Archive for May, 2009

Traffic Safety Film of the Week

Watching this film — narrated by Jimmy Stewart — I couldn’t help but think all those kids shown in the beginning grew up and moved to Brooklyn, where they now drive the same way. And of course, these kids today would be busily texting in their Ritalin order while driving. These kind of traffic safety programs (or driver indoctrination programs?), whatever their good intentions, have shown to have essentially zero effectiveness, and are thus largely a thing of the past.

Via the superb Prelinger Archives.

Posted on Friday, May 29th, 2009 at 2:31 pm by: Tom Vanderbilt
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Century of Progress

The above chart, which shows the negligible gains in fuel economy cars have seen over the last century (what efficiency gains there were have been plowed into horsepower and more weight), is from “Fuel efficiency of vehicles on US roads: 1923–2006,” by Michael Sivak and Omer Tsimhoni, published in the most recent issue of Energy Policy.

The authors note:

After the 1973 oil embargo, vehicle manufacturers achieved major improvements in the on-road fuel economy of vehicles. However, the slope of the improvement has decreased substantially since 1991. Specifically, from 1973 to 1991, the efficiency of the total fleet of vehicles has improved by 42% (from 11.9 to 16.9 mpg). This represents a compound rate of improvement of 2.0% per year. On the other hand, from 1991 to 2006, the efficiency has improved by only 1.8% (from 16.9 to 17.2 mpg), representing a compound rate of improvement of 0.1% per year.

The curve will begin to look dramatically different by the end of the second Obama administration.

Posted on Friday, May 29th, 2009 at 2:22 pm by: Tom Vanderbilt
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Police: iPhone Left In Hot Car For Three Hours

I somehow missed this classic from The Onion.

According to official police records, two officers forcibly broke into the car at 4:07 p.m. and found the iPhone lying face down on the dashboard. The iPhone at first showed no signs of life, but after a tense few seconds, officers were able to wake it and get it to respond to a series of simple touch commands. Police said that if the iPhone were left in the extreme heat for any longer, it could have died.

Posted on Friday, May 29th, 2009 at 2:08 pm by: Tom Vanderbilt
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The Price of Anarchy

The network optimality problem known as Braess’ Paradox (often confused with the simpler notion of “induced demand”) can be tricky to explain, much less understand (and, like Bigfoot or the Yeti, everyone’s heard of it but we’re not sure anyone’s actually seen it in action, at least purely), but there’s a nice explanation (with illustrations) over at Gravity and Levity.

In his good, though quite technical book Selfish Routing and the Price of Anarchy, Tim Roughgarden also uses a quite entertaining example of a spring and a weight to explain the theory.

Posted on Friday, May 29th, 2009 at 7:51 am by: Tom Vanderbilt
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What About Happy Hour?

An item from the AP notes:

MADISON, Wis. – The Wisconsin Supreme Court says police were within their rights to pull over a drunken driver whose vehicle briefly crossed the center line.

The case involves Michael Popke, who was stopped in 2007 in New London after an officer saw his vehicle briefly drive into the left lane. His blood alcohol content was more than three times the legal limit, and Popke was charged with third-offense drunken driving.

An appeals court had ruled the stop unconstitutional, saying police did not have probable cause to pull him over.

The unanimous Supreme Court overturned that decision Wednesday. Justice Annette Ziegler says the stop was reasonable because Popke was driving erratically at 1:30 a.m.

Does this mean that police do not have probable cause to pull over a driver driving erratically at, say, 1:30 p.m.? What if the police had phoned in the tags, and noted he was a repeat drunk-driving offender — does that represent probable cause, or is that viewed as some kind of “profiling” (e.g., profiling hazardous drivers)?

Posted on Thursday, May 28th, 2009 at 1:58 pm by: Tom Vanderbilt
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Do Smart Cars Breed Resentment?

There’s a curious discussion over on the bulletin boards of the Smart car owners site, oriented around the question of whether the drivers of other cars consider it an insult to be passed by a Smart car. Apparently the phrase “passed by a Smart” is highly Google-able.

Most theories seem to revolve around other drivers not considering the Smart a “real car” — i.e., they take umbrage when the smaller vehicle passes them (masculinity issues or some such), or the site of the small car hurtling along at an “impossible” speed makes them think they themselves must be driving slowly.

When I drove the smart in NYC, I found two general reactions: Versions of the above, and then outright, gushing approval (typically from pedestrians, though, more from other drivers). Sometimes people would seem to be upset that I had passed them, as they would then rev their engine to pass. As a side note, I occasionally witness this on a bike as well — drivers desperate to get ahead of me, even as we approach a red light (but a bike will always win because a car has to begin braking sooner, and because a bike can ride in the space in-between of course), almost as if they were trying to valiantly justify their automotive choice, or reclaim its presumed velocity advantage.

(Horn honk to Rick)

Posted on Thursday, May 28th, 2009 at 9:56 am by: Tom Vanderbilt
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Some Ring Roads Are Bigger Than Others…

Via Strange Maps (via Kottke), an interesting project from Rice University measuring the size of ring roads globally…

Strange Maps writes:

In London Orbital, writer, walker and Londoner Iain Sinclair approaches his favourite subject – his home town – by circumambulating it. The book details his trek along the M25, London’s ring road.

Sinclair completes the 117 mile (188 km) journey in 592 pages, which works out to 5 pages per mile (or 3 per kilometer). As ring roads go, London’s is one of the longer ones – which can with some difficulty be gleaned from this map.

The map layers the peripheral highways of 27 of the world’s larger cities onto a poster, designed by the Rice School of Architecture in Houston, TX. That location is no coincidence, because the poster highlights a record for Houston: it has the largest ring road in the world (or at least the largest of all the world cities surveyed).

However, it is unclear how long a book Mr Sinclair would have to write, were he to transplant his peripatetic procedure (and the same distance-to-volume ratio) from London to Houston.

The city at the centre of the US’s sixth-largest metropolitan area (with 5.7 million inhabitants) has three ring roads: Interstate 610 [circling downtown in a 38-mile (61-km) loop], Beltway 8 [about 83 miles, or 137 km] and the as yet unfinished Grand Parkway [State Highway 99].

Clearly, for Houston to have the world’s longest loop, the big black blob on this map could only be the latter. But a few problems arise. Four, to be exact.

One: the Grand Parkway is far from finished. Only two of 11 segments are completed. However tempting it may be, it is hardly fair to tout something as “the world’s largest” before it’s been completed. Especially since, as any large-scale project, the Grand Parkway has its share of detractors. So it might never get done.

Two: even if it is to be completed, plans may change and length might vary. The website for the Grand Parkway Association doesn’t specify beyond the “circumferential scenic highway” going to be “180+ miles” (app. 290 km) long.

Three: the Houston orbital outsizes all others on this map to such an extent that it’s difficult to imagine its circumference to be no larger than London’s by a factor of 180 to 117.

And finally, four: now that I’m mentioning London’s orbital road again — the website for the UK’s Highway Agency states that the M25 is… the longest ring road in the world.

While the identity of the actual highway(s) surrounding Houston and depicted here remains elusive, it is beyond doubt that the Texan city has a large surface, a fact attested by a map posted earlier on this blog (#327), the discussion of which also touches upon the phenomenon of sprawl (large conurbations with relatively low population density) as a result of increased mobility.

Posted on Thursday, May 28th, 2009 at 8:54 am by: Tom Vanderbilt
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Epidemics, Continued

I earlier ruminated on what might happen to traffic fatalities in the midst of the swine flu epidemic (and noted the vast gulf between the numbers of deaths from both causes).

An answer of sorts has come from Mexico City, from Eric Britton over at World Streets. Via the newspaper Reforma, we learn:

Apparently the swine flu in Mexico City caused few real deaths but many traffic deaths. The large drop in the volume of cars increased velocities and also increased traffic fatalities. There were 12 traffic fatalities in the 6 days before the government issued their swine flu alert and 75 traffic fatalities in the 6 days after.

Here is the kicker: the increase in traffic deaths (63) dwarfs the number of swine flu deaths (8) during those six days.

This is hardly scientific, and I’m dubious increased speeds would be the main reason — I’d guess instead higher exposure from people avoiding public transit — but it is certainly suggestive.

Posted on Thursday, May 28th, 2009 at 8:44 am by: Tom Vanderbilt
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Collateral Damage

Almost in the tragic irony department: London Mayor Boris Johnson (and his Transport Department head), scouting the capital (helmeted) on two wheels for the best cycle routes ahead of next summer’s big “Super Highways” cycling initiative, is nearly taken out by a rogue lorry (which itself had hit a Ford Mondeo, “catapulting” it towards the group). More here and here.

As Ben Porter notes, the event “seems to bring several issues together that are of concern at the moment in London. In addition to the irony of this incident occurring while the cycling group were scouting safe cycle routes there are growing worries about the dangers of HGVs in London, particularly in east London with the increase in construction traffic for the 2012 Olympics. There have been three women killed by lorries in recent weeks in the capital.” (see here and here).

Ben also notes the truck’s doors seem to have flown open after it crossed a speed table at an inappropriate velocity.

(thanks to Karl as well)

Posted on Tuesday, May 26th, 2009 at 4:27 pm by: Tom Vanderbilt
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How to Cover a Car Crash

I’ve got a piece in the current issue of the Columbia Journalism Review discussing the way car crashes are discussed in the media, prompted in part by some recent academic studies on the issue. It’s behind a paywall (it’s a great issue, I’d recommend a purchase), but the magazine has graciously offered to let me post the PDF here for those interested.

Here’s the lead:

The fatal car crash is, unfortunately, an all-too-familiar staple of local journalism. Each of us can summon a grim collage of tragedy: the flashing lights; the fluttering yellow tape on the roadside; the “starburst” windshield; the phrase “he was too young” or “our thoughts and prayers are with the family.”

There is no denying this can make for arresting or poignant viewing or reading. And, unlike sensational reports of deaths that far outweigh their actual occurrence (e.g, in the months leading up to the attacks of 9/11, there was a rash of shark-attack stories, though we were soon to learn that our greatest threat did not come from the sea), the frequency of the coverage seems justified: traffic fatalities are the leading cause of death in the U.S. for people ages one through thirty-four.

But to people who try to reduce the number of crashes, there is often something missing from the picture: Context.”

And the PDF is here.

Posted on Friday, May 22nd, 2009 at 10:41 am by: Tom Vanderbilt
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Just in Time for Memorial Day Weekend

Mikael over at Copenhagenize presents the ultimate tool for “vulnerable road users”: The Motoring helmet!

(careful readers will recall I broach the seemingly outlandish idea of helmets for car drivers in Traffic)

Posted on Thursday, May 21st, 2009 at 10:01 am by: Tom Vanderbilt
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The Revolt of the Masses

This sentence stood out for me in the recent New York magazine profile of Janette Sadik-Khan, NYC’s transpo commissioner, which waved that around that favorite cudgel “elite” to describe the commissioner’s “anti-car” plans — I’m not sure how the wealthier minority who commute daily in NYC’s streets suddenly became the “masses,” and the far greater number of people who walk, take the subway, etc., became the elite.

But perhaps most important, there’s her obsession with the bicycle. Even though cycling is up in the city—levels have doubled since 2000, according to the DOT—most New Yorkers see a bike as a luxury, or don’t have the space to store it, or live and work in places that do not make for a practical commute.

Hmmm. The bike as a luxury? A quick sift of Craigslist would net you a decent ride for $150 — a far cry from the $50,000-plus Escalades the oppressed masses are tooling up Eighth Avenue in, and probably a month’s worth of subway fares (which just went up).

On the “don’t have the space to store it” issue — I don’t get it. Since the issue here is taking away space from cars to give to pedestrians and cyclists, one has the space to store a car (using up some of the world’s most expensive real estate), but not a bike? One car parking space holds how many bikes?

And yes, most New Yorkers do in fact live in a place that has not made for a practical bike commute — New York. Isn’t that the whole impetus behind the commissioner’s vision?

Posted on Thursday, May 21st, 2009 at 9:52 am by: Tom Vanderbilt
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A Quick Thought On Epidemics

The world’s death toll from swine flu? 87 (according to the CDC)

The number of global road fatalities, using WHO’s annual figure of 1.2 million, since the swine flu outbreak was first detected (using a very rough benchmark of a month ago)? 98,630.

And yes, I know the flu could be worse (and still may) if we didn’t take all the measures, do all the reporting, etc.; and that unlike road traffic, flu offers no social/economic benefit.

Of course, a la Donald Redelmeier’s studies on elections and driving fatalities, among other things, one wonders how many traffic fatalities have been prevented by the flu outbreak, in terms of people choosing not to travel (or, have they eschewed public modes in favor of private cars, thus increasing fatalities?)

Posted on Thursday, May 21st, 2009 at 9:26 am by: Tom Vanderbilt
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Traffic Reporting

There’s so much on the intertubes lately, more than I can comment on, but a quick pointer to good stuff you may have already seen:

— Budapest City Hall to consider “artificial traffic jams” in weird test of biking/ped facilities

— The beautiful and terrifying geography we have wrought in the highway interchange.

— Ryan Avent on fuel-economy standards.

— New York drivers “worst in nation,” typically media-friendly, absolutely unscientific “study” finds

Texting driver hits cop.

Utica, N.Y., getting rid of surplus traffic lights (“These lights were needed when the city had a population of 100,000. Now there are about 60,000 people living here and the lights will come down in stages.”)

Posted on Thursday, May 21st, 2009 at 9:13 am by: Tom Vanderbilt
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The Highway Supply Chain

I’ve been intrigued by the comparisons made to highway traffic behavior and supply chains (see Carlos Daganzo, et al., on the “bullwhip effect”).

A recent article in the Wall Street Journal, on hiccups in supply chains caused by recent economic turmoil, contained a number of implicit, if unstated, comparisons to highway traffic.

The recession has exposed a harsh side effect of the supply-chain system. Because modern industry rewards suppliers with the leanest inventories and fastest reaction times, when economic crisis struck, tech companies up and down the line contracted as sharply as possible in hopes of being the ones to survive.

Forced to guess at demand for their products in a plummeting market, everyone hit the brakes, hard. An examination of the electronics supply chain — from retailers all the way back to makers of factory machinery — shows that, at almost every stage, companies were flying blind as they cut.

The parallel here is a group of cars traveling at high speeds, and close following distances, on the highway — an inherently unstable regime. If one car hits the brakes, the succeeding car, not fully aware from the weak signal how much the vehicle ahead is actually braking (or, for example, if a car’s view of the traffic ahead is blocked by an SUV — for we often make our braking decisions by what drivers further up the chain are doing — the car driver’s “clarity” of the highway supply-chain ahead has been reduced), also hits the brakes — perhaps more than necessary — which amplifies up the chain, often in an erratic fashion. One driver’s underreaction may even penalize another driver six or seven cars up the chain.

And so it is with supply chains:

In March, Best Buy Co. said it could have sold more electronics equipment in the three months ended Feb. 28, but its suppliers’ deep cuts made it tough to keep shelves stocked. Suppliers “all decided to build a lot less,” says Best Buy merchandizing chief Michael Vitelli.

As the contraction raced down the supply chain, its effects became amplified. Rick Tsai, CEO of chip manufacturer Taiwan Semiconductor Manufacturing Co., has said that, in last year’s final quarter, consumer purchases of electronics gear in the U.S. fell 8% from the prior year. But product shipments fell 10%, and shipments of the chips that go into the gear dropped 20%.

Everyone “braked” more than they had to, thus consuming in essence Best Buy’s travel potential.

There was another interesting parallel, in light of a potential economic recovery, and an opening of the supply-chain spigot.

Still, “It’s easier to turn the switch off than turn it back on,” says David Pederson, Zoran’s vice president of corporate marketing.

This has its highway equivalent in the fact, as noted by Dirk Helbing and others, that it takes longer to emerge from a congested state than it does to enter one.

Posted on Thursday, May 21st, 2009 at 8:47 am by: Tom Vanderbilt
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Sounds Electric

Many years ago, when I was living in Spain, I traveled by train to Basel, Switzerland. In Spain my ears had gradually become accustomed to the sounds of Iberian urbanity — the one that always registered foremost was the toxic whine (and acrid whiff) of cheap motos, clattering off the narrow streets. Stepping out onto the streets of Basel (on a Sunday, no less), I was almost overwhelmed by the stillness. So much so that, as I wandered about in a near fugue state, I was almost struck by one of the city’s trams. But it sounded a polite bell to alert me to its presence, and I survived Switzerland.

I thought of the episode when reading Dan Hill’s brilliant exposition on a recent Economist article on the idea that electric/hybrid cars like the Toyota Prius, which of course make much less noise than traditional cars, represent a grave threat to urban safety, and that traditional (loud) car noise will have to be retro-fitted back into the car. I had always thought the car of the future, as depicted in sci-fi and the like, would proceed past with nothing more than a soft whoosh, but one wonders: Is this is a real issue?

Hill writes:

Let’s quickly deal with the safety issue first. People will adapt easily enough. We’ve adapted to numerous successive modes of transport in the past without the need to artificially increase the noise that mode of transport generates (though the first automobiles required a man with a flag walking in front of them. Is this not the aural equivalent of that, and so equally likely to fade away?)

One of the numerous reasons why bicycles are a more civic mode of transport is that they do not make much noise. Even at the speeds cyclists can get up to, this near-silent mode is apparently still safe enough not to warrant a pedal-powered drone, say. A bell suffices, and after that it’s about taking due care and attention on both sides. As bikes slowly become the dominant mode of personal transport in cities, this shouldn’t change. Cyclists, a few idiots aside, have to rely on individual responsibility to a greater extent than motorists, partly due to their relative fragility. This is not a bad thing necessarily – it forms a thin undulating layer of civic substrate.

Of all the possible threats cars pose to pedestrians in cities, lack of noise seems an odd crusade for the Economist to get behind — why not the speed of cars (which is a de facto explanation in all urban pedestrian fatalities), the provision of pedestrian facilities (a key reason behind literally hundreds of thousands of pedestrian fatalities in a country like India), visibility in car design (some current models have a dreadful range of sight), the weak legal penalties for striking a pedestrian, etc. etc.

We also need more than anecdotal evidence that Priuses are causing more pedestrian fatalities than other cars (see the comments in this website for an interesting discussion; and if anyone has any real data, please advise); I might imagine there would be a statistical artifact here even if there were slightly more Priuses involved in pedestrian fatalities — i.e., Prius’ market share is higher in places where there are more pedestrians. And as Hill notes, there are certainly more effective pedestrian safety strategies — ones that would benefit blind and well as sighted pedestrians — than ratcheting up noise; Volvo’s CitySafety for one. Not to mention there are already plenty of pedestrians who don’t hear my normal-sounding car because they’re wrapped up in an iPod or on the phone.

Traffic noise, or at least excessive traffic noise, after all, is a detriment to the quality of life — shown in everything from real estate values to people’s stress responses to noisy intersections (the work of Christian Nold, for example) to the negative environmental impacts (the work of Richard Foreman) — why on Earth would we want to artificially raise it, when there were other options available?

Hill’s piece goes on to consider a number of interwoven strands of cars, sound, and urban life, and he taps a wonderful passage about the horn in New Delhi from Geoff Dyers’ new novel Geoff in Venice:

“The din of horns rendered use of the horn simultaneously superfluous and essential. The streets were narrow, potholed, trenched, gashed. There was no pavement, no right of way – no wrong of way – and, naturally, no stopping. The flow was so dense that we were rarely more than an inch from whatever was in front, beside or behind. But we never stopped. Not for a moment. We kept nudging and bustling and bumping our way forward. Given the slightest chance – a yard! – Sanjay went for it. What, in London, would have constituted a near-miss was an opportunity to acknowledge the courtesy of a fellow road-user. There were no such opportunities, of course, and the idea of courtesy made no sense for the simple reason that nothing made any sense except the relentless need to keep going. From the airport to the hotel, Sanjay had used the horn excessively; now that we were in the city proper, instead of using it repeatedly, he kept it going all the time. So did everyone else. Unlike everything else, this did make sense. Why take your hand off the horn when, a split-second later, you’d have to put it back on?”

New Delhi, an incredibly noisy city, is hardly a paradise of pedestrian safety. Pinning pedestrian safety to car noise sounds a bit suspicious to me.

Posted on Thursday, May 21st, 2009 at 8:18 am by: Tom Vanderbilt
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Changing Ends at Half Time

Absorbing some of the recent debate over the new fuel efficiency standards, not to mention the hovering controversy over congestion or VMT pricing — or even the closing of segments of Broadway to car traffic in NYC — I was reminded of a passage I recently came across in a lecture by Phil Goodwin, now emeritus professor at University College London, back in 1997:

I think we are engaged in one of those historic transitions which looks quite different when you are in the middle of it, from what it looks like in retrospect – a bit like the great liberal reforms of the 19th century. The abolition of slavery, and of child labour; the introduction of free, compulsory education; the concept of public health; the construction of a system of drains; running clean water; the right to vote. All of these, at the time, seemed revolutionary, or threatening, or infringements on the liberty of the citizen; or too expensive, and there were long arguments. In retrospect, they seem logical, fair, efficient, and absolutely good value for money. Subsequent generations even wonder why it took so long, and why there was so much fuss about it.

I see transport as similar. Mass car ownership offered us a control over time and space which no previous generation has ever had, and we took it up willingly and enthusiastically. But it has got out of hand. It has now started to defeat its own advantages. There is much talk of a ‘level playing field’ – but playing fields are never level, which is why we change ends at half time. It’s now half time – literally: we are probably about half way to the levels of traffic that would eventually apply if trends continue unchecked, and that just won’t do. So we need to find a better way, or better ways.

It may all seem very complicated just at the moment. But we do our children no favours if we confine them to a car-dependent mobility. And I think our grandchildren will wonder what took us so long.

Posted on Thursday, May 21st, 2009 at 7:30 am by: Tom Vanderbilt
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‘a hieroglyphic sense of concealed meaning’

Slightly tangential here, but I couldn’t resist this image, via Space and Culture, of what, at first glance, resembles the kind of aerial landscape one sees upon immediately departing Newark’s Liberty Airport but is actually a “tapestry made out of old motherboards”

It reminded me of something that Kazys recently reminded me of, which is the following reference in Thomas Pynchon’s novel The Crying of Lot 49:

“She thought of the time she’d opened a transistor radio to replace a battery and seen her first printed circuit. The ordered swirl of houses and streets, from this high angle, sprang at her now with the same unexpected, astonishing clarity as the circuit card had … There were to both outward patterns a hieroglyphic sense of concealed meaning, of an intent to communicate. There’d seemed no limit to what the printed circuit could have told her (if she had tried to find out); so in her first minute of San Narciso, a revelation also trembled just past the threshold of her understanding.”

Posted on Wednesday, May 20th, 2009 at 11:22 am by: Tom Vanderbilt
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The Sense of Being Stared At (in the car)

As we’re on the topic of curious psychological effects, have you ever, as a passenger in a car, stared to the side, at a driver in the neighboring lane, and suddenly had them turn to face you?

This is a game I sometimes play when bored in the back of a taxi, and it can be quite disconcerting. I have often wondered: Am I simply remembering with greater frequency and fidelity those times when somebody actually looked back, and forgetting all the times they didn’t, invoking a sort of memory bias (e.g., because I think that people stare back I am primed to remember the times they actually do)?

The rogue psychologist Rupert Sheldrake has explored the “eyes in the back of the head” phenomenon (or what he calls the “non-visual detection of vision”) in his book The Sense of Being Stared At, which has occasioned a good amount of critical commentary. But, as Sheldrake has noted, the feeling that this sense exists is quite strong:

Most people have had the experience of turning round feeling that someone is looking at them from behind, and finding that this is the case. Most people have also had the converse experience. They can sometimes make people turn around by staring at them. In surveys in Europe and North America, between 70% and 97% of the people questioned said they had had personal experiences of these kinds (Braud et al., 1990; Sheldrake, 1994; Cottrell et al., 1996).

When I do in this car, of course, I am more properly considered to be alongside the other person, or just behind, so it’s perhaps not as much as a “non-visual” detection as a peripheral detection. But still, it seems quite powerful — what would make someone take their eyes off the road and return my glance? (another proviso here is that they may simply have been turning to look at my car, out of idle curiosity). Is it some primitive apparatus for detecting hazards? Is it that incredibly powerful ability we humans have (and which the non-human primates do not) to detect, and make, eye contact?

What’s interesting too is what happens once that driver in the other lane meets my eyes. Often, they look a bit startled, or uncomfortable, and I myself try to look away, having been uncomfortably caught out. This too has been examined by psychologists, as this piece in Scientific American notes:

In one version of the experiment, the research assistant pulled up in his motor scooter next to a car waiting at a red light and stared expressionlessly at the driver until the light turned green. In another version, the research assistant stood on the street corner, turned to face an approaching pedestrian, and again stared expressionlessly at this person’s face for an uncomfortable length of time.

As predicted, being stared at prompted people to ‘flee’ measurably faster than not being stared at. In the case of the motor scooter, car drivers who were in the staring condition stepped on the gas pedal harder when the light turned green than those in the control condition, as measured by the length of time it took them to cross the intersection. Likewise, pedestrians who were stared at also picked up their step.

In any case, I’m curious to hear from readers: Do you ever notice this effect? Are there any other explanations I’ve left out?

Posted on Wednesday, May 20th, 2009 at 10:48 am by: Tom Vanderbilt
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Warning: Zeignarnik Effect Ahead

Reading Roadguy’s account (I’ve got the Twin Cities on my mind, I guess) of his trip to this year’s American Planning Association meeting, I was intrigued by his description of a panel on “digital billboards.”

Roadguy noted a delicious sort of Catch-22 during the talk: “Fellow panelist Marya Morris, a Chicago-area consultant, pointed out the conundrum that owners of digital signs face: They argue that the signs aren’t distracting while simultaneously telling advertisers that such billboards “can’t be ignored.”

I’ve not yet seen a good, peer-reviewed study on the safety (or lack thereof) of digital billboards (and if anyone has, please advise). Anything from the industry must be viewed as suspect (guess what: they’re safe!), and a controlled, before-and-after study of a highway section where a billboard has been added would be a tricky proposition (unless it became an immediately apparently crash hotspot). One study I’d like to see done, just of out curiosity, would be to gather loop data near the billboards: Do they have a deleterious effect on traffic flow itself?

Roadguy noted something else of interest: “Morris and Baker both spoke about the Zeignarnik effect, a psychological compulsion to focus on a task not yet completed, and how it causes drivers to look at digital signs repeatedly. Baker cited a billboard in Cedar Rapids, Iowa, as particularly perilous: it displays multi-part riddles.”

Not having had any psychology as an undergrad, this Zeigarnik effect was new to me, but as I love a good effect (who doesn’t?), I cast a cursory Google-glance over at 43folders and found this delightful account:

“While sitting in a restaurant in Vienna—every good story about a psychologist takes place in Vienna—Bluma Zeigarnik noticed that a waiter could remember a seemingly endless number of items that had been ordered by his customers. However, once he had delivered the orders to the waiting diners, he no longer remembered what he had just served….

Though Zeigarnik didn’t get her coffee cup refilled following her meal, she did get into the annals of psychology. Zeigarnik theorized that an incomplete task or unfinished business creates “psychic tension” within us. This tension acts as a motivator to drive us toward completing the task or finishing the business. In Gestalt terms, we are motivated to seek “closure…”

The implication is that people remember incomplete processes more more than those that are completed.

I’m no brain expert or psychologist, but I wonder if the waiter was simply storing those orders in short-term memory, and, having concluded they were no longer of importance, was not encoding them to longer-term memory (and just how many orders could a waiter remember, echoes of that “seven-digit” effect of short-term memory).

And I can also imagine this this effect might be served up by marketers as a bit of psychological juju to help sell their product: As opposed to a static billboard, whose message one would instantly absorb and then discard (as with one’s memory of traffic signs they’ve passed), some sort of narrative-in-progress might leave the driver/viewer hungry for a kind of resolution, “wanting more,” and thus dwelling more on the subject than they might have. But again, it’s hard to argue that the same stickiness that’s good for marketing would be good for driving.

Posted on Wednesday, May 20th, 2009 at 10:24 am by: Tom Vanderbilt
Comments Off on Warning: Zeignarnik Effect Ahead. Click here to leave a comment.
Traffic Tom Vanderbilt

How We Drive is the companion blog to Tom Vanderbilt’s New York Times bestselling book, Traffic: Why We Drive the Way We Do (and What It Says About Us), published by Alfred A. Knopf in the U.S. and Canada, Penguin in the U.K, and in languages other than English by a number of other fine publishers worldwide.

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Upcoming Talks

April 9, 2008.
California Office of Traffic Safety Summit
San Francisco, CA.

May 19, 2009
University of Minnesota Center for Transportation Studies
Bloomington, MN

June 23, 2009
Driving Assessment 2009
Big Sky, Montana

June 26, 2009
PRI World Congress
Rotterdam, The Netherlands

June 27, 2009
Day of Architecture
Utrecht, The Netherlands

July 13, 2009
Association of Transportation Safety Information Professionals (ATSIP)
Phoenix, AZ.

August 12-14
Texas Department of Transportation “Save a Life Summit”
San Antonio, Texas

September 2, 2009
Governors Highway Safety Association Annual Meeting
Savannah, Georgia

September 11, 2009
Oregon Transportation Summit
Portland, Oregon

October 8
Honda R&D Americas
Raymond, Ohio

October 10-11
INFORMS Roundtable
San Diego, CA

October 21, 2009
California State University-San Bernardino, Leonard Transportation Center
San Bernardino, CA

November 5
Southern New England Planning Association Planning Conference
Uncasville, Connecticut

January 6
Texas Transportation Forum
Austin, TX

January 19
Yale University
(with Donald Shoup; details to come)

Monday, February 22
Yale University School of Architecture
Eero Saarinen Lecture

Friday, March 19
University of Delaware
Delaware Center for Transportation

April 5-7
University of Utah
Salt Lake City
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April 19
International Bridge, Tunnel and Turnpike Association (Organization Management Workshop)
Austin, Texas

Monday, April 26
Edmonton Traffic Safety Conference
Edmonton, Canada

Monday, June 7
Canadian Association of Road Safety Professionals
Niagara Falls, Ontario

Wednesday, July 6
Fondo de Prevención Vial
Bogotá, Colombia

Tuesday, August 31
Royal Automobile Club
Perth, Australia

Wednesday, September 1
Australasian Road Safety Conference
Canberra, Australia

Wednesday, September 22

Wisconsin Department of Transportation’s
Traffic Incident Management Enhancement Program
Statewide Conference
Wisconsin Dells, WI

Wednesday, October 20
Rutgers University
Center for Advanced Infrastructure and Transportation
Piscataway, NJ

Tuesday, March 8, 2011
Ontario Injury Prevention Resource Centre
Injury Prevention Forum

Monday, May 2
Idaho Public Driver Education Conference
Boise, Idaho

Tuesday, June 2, 2011
California Association of Cities
Costa Mesa, California

Sunday, August 21, 2011
American Association of Motor Vehicle Administrators
Milwaukee, Wisconsin

Wednesday, October 26, 2011
Attitudes: Iniciativa Social de Audi
Madrid, Spain

April 16, 2012
Institute for Sensible Transport Seminar
Gardens Theatre, QUT
Brisbane, Australia

April 17, 2012
Institute for Sensible Transport Seminar
Centennial Plaza, Sydney
Sydney, Australia

April 19, 2012
Institute for Sensible Transport Seminar
Melbourne Town Hall
Melbourne, Australia

January 30, 2013
University of Minnesota City Engineers Association Meeting
Minneapolis, MN

January 31, 2013
Metropolis and Mobile Life
School of Architecture, University of Toronto

February 22, 2013
ISL Engineering
Edmonton, Canada

March 1, 2013
Australian Road Summit
Melbourne, Australia

May 8, 2013
New York State Association of
Transportation Engineers
Rochester, NY

August 18, 2013 “Ingenuity” Conference
San Francisco, CA

September 26, 2013
TransComm 2013
(Meeting of American Association
of State Highway and Transportation
Officials’ Subcommittee on Transportation
Grand Rapids MI



May 2009

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