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Erel Avineri of the Centre for Transport & Society looks at traffic from the perspective of a Human, not an Econ. Standard economic models of people seem to do a poor job anticipating what people do on the road. Using models from behavioral economics and psychology, Avineri is interested what influences our boundedly rational travel behavior. What kind of feedback might change it? What effect do our interactions with others on the road have? According to his web site, he is “exploring how to change travellers’ behaviour in a way that does not limit their freedom of choice (for example by ‘nudging’).” In some interesting research, he applied the lessons of loss aversion to everyday decision making by travelers. We asked Avineri to share his insights with Nudge blog readers.

Continue reading the post here.

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Traffic guru Tom Vanderbilt, author of Traffic (appropriately), fills in the blanks on the fake potholes. They are part of a marketing campaign for car suspension systems (which a Nudge blog reader noticed too).

In reality, they were used as part of an advertisement for Pioneer Suspension, a vehicle suspension supplier. The ad was intended to suggest to drivers that, with Pioneer Suspension fitted to their vehicles, they would enjoy a smooth ride even on rough roads. Information about the ad published on the Ads of The World website…According to Ads of the World, the ad was created by Advertising Agency, Y&R Everest, Mumbai, India in 2007. It is unclear under what conditions or circumstances the advertising tactic was carried out. As many commentators have noted, unless the tactic was used in very controlled conditions, such fake potholes could actually be quite dangerous. Approaching drivers could swerve suddenly to avoid the “pothole” and serious accidents could result.

More at How We Drive.


More nudges from the world of traffic. Try these when speed bumps, real or fake, don’t work.


From what we can tell so far, they are fake.

Hat tip: Christopher Hsee


The always interesting Traffic author Tom Vanderbilt points out a possible nudge solution for “left-lane” bandits, who are drivers that stay in what is supposed to be a lane for passing slower cars.

One issue, of course, is that for some people, the fastest drivers, the left-lane becomes their de facto lane, and they may force out dozens of drivers (necessitating all kinds of disruptive lane changes) for their own benefit. This raises another possibility. The road could be grooved in such a way, as in Japan’s Melody Road (that’s an engineer inspecting the road pictured above) to produce a certain sound at a certain speed. Grooving could presumably be laid so that drivers going over a certain speed produced a really grating, revulsive sound (music might be tricky as one person’s annoyance would be another’s delight). In a sort of Nudge-like way, drivers could choose to stay in the unpleasant lane if they wished, but they would be subtly steered toward the more harmonic travel lanes.

A video of Melody Road is below. (Unless you speak Japanese, you’re only going to hear the sweet sound of asphalt)



It’s a nudge straight out of the future, or at least a science fiction fantasy: Designer Hanyoung Lee’s “Virtual Wall,” a ten-foot high curtain of plasma laser beams. At the moment, there are no plans to produce these on a mass scale. In fact, it hasn’t even gotten off the drawing board.

Hat tip: Sendhil Mullainathan


Tom Vanderbilt links to a web site Platewire that tries to use social shaming to nudge drivers to respect cyclists, pedestrians, and other drivers better. Lots of discussion about it at John Tierney’s science lab. Two years ago, Lior Stahilevitz of the University of Chicago law school proposed extending the 18-wheeler “How’s My Driving?” campaign to a civil enforcement and fine system. Here’s a link to an audio of a talk he gave at the Law School with links to his paper inside.

Addendum: Instead of Platewire, there’s Jimmy Justice – the parking vigilante, ahem human nudge, embarrasses violators no matter how politically powerful or connected they may be.

Hat tip: Philip Frankenfeld


Reader Francis King wrote to say Nudge could’ve included some more traffic examples.

There are exactly two ways of managing traffic – the heroic and difficult way, and the thoughtful and easy way. To restrain the speed of the cars, it is possible to use a speed camera. Alternatively, though it is possible to use a vehicle-actuated sign, which flashes up the speed limit if the next car is going too fast. Both have the same effect, yet one doesn’t involve fining car drivers, and ultimately taking their car license off them.

Even more than that, it is possible to create the illusion that the road narrows, but putting hedges along the road side, by hashing out part of the road surface, by using dragon’s teeth, or by putting up a gateway at the entrance to a village. A gateway, in essence is a small brick wall on either side of the road. As the road appears to narrow, so car drivers slow down, even though the road has not actually narrowed at all.

If white lines are removed from the centre of a road, this also causes traffic to slow down. Removing the footways and sharing the space between car drivers and pedestrians also causes the traffic to slow down. In both cases, this is due to the fact that traffic is no longer being given permission to drive along the road –uncertainty causes a reduction in speed. It also makes the road look better.

In Holland, most people cycle at one time or another, in the UK it is the preserve of a few. In Holland, because most people cycle, car drivers show great respect to cyclists, in the UK occasional contempt or violence. We have an international cycling team, but is doesn’t actually train in the UK, and one reason was the attitude of car drivers, when they were training on the roads.


Here in the U.S., road signs that flash the driving speed of approaching cars are a common sight, in part because they operate at two percent of the cost of traffic cameras. The clunky acronym for these things are VAS (Vehicle Activated Speed) signs. In the U.K., however, these signs don’t just tell drivers their speed. They smile at cars under the limit, and frown at cars over the limit.

Hat tip to Rory Sutherland for pointing this out in a post on the Spectator blog. You can also read Rory’s earlier piece on why politicians shouldn’t be afraid to learn from marketers, who are, after all, masters of persuasion.

No, the happy chap in the picture above is not Rory. It’s Councillor Michael McCann, the depute (British spelling) leader of South Lanarkshire Council, and member of the Scottish Labour Party.

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In Nudge, Thaler and Sunstein talk about a curve in Chicago’s Lake Shore Drive that uses a nice visual illusion to nudge drivers to slow down. Road planners in Philadelphia have been experimenting with painted illusions of speed bumps on some roads to accomplish a similar effect. From the New York Times:

The triangles are known variously as 3-D, virtual or just plain fake speed humps. They are among the latest tools in the age-old battle between drivers who exceed speed limits in residential neighborhoods and residents, law enforcement officers and government officials who want to slow them down.

Real speed humps — not to be confused with their more jarring cousins, speed bumps, a mainstay of some parking lots — are rounded mounds of traffic-calming asphalt that generally span a roadway. The virtual variety — flat pieces of plastic that are burned into the street, with the configuration of the colored lines conveying the illusion that a driver is about to cross the real thing — is less expensive ($500 each, versus $2,000), does not impede water flow and poses no threat to ambulances or other speeding emergency vehicles.

City road crews burned 10 sets of the humps into a half-mile stretch of road to tests their effects on drivers.

Before installation, Ms. Tolson said, drivers along that stretch of the two-lane road, often used as a neighborhood shortcut, were clocked averaging 38 miles per hour, 13 m.p.h. above the posted speed limit. A month later, that figure has dropped to 23 m.p.h.

Addendum: Tom Vanderbilt of How We Drive has similar thoughts to Colin. Check out Vanderbilt’s post for a bird’s eye shot of the Lake Shore Drive curve.

One of the main drawbacks is that people who live in the neighborhood or use the road regularly (and remember most crashes happen close to our homes) will become familiar with the visually confusing speed bumps. There’s other ways to tackle the problem, however. The road could be narrowed — a proven speed reducer — or, similarly, parking permitted on both sides (it’s unclear from the photo whether that’s the case). Different types of pavement treatments could be installed to break up the visual notion of the road as a straightaway. Most ambitiously, the yellow line could be removed. A number of studies have shown that, in the absence of a dividing line, speeds decrease, while distance between opposing traffic streams actually grows. The yellow line is a subtle signal to speed up — one’s territory is “safely” marked. Whether removing the line is more or less “safe” is a relative question; after all, the best safety measure for all involved, drivers and neighborhood residents, would be lower speeds.


Over at Freakonomics, Tom Vanderbilt, author of Traffic: Why We Drive the Way We Do, elaborates on transportation choice architecture.

When signs don’t work:

“Children at play” signs and the like are absolutely ineffective in changing a driver’s behavior, and studies of drivers through school zones show they were driving much faster than they remember. It’s been argued that signs allow us to basically stop thinking, and in certain places experiments have been done in which they’ve been removed, with no negative safety effects.

What behavioral economics tells us about it seems other lanes are always moving faster than ours:

But there’s a curious bias that plays out in oscillating shifts of traffic, observed by the researchers Donald Redelmeier and Robert Tibshirani, in which drivers, who are oriented towards observing things in the forward view much more than the rear, spend more time watching cars passing them than they spend watching themselves passing other cars.

Given the general findings that humans are more sensitive to losses than gains, it doesn’t seem a stretch to imagine that this sense of being passed — of the other lane being faster — would stick out in our brains. All you have to do is pick out a benchmark car in the adjoining lane to see how often we fall for this illusion. I’ve seen these cars pass well out of vision, only to find myself passing them again minutes later. Part of the reason this seesaw effect is happening in the first place is because of all the drivers ahead thought they could get a better deal, and basically ended up just shifting the equilibrium around temporarily.

And what technologies might help improve traffic choice architecture:

One technology that is quite clever and productive is the concept of “variable speed limits,” as seen on highways in England and elsewhere. Basically, if there’s a patch of congestion, it’s detected by sensors, and a new, slower speed limit is announced back “upstream.” That way, rather than having everyone drive at full speed into a traffic jam, which is neither good for safety nor traffic flow itself, the congestion shock wave is “damped.” Of course, people being people, you tend to have to have things like speed limit cameras there to make sure people go the suggested speed.

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