Over at Freakonomics, Steven Dubner wonders about the ethics of dimming headlights in the face of oncoming traffic (e.g., why do drivers perform this everyday altruism in the face of seemingly small consequences for not doing so). He also asks: “What I’d like to know is whether the benefit of dimming your headlights — that is, the benefit of not blinding the oncoming driver — is indeed larger than the benefit of keeping your own brights burning?”
This is a question that people who study vision and lighting and driving have thought about a lot. To summarize a conversation I had with Michael Sivak, at UM-TRI, there’s three distances involved here: The legally required distance to dim one’s lights in the face of oncoming vehicles, the optimal distance for maintaining one’s own visibility (and, I suppose, not blinding the other), and then what drivers’ actually do. Readers of this blog will suspect the last factor does not often match up with the two previous factors (and, I should add, as with many things in driving, the scientific issues around night-time illumination are much more complex than the “average expert driver” — i.e., everyone — realizes).
From a pure visibility point of view, opposing drivers should never dim their lights, but should drive on high beam through the whole meeting process. There are, however, certainly other reasons for dimming the lights, such as discomfort glare and fatigue over a longer period with repeated high-beam meetings.
The study of Helmers and Rumar (1975) indicates that the improvements in the low beam since the fifties and sixties have been considerable. That is probably the main reason why the high-beam visibility curve and the low-beam visibility curve in later studies do cross each other—at least when the intensity differences between the two opposing high beams are not too large (about triple or less).
When the two opposing high beams differ substantially in intensity, the visibility differences between the two opposing drivers are quite pronounced (see Figure 3). In such situations, it is most probable that the driver with the weaker high beams will be the one who wants to initiate the dimming, because the driver with the weaker high beam experiences substantial disability and discomfort glare. On a straight, flat road, such a driver will want to dim the high beams at a very large distance between the vehicles.
An early dimming means that both drivers will have to drive on low beams for an extensive part of the meeting process. However, as stated above and illustrated in Figures 2 and 3, at larger separations low beams normally offer shorter visibility distances than high beams. This means that an early dimming leads to short visibility distances for a greater distance traveled, for both opposing drivers.
From a new traffic-themed issue of Philosophical Transactions of the Royal Society, I was particularly interested in an article by Mark Campbell, et al., “Autonomous driving in urban environments: approaches, lessons and challenges.” As I discuss vis a vis Stanford’s “Junior” in Traffic, the perceptual and interaction dynamics of autonomous driving are infinitely complex. Here’s one bit, which follows a case study in which a vehicle had executed a maneuver that, while not being against the safety rules per se, were “still undesirable” — because, in essence, the vehicle, despite being equipped with formal Bayesian estimators and the like, had failed to take into account for what other vehicles might due. In other words, how do you program a vehicle to “expect the unexpected”?
In order for autonomous driving to reach its full potential, it is vitally important that the cars cooperate in the sense that they agree on traffic rules, whose turn it is to drive through an intersection, and so forth. For this, robust agreement protocols must be developed. Recent work on how to make multiple vehicles agree on common state variables, e.g. using consensus or gossip algorithm (Boyd et al. 2006; Olfati-Saber et al. 2007), provides a promising starting point for this undertaking.
When running such agreement algorithms, it is conceivable that not all vehicles will cooperate. They may, for example, be faulty, or simply driven by human operators, and such vehicles must be identified and isolated in order to balance autonomy with human inputs. This will be true on individual cars, but even more so in mixed human–robot networks. Questions of particular importance (that will have to be resolved using the available interconnections) include the following. (i) Safety: autonomous cars must be able to identify human-driven cars and then not drive into them even though they may violate the robot driving protocol. (ii) Opportunism on behalf of the human drivers: people are already driving badly on the road when the other cars are driven by people. How will they act if no-one is driving? This needs to be taken into account by the autonomous cars (i.e. not only will people not follow the ‘correct’ protocol—they might be outright hostile). (iii) Collaborative versus non-collaborative driving: how should non-cooperative vehicles be handled in an algorithmically safe yet equitable manner?
Igor Sikorsky was nothing if not optimistic about the idea of a personal helicopter for everyone (an idea that should now send any reasonable person to the brink of terror) in this 1942 article in The Atlantic.
A question certain to trouble you is this: With hundreds of thousands, perhaps millions, of helicopters flying in all directions at once, what about sky congestion and air traffic problems?
This problem has been foreseen and already a certain amount of planning has been done. While air traffic problems will not be at all comparable to what we now have with the motorcar, there must certainly be one-way air lanes within the limits and in the neighborhood of big centers of population. There will be “slow” and “fast” altitudes and you will choose the one that suits your temperament. Naturally, all helicopter highways will be at a safe distance from the airplane levels.
All helicopters, of course, will remain at a reasonable altitude over thickly populated centers. But there need be no such “flight plan ” as airplanes now must often submit to before undertaking a long journey. Helicopter owners will fly at will, bound only by their common sense and some general traffic rules which are easily obeyed in the vast reaches of the sky.
Nor will the strict physical examination that now might prohibit many thousands from flying an airplane be necessary. A person who can drive an automobile can fly a helicopter; and a man or woman with middle-aged reflexes is just as safe in one as in the other because the helicopter, as a rule, is always moving slowly when close to the ground. The helicopter owner will have to pass no stricter examination than is—or should be—necessary for driving a motorcar. He should not be color-blind, his vision should be normal with or without glasses. A man or woman with a heart ailment should not drive a helicopter—nor an automobile.
Bill Beaty, the amateur “traffic waves” scientist described in Traffic, writes in to describe his early experiences with Seattle’s new Active Traffic Management System — the “dynamic” system of varying speeds, imported from Europe, which is meant to ameliorate the impact of drivers driving into vast stop-and-go traffic (with the ensuing shockwaves).
Beaty was curious to note that the first part of the project is happening on the very section of I-5 where he first began developing his one-man crusade for traffic harmonization. Here’s how he describes his new commute, which seems to have some of the disequilibrium that new schemes bring:
In the first week it created very strange patterns: huge I-5 jams on
Sunday (when Sunday I-5 northbound has always been empty.) They now seem
to be tweaking their algorithm. Or perhaps drivers are no longer freaking
out. Patterns are still odd, but keep changing over many days.
From what I can see, they’re trying to limit the inflow to the daily
northbound jam at I-5 and I-90 interchange. The result is a large
slowdown far south of the city, with an empty region right at the location
of the daily jam. Very odd to encounter a major slowdown near my own home,
where there never was congestion before …but then at the usual location
of the giant I-5 snarl, the traffic flows free at 50mph. Presumably there
no longer exists any continuously-growing daily jam. Merging at city
exits has suddenly become easy. Probably the old jam has been converted
into shockwaves moving slowly backwards, rather than the previously huge
region of 20mph driving.
Another ATMS section is on I-520 …which is right where I first saw the
string of headlights that inspired my first online article. Bizarre
coincidences. Or maybe the bigwigs in the Seattle traffic control
community have all been reading my site?
Any other Seattle-area readers/engineers care to share their experience?
And speaking of commute times, Harry Kao writes in to tell me he has created a Google Maps visualization based on the bit in my book about the historical constancy (in some cases) of commute times. You can find it here (click on the map to engage).
And here are the details, which Kao notes need refining (and I wonder how this differs from WalkScore’s new “Commute” tab). Perhaps someone out there can help?
The primary data source is the CTPP 2000. This survey was sent to a subset of households during the 2000 Census and records, among other things, where people live and work.
The CTPP has since been superseded by the ACS. Although transit statistics from the ACS have been published more recently, the the new data is not sufficiently fine-grained for use with this map.
The CTPP provides data on a census tract level. However, this map uses zip codes to identify regions because they’re more familiar to most people. The mapping from census tract to zip code is done by using the Census Zip Code Tabulation Areas (ZCTAs) to determine the proportion of each census tract that falls within each zip code and weighting the CTPP data accordingly.
The Google Maps API is used to determine routes and transit times. The usual caveats apply. In particular, it is assumed that all commuters drive during non-peak hours. This is surely incorrect (but it’s the best that I can do) so the trip times are likely to be underestimates.
People looking into the effects of long commutes have found everything from higher stress levels to fewer social relationships, but a new study by Jos N. van Ommerenlow and Eva Gutiérrez-i-Puigarnaua, published in Regional Science and Urban Economics, throws another factor into the mix: The tendency for employees to show up for work.
Our results indicate that, ceteris paribus, commuting distance has a strong positive effect on absenteeism, with an elasticity of about 0.07 to 0.09. In the hypothetical case that all workers in the economy have a negligible commute, absenteeism would be about 15 to 20% lower, roughly one day per year, so the results are economically relevant. Our favoured interpretation is that the effect identified is predominantly through an effect of the time component of commuting costs on voluntary absenteeism in line with Ross and Zenou, 2008 (S.L. Ross and Y. Zenou, “Are shirking and leisure substitutable? An empirical test of efficiency wages based on urban economics theory,” Regional Science and Urban Economics 38 (5) (2008)), but we cannot completely exclude the possibility that some of the effect is through an effect on health and therefore on involuntary absenteeism, as argued by Zenou (2002).
Reading the various stories recently about driving on beaches, as vexing for safety reasons as environmental and simple quality of life factors, I couldn’t help but think back to Edward Abbey’s classic reproach, in Desert Solitaire, to those tourists who traveled via car in the national park at which he was stationed. I know Abbey the man is something of a thorny subject but the book is one of those rare titles that leaves an incendiary impression, the date and place of first reading forever fixed in one’s mind.
What can I tell them? Sealed in their metallic shells like mollusks on wheels, how can I pry the people free? The auto as tin can, the park ranger as opener. Look here, I want to say, for godsake folks get out of them there machines, take off those fucking sunglasses and unpeel both eyeballs, look around; throw away those goddamned idiotic cameras! For chrissake folks what is this life if full of care we have no time to stand and stare? Take off your shoes for a while, unzip your fly, piss hearty, dig your toes in the hot sand, feel that raw and rugged earth, split a couple of big toenails, draw blood! Why not? Jesus Christ, lady, roll that window down! You can’t see the desert if you can’t smell it! Dusty! Of course it’s dusty – this is Utah! But it’s good dust, good red Utahn dust, rich in iron, rich in irony. Turn that motor off. Get out of that piece of iron and stretch your varicose veins, take off your brassiere and get some hot sun on your old wrinkled dugs! You sir, squinting at the map with your radiator boiling over and your fuel pump vapor-locked, crawl out of that shiny hunk of GM junk and take a walk – yes, leave the old lady and those squawling brats behind for a while, turn your back on them and take a long quiet walk straight into the canyons, get lost for a while, come back when you damn well feel like it, it’ll do you and her and them a world of good. Give the kids a break too, let them out of the car, let them go scrambling over the rocks hunting for rattlesnakes and scorpions and anthills – yes sir, let them out, turn them loose; how dare you imprison little children in your goddamned upholstered horseless hearse? Yes sir, yes madam, I entreat you, get out of those motorized wheelchairs, get off your foam rubber backsides, stand up straight like men! like women! like human beings! and walk – walk – WALK upon our sweet and blessed land!
A colleague sends the above photo of a “double roundabout,” in Buffalo, NY (or it’s suburbs). While your first thought might be, wow, how confusing, consider the Google Map image below that shows the original intersection — too big, actually two intersections masquerading as one (one can imagine cars getting “trapped” in that little extra segment, and box-blocking problems). Undoubtedly there was a crash problem, hence the double roundabout. Which are used in the U.K. (and taken to its logical extension in the “Magic Roundabout”, of course, but are, as far as I know, relatively novel here. Anyone live near here by chance and care to weigh in?
An interesting prototype design via the PFSK Conference for an “ergonomic” crosswalk that takes into account pedestrians’ natural inclinations to want to shorten the distance it takes them to cross the street (as someone once told me, ‘pedestrians are natural Pythagoreans’). I can foresee a problem with cars, who already stray into the crosswalk, having a bit of a problem lining up. And while I like the red/yellow LED light concept in theory, does it just lessen our tendency to look at the actual environment for safety cues?
It seems that James Cameron doesn’t have a lock on innovative 3-D imagery: As the Globe and Mail reports:
Motorists travelling on 22nd Street in West Vancouver will be confronted with a 3D image of a little girl chasing a ball in the street starting next Tuesday. The girl will be an optical illusion, but the scenario is very real, according to David Dunne of the BCAA Traffic Safety Foundation.
I’m all for illusion-based traffic calming techniques that create the sensation that drivers are driving faster than they really are — and I realize there is no greater challenge in traffic engineering than managing driver speed — but I would have reservations about putting an imaginary obstacle in the middle of the road (perhaps putting the child on the side of the road would be merely enough?). For one, it may, however unlikely, provoke the driver into taking evasive action, thus getting into real trouble. For another, the presence of false hazards may reduce our vigilance to real hazards. And one wonders if this would open the door to 3-D billboards and other projections.
But what do readers think?
(horn honk to David Levinson)
What better way to conclude the Australasian Road Safety Conference, thought me, then to head out for a spot of cycling in Canberra, where spring is just on the wing. My guide was Ashley Carruthers, an anthropologist and member of local advocacy group Pedal Power (and my ride was a surprisingly nimble fold-up Dahon). Canberra is one of those intensely planned capital cities, its geography dictated by fiat and compromise, its layout and design (via the American Walter Burley Griffin) evoking, to my mind, D.C. — though, as Carruthers noted, reputedly infused with esoteric and hieroglyphic meanings. While the city, cycling wise, hasn’t gotten the attention of, say, Melbourne, with its new sharing scheme, Pedal Power boasts a large and active membership, and there’s a fairly wide trail network (though not much evidence of on-street cycling, in the area I was staying, at least).
Now, about that magpie, which I had tweeted about briefly in reference to its intoxicating song. It turns out they can be rather fierce enemies of those on bikes, swooping down from trees to land on their helmets and peck at their ears. As a countermeasure, riders will strap plastic twist-tie-like things to their helmets, virtually sprouting of their heads like gangly antennae. It was a bit unnerving to find a couple of these fellows coming toward me, the shock troops of some alien two-wheeled race. I’m not sure if this sort of thing happens elsewhere, but it was the first I had seen in such active preparation for avian attack. Yesterday, at least, the magpies were quiet.
Jon Stewart talking to Drew Barrymore:
JS: To me, the hallmark of civilization, and I believe this on its core foundational level, is the every-other-car merge at tunnels…
DB: Well, they don’t let you anymore, they have cones that say, like, don’t you dare.
JS: No, no, when you get up to that, and it’s like four cars, and it goes down to one. And everybody suddenly, no matter what, Jew, Muslim, gay, straight, black, white, it doesn’t matter, everybody just goes, ‘I’m next,’ ‘No, you’re next,’ ‘Please,’ and it’s like the zipper merge, and it really says, to me, this is why we don’t drink the same water we shit in anymore, because we are a civilized society. That’s my theory.
JS: Who the hell knows.
DB: I love you.
Just a quick note to point to this profile of Donald Redelmeier, who appears in Traffic, posted in the New York Times.
Sheer brilliance in the ending:
The idea came to him one day in a hallway at the University of Toronto’s Faculty of Medicine, where he had stopped to admire a century’s worth of class photos showing mostly white men.
“Some people might say, ‘What an old boys’ network,’ ” Dr. Redelmeier said. “But I thought, ‘My goodness, what a homogeneous population, akin to identical white mice, which thereby controls for all sorts of differences.’ ” Thus was born another Redelmeier classic.
Via The Register, a VW designer talks about self-driving cars:
Huhnke said that his group wanted to find out if drivers passengers in autonomous cars would feel safe: “If you have an autonomous car driving … do you trust your car? Do you really press the autopilot button and let the car drive you at 60 miles per hour?” So they conducted a study — and were surprised by the results.
“We created a car with a second steering wheel in the rear where the driver couldn’t see it,” he told his audience. “He or she pressed the autopilot button and thought the machine would really drive without human help. Someone drove in the rear seat without being recognized by her or him. Well, you couldn’t imagine: after a few seconds, they already took the newspaper and read the news articles. So they trusted already the machine, which was great.”
Huhnke’s group then pushed its luck: “We also initialized some emergency situations: ‘So please, go back to your steering wheel and take over, we need some help from you,’ and they did it. They put the newspaper back, and just controlled the car through the situation. Then what did they do? Immediately press the button and start it again — it was really amazing.”
The question, of course, from a human factors point of view, is how quickly the car can alert drivers to a particular emergency (and what the warning will be; either a vague “emergency” or the exact diagnosis), and how quickly they can respond (and whether it’s the correct response) after they’ve been “out of the loop.” Would a texting driver with eyes and mind off-road be able to respond to a path intrusion warning that comes just as the car detects it?
I’ve been traveling a lot the last week (currently doing the “milk run” to Australia), hence the lack of updates here, but here’s a few of the myriad things that have come across the transom (apart from those I’ve posted on Twitter):
A reminder of my own piece on Slate about London Transport posters.
A “safer” way to text and drive (as a thought exercise try replacing the word “texting” with drinking as you listen to this).
Endlessly hypnotic: Bicycle rush hour in Copenhagen.
Adam Greenfield ponders the complexity of bus networks. (“You know I believe that cities are connection machines, networks of potential subject to Metcalfe’s law. What this means in the abstract is that the total value of an urban network rises as the square of the number of nodes connected to it. What this means in human terms is that a situation in which people are too intimidated to ride the bus (or walk down the street, or leave the apartment) is a sorrow compounded. Again: everything they could offer the network that is the city is lost. And everything we take for granted about the possibilities and promise of great urban places is foreclosed to them.)
How about an “ignition interlock” for habitual speeders in Australia?
The always good Carl Bialik on “traffic math.” (and I liked this bit: Nicholas Taylor, a research fellow at the consulting company Transport Research Laboratory in Wokingham, England, says that adding road capacity can be effective if it isn’t perceived as adding capacity. Opening a highway’s shoulder to traffic during peak hours appears to work, Mr. Taylor says, because it is “not seen as a whole new provision of the road. There’s a psychological element to it.”)
A number of people have written in, or tweeted (and don’t forget to find me in the tweetosphere), to tell me about a traffic jam in China, currently in its ninth day, that seems to be on the verge of evolving, as per Cortazar’s story “The Southern Thruway” (an inspiration for Godard’s Weekend), into some kind of makeshift settlement.
This has struck an enterprising verve in some locals, notes the BBC:
The drivers have complained that locals are over-charging them for food and drink while they are stuck.
Then again, what is the “market price” for selling food and drink to 100 km traffic jams?
Notes Witold Rybczynski, in an interesting slideshow of “ordinary places”:
Parking lots are also surprisingly civic. People politely observe rules of behavior for the sake of the common good, parking between the lines, staying out of the handicapped spaces, driving slowly. It is one place where cars and pedestrians happily coexist.
[Montgomery County] Employees calculated the numbers and were surprised by the frequency of parking lot accidents. Of the 1,496 pedestrians struck between January 2006 and June 2009, 324 had been hit in parking lots.
I have a short essay (accompanied by some excellent images) on the “traffic island” — that curious embankment of legally murky space carved from urban traffic channels, on which all manner of species dwell, from certain varieties of ants to political agitators, — in the current islands-themed issue of Cabinet. It’s not available online, but Cabinet is one of those journals you really want to hold in your hand, not your iPad.
“Where are we exactly — are we near the island?”
‘The “island” — is that what you call it?
“The traffic island. The patch of waste ground below the motorway. Are we near there?”
J.G. Ballard, Concrete Island
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.
Please send tips, news, research papers, links, photos (bad road signs, outrageous bumper stickers, spectacularly awful acts of driving or parking or anything traffic-related), or ideas for my Slate.com Transport column to me at: email@example.com.
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April 9, 2008.
California Office of Traffic Safety Summit
San Francisco, CA.
May 19, 2009
University of Minnesota Center for Transportation Studies
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)
Texas Department of Transportation “Save a Life Summit”
San Antonio, Texas
September 2, 2009
Governors Highway Safety Association Annual Meeting
September 11, 2009
Oregon Transportation Summit
Honda R&D Americas
San Diego, CA
October 21, 2009
California State University-San Bernardino, Leonard Transportation Center
San Bernardino, CA
Southern New England Planning Association Planning Conference
Texas Transportation Forum
(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
University of Utah
Salt Lake City
International Bridge, Tunnel and Turnpike Association (Organization Management Workshop)
Monday, April 26
Edmonton Traffic Safety Conference
Monday, June 7
Canadian Association of Road Safety Professionals
Niagara Falls, Ontario
Wednesday, July 6
Fondo de Prevención Vial
Tuesday, August 31
Royal Automobile Club
Wednesday, September 1
Australasian Road Safety Conference
Wednesday, September 22
Wisconsin Department of Transportation’s
Traffic Incident Management Enhancement Program
Wisconsin Dells, WI
Wednesday, October 20
Center for Advanced Infrastructure and Transportation
Tuesday, March 8, 2011
Ontario Injury Prevention Resource Centre
Injury Prevention Forum
Monday, May 2
Idaho Public Driver Education Conference
Tuesday, June 2, 2011
California Association of Cities
Costa Mesa, California
Sunday, August 21, 2011
American Association of Motor Vehicle Administrators
Wednesday, October 26, 2011
Attitudes: Iniciativa Social de Audi
April 16, 2012
Institute for Sensible Transport Seminar
Gardens Theatre, QUT
April 17, 2012
Institute for Sensible Transport Seminar
Centennial Plaza, Sydney
April 19, 2012
Institute for Sensible Transport Seminar
Melbourne Town Hall
January 30, 2013
University of Minnesota City Engineers Association Meeting
January 31, 2013
Metropolis and Mobile Life
School of Architecture, University of Toronto
February 22, 2013
March 1, 2013
Australian Road Summit
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