane is for passing. And I mean, we often find people sort of sitting in the left lane here and - but this raises sort of this fundamental question that you find people driving fast in the left lane who come upon someone going the speed limit and they say hey, you know, you're violating the law by not getting over for passing traffic. And this is someone going, you know, 15 miles over the speed limit, which technically is the law. So you're finding these sort of laws and beliefs and norms all kind of coming into conflict. And multiply this times a thousand and times 75 miles an hour, and you can see how, just how complex the whole thing really is.

FLATOW: That's because I think we all do not assume that 15 miles an hour over the speed limit is really speeding because so many people are doing it these days.

Mr. VANDERBILT: It's a funny thing why some things, we adhere more closely to another. I means, we're sort of rigid about stoplights and you know, the middle of the night you pull to a stoplight, you don't necessarily go through it, if no one else is coming. You don't violate that norm so much as you violate the norm of speed. But in part, that's just because we're quite overconfident on the road, and we aren't even aware - I would suggest - of things like stopping distance because generally, we don't have to do things like stop in an emergency. We lose the sense of what our vehicle's actually capable of.

FLATOW: Mm-hm. Is our culture different than others around the world in how we drive?

Mr. VANDERBILT: Well, totally. I mean - and some of it is just, you know, sort of the density. I mean, a place like Delhi and the vehicle mix. I mean there are 48 different modes of travel on the streets of Delhi, and then throw into that something like a cow. And cows, you know, famously roam the streets, and they'll sit on the traffic islands.

They actually prefer to sit on the traffic islands because they're sort of warm, and the passing vehicles keep the flies away, I was told by...

(Soundbite of laughter)

Mr. VANDERBILT: And you know, the - Delhi's top traffic cop told me, now this is - it's dangerous, yes. But it's also traffic calming, because...

FLATOW: Right.

Mr. VANDERBILT: You know, it's novelty and no one wants to hit a cow.

FLATOW: Right, right. Talking with Tom Vanderbilt, author of "Traffic: Why We Drive the Way We Do, and What It Says About Us." You know, a lot of times, we're very quick to judge people, and that is, as I say, sometimes we then do these things ourselves. And sometimes - one great example of this is, I hate rubbernecking.

I hate people who slow down to see a tire being changed, you know? And it could be in the other direction. Yet, when I'm in that line, it gets to that spot, I say to myself, if I had to slow down, that person behind me is going to have to slow down.

Mr. VANDERBILT: Yes, I mean, this is exactly what...

FLATOW: Right.

Mr. VANDERBILT: I mean, Thomas Shelling wrote about this - Nobel prize winner. I mean, traffic fascinates him and, you know, you multiply that 10 seconds that each person takes by that line of a hundred vehicles, and it adds up to a lot of time. And if we could somehow agree beforehand not to take that look.

And they've tried to do things like set up screens that block the crashes. But sometime people just sort of look at the screens themselves, and those are sort of interesting and, you know...

FLATOW: Yeah, let's go see - let's go to the phones, lots of folks want to talk about driving. Paul in McLean, Virginia. Hi.

PAUL (Caller): Hi, Ira.

FLATOW: Hi there.

PAUL: Hey, listen. When I come to a traffic stop, a red light, I pull up close to the car in front of me, about two, three inches from him. And I notice a lot of people leave 10, 20 feet, and I think that's impolite to the cars behind because if everyone pulled up close, you could probably move sometimes into another lane. And I wonder, you know, why do they do this, and what can be done about it?

FLATOW: You don't think that's an aggressive thing to do, to pull up to two inches behind somebody?

PAUL: No. I think it would be aggressive only if I hit them. But I don't hit them.

(Soundbite of laughter)

FLATOW: OK. Tom, what do you think?

Mr. VANDERBILT: Well, I mean, yeah. He's right. That is wasted capacity and those protected green phases as they're called, are in short supply time wise and you know, often you find yourself sitting through three of those things. So, I don't really recommend tailgaiting in general, but I think tailgaiting, when stopped at red lights, would be OK.

FLATOW: Mm. Why don't we see more timed lights, you know, 30 mile an hour, sometimes I know driving, if you time the light just right, you can go straight through all these greens. But then it sort of seems, wow, someone just messed the whole thing up on one block.

Mr. VANDERBILT: Yeah, I mean, sometimes it just could be bad engineering, but you know, in Los Angeles, they - Los Angeles, they're really good at this. They've been working on this for decades, they've had traffic for decades, obviously. But there's this fundamental problem of, you know, on a grid system there are a lot of other cars going, kind of intersecting that traffic...

FALTOW: Mm-hm.

Mr. VANDERBILT: Also asking the same question; Why am I not getting that green wave?

FLATOW: Right.

Mr. VANDERBILT: And you can sort of work it out mathematically, I've been told. But you know, sometimes there's just a saturation problem where there's just too many cars trying to use one intersection.

FALTOW: Right.

Mr. VANDERBILT: And it breaks down.

FLATOW: What do you think about these new - what - in the northeast, they're called the E-ZPass, these - you know, these electronic metering systems for cars, so that you don't have to go through the toll booth anymore. You just zip right through there. Has that helped a lot?

Mr. VANDERBILT: Yeah, I...


Mr. VANDERBILT: Well, I think so. I mean, because that's the classic bottleneck, is the toll plaza, and I'm sort of shocked in New York, how many people actually don't use easy pass, and I'm sort of definitely one of those smug easy-pass users that whisks by. Although sometimes, you know, you're just speeding up entry to another bottleneck.

You're kind of - there's something up ahead, but that whole thing is sort of called ITS, Intelligent Transportation System. Just using technology, computers, etc., sensors to find ways to manage the flow better.

FLATOW: You know, there's even talk that they may build these things sort of into the cars now, into the future cars, so that the people will know where you are any time of the day.

Mr. VANDERBILT: Yeah, I mean, we're seeing that as well. And well, the systems have already emerged for things like adaptive cruise control, which can sort of measure exactly how far away the car is, and sort of - and studies of simulations have shown that if everyone had that, the highway would actually flow sort of better...

FALTOW: Mm-hm.

Mr. VANDERBILT: Because there's individual drivers who make a lot of choices about speed and varying speeds and lane changes, and if we could sort of achieve a more, you know, homogeneous flow...

FALTOW: Mm-hm.

Mr. VANDERBILT: But the best thing would be definitely to take the human away from the wheel, at least in the highway environment.

FLATOW: Do you think that's possible? I mean, to make automatic cars that drive themselves?

Mr. VANDERBILT: Well, in that kind of very simple environment. But you know, DARPA, the Defense Agency's research arm has been, you know, doing this autonomous vehicle race a couple times.

And the last one they did was an urban challenge, and teams of very clever people from the top universities worked for years with a lot of money spent to create these autonomous vehicles that could drive themselves in a city environment, and the end of all this they, you know - they basically got cars that drove sort of slowly and crashed into each other, and would have basically gone haywire if there were things like pedestrians...


Mr. VANDERBILT: Present. I mean, so we're getting there, but it would be a long way off for something like that.

FLATOW: All right. Let's go to Elliot in Berkley. Hi, Elliot.

ELLIOT (Caller): Hello. Quick question that you could answer later. Does IQ and driving skill match? But main question, zipper merge seems to be the solution to forced merges. Is there a way to teach and enforce zipper merges to speed traffic?

FLATOW: Zipper merge means alternating left and right cars?


FLATOW: Yeah. Can we - that's a good question, Tom.

Mr. VANDERBILT: Well, you know, it - every situation is different. So, you know, even with a late merger marker mending, when traffic is flowing lightly, there's no need for that sort of last-minute merge. You should - it would really work better if everyone merged well ahead of the merge point.


Mr. VANDERBILT: So, traffic, you know, it always behaves differently and you know, applying the wrong medicine in the wrong place can sort of, you know...


Mr. VANDERBILT: Be worse than the cure.

FLATOW: Let's go through some of these interesting observations you have in your book. Let's talk to first - walk - let's talk about it a few of them, for example. More people are killed legally crossing in a crosswalk than jaywalking. Wow.

Mr. VANDERBILT: That was in New York City, you know, and it kind of fascinated me that more people are killed in the crosswalk when they have the signal than when they don't. So, you know, there's just something about - cars are unfortunately given the green light to move ahead.

At the same time, pedestrians are given the walk signal, and turning cars, basically often - you know, there's a - they're not anticipating pedestrians. They're focused more on the green light, that maybe the roof pillar of the car is obstructing visibility.


Mr. VANDERBILT: Maybe they're on their cell phone.

(Soundbite of laughter)

Mr. VANDERBILT: But this is, you know, the classic Ratso Rizzo problem from the film "Midnight Cowboy," you know, hey, I'm walking here.


Mr. VANDERBILT: This is something every New Yorker has to deal with every day.

FLATOW: Yeah. Don't make any eye contact. That's what we do here in New York. If we - I don't see you, then I don't get hit. And children, you also observed the children-at-play signs. Those signs do not reduce speeds or accidents. I guess that's sort of like the baby-on-board thing?

Mr. VANDERBILT: Yeah, you know, and there's this great big book called "The Manual of Uniform Traffic Control Devices," which is the engineering bible. And if you look in there, it's sort of - they basically recommend not to use it because it just hasn't really been shown to produce the effects, and usually it's sort of beleaguered residents who are trying to get people to slow down...


Mr. VANDERBILT: And neighborhoods who put these things up and you know, you can try, but getting drivers to slow down is just one of these fundamental problems.

FLATOW: Yeah. Talking with Tom Vanderbilt, the author of "Traffic: Why We Drive the Way We Do and What It Says About Us," on Talk of the Nation: Science Friday from NPR News. Do speed bumps work? I mean, there are people that just go zooming and banging up on speed bumps but don't slow down.

Mr. VANDERBILT: I mean, you have people, you know, suing the city for ruining their suspension. There's that problem. But then, there's some evidence that they speed up in between the speed bumps, so you might be achieving success in one place but then, just swapping it out for an increased risk in the other place.

So, there's kind of a whole new school of what's called sort of psychological traffic calming that, you know, maybe instead of speed bumps, maybe the road should be narrower to begin with, or maybe even removing that white divider lines between the lanes, and it sort of confuses drivers a little bit, makes them slow down.


Mr. VANDERBILT: Studies in England actually showed that they drove further apart, when the lines weren't there, than when the lines was there. I mean, the line, in a way, sort of makes you stop thinking for yourself.

FLATOW: Right. What about speed traps? Do people pay attention to those? They - you know, or those phony cops they put up sometimes on the road.

Mr. VANDERBILT: When they see them, I suppose, although a good speed trap, you don't speed. But you know, there's a - I think there's a reason those are always posted at the entrance to small towns, and maybe they're trying to raise money for the town.

But there is this problem, you know, driving - when you're driving for a long time at a certain speed, something called a speed up adaptation happens, and it takes you longer to realize when you're trying to slow down, it takes you longer to get to that speed you want. It's sort of been called the treadmill effect. When you're on the treadmill at the gym and you're running, and then you press stop and the room sort of goes backwards for a minute.

FLATOW: Right.

Mr. VANDERBILT: The neurons in your brain are adjusting to the new speed, but there's still sort of a forward motion happening there, so...

FLATOW: Huh. You also write that men honk more at women, and men and women honk more at women than at men.

Mr. VANDERBILT: Well, this is - you know, the stop light is a great place outside of the lab for applied psychology research, and you can...

(Soundbite of laughter)

Mr. VANDERBILT: You know, the light turns green, you wait to see what that second car does when the first car doesn't move. And there's all sorts of really curious patterns that emerge, and yes, men do honk more.

When you have a convertible, the people honk less. There's a theory that they're less anonymous, and they feel less protected, and people honk more at novice drivers; more expensive cars honk more at less expensive cars.


Mr. VANDERBILT: And these studies have been done in a kind of a fascinating variety of permutations.

FLATOW: Right. And one last question about drunk driving. Do we know when we're drunk, when we drive? Do we - can we recognize other drivers who are drunk?

Mr. VANDERBILT: I mean, well - I mean, the police have certain things they look for, I mean...

FLATOW: I mean, by the patterns of - yeah, I guess so. I guess that's how...

Mr. VANDERBILT: I mean, there's definitely some weaving behavior. But you know, I don't think we even recognize the extent to which we're distracted when we're on a cell phone conversation. When you're punching the dial...


Mr. VANDERBILT: Dialing the buttons, you're quite aware of the distraction.

FLATOW: Right.

Mr. VANDERBILT: But when you're actually in the conversation, there's sort of no way to know. And this is why it's a great problem, of course.

FLATOW: Yeah. And then they keep - the people want their video screens on their cars now to watch.

Mr. VANDERBILT: Yes. In the back seat for now. But they'll probably - they're probably making their way into the front seats.

FLATOW: Well, if you have an iPhone and you have your video playing on it, it could be sitting right there in your dashboard. Or any of these cell phones.

Mr. VANDERBILT: Yeah, I mean. No, I mean. Texting while driving is definitely a part of the traffic culture, which is not a good thing.

FLATOW: Not a good thing. Well, we've run out of time. Tom, I want to thank you for joining us. Great book, "Traffic: Why We Drive the Way We Do and What It Says About Us," written by Tom Vanderbilt, who is author for Wired and the New York Times. Thanks for taking time to be with us today.

Mr. VANDERBILT: Thank you.

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Navigating The Science (And Sociology) Of 'Traffic'

Navigating The Science (And Sociology) Of 'Traffic'

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Morning traffic is a perennial problem in New York. Timothy A. Clary/Getty Images/AFP hide caption

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Timothy A. Clary/Getty Images/AFP

Morning traffic is a perennial problem in New York.

Timothy A. Clary/Getty Images/AFP

Unexpected Driving Tips from Traffic

  • The more congested a highway is, the less likely one is to save any time by switching to a faster lane.
  • Though it may seem rude, merging at the very point where a lane ends allows traffic to more rapidly.
  • In some cases, slowing down for a yellow light rather than speeding up may increase one's odds of getting into an accident.

In Traffic, Tom Vanderbilt writes that road rage does not necessarily have to be a bad thing — letting out one's frustrations in a semi-private space may actually be therapeutic, so long as it does not result in conflict with other drivers. Kate Burton/Knopf hide caption

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Kate Burton/Knopf

"How's my driving?" ask the backs of eighteen-wheelers. Writer Tom Vanderbilt thinks it could be better.

Vanderbilt's book Traffic: Why We Drive the Way We Do (and What It Says About Us) explores the sociology of driving — why roads are most congested on Saturdays, what percentage of traffic is drivers simply looking for parking, why new cars crash more often than old ones. The book is based on research and interviews with driving experts and traffic officials around the world.

Among Vanderbilt's findings is the discovery that "late merging" may actually cause traffic to move more quickly, contrary to popular belief. When a sign warns that the lane will end in a given distance, standard driving etiquette causes many to move over as promptly as possible. However, if everyone were to merge at a single point when the lane ends, the road would get maximal usage and lane changes would become more orderly. The result would be traffic that moves 15% faster than current behavior allows.

"If people were told exactly to not leave the lane that was closing until the very point it actually did close, and then we did a nice alternating merge — it would be faster," says Vanderbilt. "Another benefit would be the queue of vehicles stretching back from the construction site would be smaller."

Vanderbilt also argues that round-abouts may be safer than traditional stoplight intersections. Though traffic circles may seem confusing, they have fewer "conflict points," places where cars can physically hit an object or person. Intersections have 32 of these conflict points, where round-abouts only have 16. The round-about is particularly safe because it completely eliminates the left-turn, one of the most dangerous driving maneuvers.

Vanderbilt is a New-York based writer who covers topics such as design, technology, science, and culture for Wired, Slate, and The New York Times.

Excerpt: 'Traffic'

Traffic: Why We Drive the Way We Do (and What It Says About Us)
By Tom Vanderbilt
Hardcover, 416 pages
List Price: $24.95

Why I Became a Late Merger (and Why You Should Too)

Why does the other lane always seem to be moving faster?

It is a question you have no doubt asked yourself while crawling down some choked highway, watching with mounting frustration as the adjacent cars glide ahead. You drum the wheel with your fingers. You change the radio station. You fixate on one car as a benchmark of your own lack of progress. You try to figure out what that weird button next to the rearwindow defroster actually does.

I used to think this was just part of the natural randomness of the highway. Sometimes fate would steer me into the faster lane, sometimes it would relinquish me to the slow lane.

That was until recently, when I had an experience that made me rethink my traditionally passive outlook on the road, and upset the careful set of assumptions that had always guided my behavior in traffic.

I made a major lifestyle change. I became a late merger.

Chances are, at some point you have found yourself driving along the highway when a sign announces that the left lane, in which you are traveling, will close one mile ahead, and that you must merge right.

You notice an opening in the right lane and quickly move over. You breathe a sigh, happy to be safely ensconced in the Lane That Will Not End. Then, as the lane creeps to a slow halt, you notice with rising indignation that cars in the lane you have vacated are continuing to speed ahead, out of sight. You quietly seethe and contemplate returning to the much faster left lane–if only you could work an opening. You grimly accept your condition.

One day, not long ago, I had an epiphany on a New Jersey highway. I was having a typical white-knuckle drive among the scenic oil-storage depots and chemical-processing plants of northern Jersey when suddenly, on the approach to the Pulaski Skyway, the sign loomed: LANE ENDS ONE MILE. MERGE RIGHT.

Seized by some rash impulse, I avoided the instinctual tickle at the back of my brain telling me to get in the already crowded right lane. Just do what the sign says, that voice usually counsels. Instead, I listened to another, more insistent voice: Don't be a sucker. You can do better. I plowed purposefully ahead, oblivious to the hostile stares of other drivers. From the corner of my eye I could see my wife cringing. After passing dozens of cars, I made it to the bottleneck point, where, filled with newfound swagger, I took my rightful turn in the small alternating "zipper" merge that had formed. I merged, and it was clear asphalt ahead. My heart was beating faster. My wife covered her face with her hands.

In the days after, a creeping guilt and confusion took hold. Was I wrong to have done this? Or had I been doing it wrong all my life? Looking for an answer, I posted an anonymous inquiry on Ask MetaFilter, a Web site one can visit to ask random questions and tap into the "hive mind" of an anonymous audience of overeducated and overopinionated geeks. Why should one lane move faster than the other, I wanted to know, and why are people rewarded for merging at the last possible moment? And was my new lifestyle, that of the late merger, somehow deviant?

I was startled by the torrent of responses, and how quickly they came. What struck me most was the passion and conviction with which people argued their various cases–and the fact that while many people seemed to think I was wrong, almost as many seemed to think I was right. Rather than easy consensus, I had stumbled into a gaping divide of irreconcilable belief.

The first camp–let us name it after the bumper sticker that says practice random acts of kindness–viewed early mergers as virtuous souls doing the right thing and late mergers as arrogant louts. "Unfortunately, people suck," wrote one Random Acts poster. "They'll try whatever they can to pass you, to better enjoy the traffic jam from a few car lengths ahead of you. . . . People who feel that they have more pressing concerns and are generally more important than you will keep going, and some weak-spined schmuck will let them in further down, slowing your progress even more. This sucks; I'm afraid it's the way of the world."

Another camp, the minority camp-let's call them Live Free or Die, after the license-plate motto of the state of New Hampshire-argued that the late mergers were quite rationally utilizing the highway's maximum capacity, thus making life better for everyone. In their view, the other group's attempts toward politeness and fairness were actually detrimental to all.

It got more complicated. Some argued that late merges caused more accidents. Some said the system worked much better in Germany, and hinted that my dilemma perhaps revealed some national failing in the American character. Some said they were afraid of not being "let in" at the last moment; some said they would actively try to block someone from merging, the way truckers often do. So what was going on here? Are we not all driving the same road, did we not all pass the same driving tests? What was puzzling was not just the variety of responses but the sense of moral righteousness each person attributed to his or her highway behavior, and the vitriol each person reserved for those holding the opposite view. For the most part, people were not citing traffic laws or actual evidence but their own personal sense of what was right.

I even found someone claiming to have had a conversion experience exactly the opposite of mine. "Until very recently, I was a 'late merger,' " wrote the author, an executive with a software company, in a business magazine. Why had he become a born-again early merger? "Because I came to realize that traffic flowed faster the sooner people merged." He used this as a metaphor for successful team building in corporate America, in which "late mergers" were those who consistently put their own opinions and motives above the greater company. "Early mergers," he wrote, could help push companies to their "maximum communal speed." But did traffic flow faster when people merged sooner? Or did it just seem more noble to think that it did?

Excerpted from Traffic by Tom Vanderbilt Copyright © 2008 by Tom Vanderbilt. Excerpted by permission of Knopf, a division of Random House, Inc. All rights reserved. No part of this excerpt may be reproduced or reprinted without permission in writing from the publisher.

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