Archive for February, 2009

Readers have been asking for more motorcycle stuff, and watching this U.K. highways agency instructional video, particularly in the urban areas with everything going on, I couldn’t help but think back to the cellphone post: With all the stuff going on in this video, all the scanning and anticipation and hazard recognition, do we really want this guy on the mobile with his mate talking about yesterday’s Scunthorpe United result?

(Horn honk to DriveSmart BC)

Reading this item about violence on the increase as car repossessions rise sent me briefly into a 1980s nostalgic haze for the film Repo Man.

I always think of the last quote in that clip (“the more you drive the less intelligent you are”) after emerging from the car after a long drive.

I was bothered by this assertion in an editorial on cell-phones in cars:

Motorists who drive carelessly while on the phone — we’ve all seen them — are a hazard and should be penalized. The same is true for those who drive carelessly while operating their CD players, adjusting their GPS devices or fussing with their kids.

But a motorist driving attentively at a lawful speed on a safe, straight stretch of Interstate 5 should not be pulled over because of a telephone conversation.

Yes, obviously people driving recklessly, whether distracted or not, should be pulled over. But to assert that a motorist “driving attentively” on a “safe, straight stretch” of road while talking on a phone is beyond concern is a gross oversimplification of the emerging science.

It reminds me of a night, many years ago, when I was much younger and much more car-dependent (two conditions I do not long to return to), when I drove home in what can only be called a state of substantial intoxication — something I only became dimly aware of a number of minutes into the trip. Somewhat panicked, I rigorously drove the speed limit, and locked my attention on the road — “a safe, straight stretch” (I’ve said it before, “safe” is a relative term; the only objectively safe road is the one that’s never traveled).

In any case, by any external measure, I was just another law-abiding, prudent motorist. The fact was, however, that my physical impairments began with the first drink of the night and only got progressively worse, and that I very likely may have not been able to stop in the face of an unexpected “path intrusion,” or not seen a pedestrian in the crosswalk in time to react, etc. But I would not have been readily aware of the scale of this performance decrement, as all my attention was on keeping between the lanes and going the speed limit — which is not necessarily the same thing as safe, attentive driving. Of course, I may indeed have been drifting across lanes; but this feedback is not something always immediately apparent to drunk drivers.

This is the condition that cell-phone conversation presents. Even if there is not obvious “fiddling” with the phone (at least the person is aware of their distraction in that case) or drifting across lanes, there is still some portion of mental workload — higher than one would devote to a billboard, a passenger, or the radio — being dedicated to the task. The driver may still have enough left to operate the car in a seemingly effective manner, but it still leaves open the very good possibility that their performance would be impaired if something out of the ordinary were to happen. To our minds, we may be driving fine, by a certain measure, but just as we are fully unable to measure our own extent of distraction (often, one only realizes this afterward, as the miles traveled while talking have suddenly vanished from recollection, a sign of cognitive shedding), we also cannot predict how that distraction would leave us equipped to react to something unexpected. A car traveling the speed limit and staying within lanes is safe until the driver rear-ends someone who has unexpectedly come to a stop on the highway.

I am reminded of another good excerpt from a paper I referenced earlier this week, by Peter Hancock and colleagues, “On the philosophical foundations of driving distraction and the distracted driver,” in a recent book titled Driver Distraction: Theory, Effects, and Mitigation:

Driving, as we have seen, is a satisficing task. It is one in which all drivers frequently, and on certain occasions necessarily, fail to maintain their attention toward the “correct” source of attraction. Infrequently and unpredictably, these momentary failures encounter the precise environmental circumstances that induce collision. In Haddon’s terms, we “meet the tiger.” Society is content, in general, to chastise those unlucky drivers who find themselves involved in these rare collisions. This does not, of course, exempt those drivers who consciously make the decision to neglect to neglect their responsibilities. However, if collisions became more frequent by several orders of magnitude, society would not single out these ‘bad’ individuals but would seek to make corrections at a systemic level. However, we have been generally content to ratify our collective, institutional schizophrenia, which ‘blames’ the ‘bad’ drivers while encouraging the production of ever greater numbers of technologies that inevitably redirect drivers’ attention from the ever more satisficed task of vehicle control.

The editorial I referred to in the opening sentences wants to make this easy distinction between the “good” and “bad” driver. But it is not so clear; there are many “good” intoxicated drivers who become “bad” only when their blood is analyzed at a crash scene. There is also the problem of ethics: The individual driver may think talking on the phone is a good idea because they’ve done it “all the time” and they do it safely. But what is the moral consequence of participating in a behavior with known negative consequences for driving performance to other people? Already, just by getting behind the wheel, we are doing one of the few things in our life by which we easily have the capability to take someone’s life, accidentally or not; what is the ethical dimension to raising that likelihood, even marginally?

There is always the rejoinder, but why haven’t we seen a big increase in crashes and fatalities with phone use? The first point is there have been any number of fatalities already attributed to cell-phones; the second point is that most people do not talk most of the time, leaving more aware drivers to account for others’ mistakes — as a generation raised on Twitter hits the road it’s anyone’s guess. Another issue is that, perhaps through sheer luck, a majority of drunks make it home every night (should we thus do away with DUI?) And cars of course keep getting safer, which is no consolation to anyone outside the car, a condition common to most of us, even in America. In any case, this line of inquiry misstates the problem. The real question is not why there hasn’t been an increase but why we haven’t seen a great decline in this country (the recent small decline one was mostly due to economic factors) of traffic fatalities? Yes, driving per mile has become ever safer, but per-head of population the number killed is stubbornly similar to decades past. With each increase in car and road safety we seem to find new ways to make our own performance a touch more dangerous.

A sub-theme articulated in Traffic is the “slower is faster principle,” in which reductions in capacity or seeming performance can actually lead to no worse — and often better — outcomes vis a vis traffic flow.

I was thus intrigued to note, via the New York Times:

The city plans to close several blocks of Broadway to vehicle traffic through Times Square and Herald Square, an experiment that would turn swaths of the Great White Way into pedestrian malls and continue Mayor Michael R. Bloomberg’s effort to reduce traffic congestion in Midtown.

“The lower the volume is on Broadway — or if you eliminate it altogether — then traffic is going to move better,” Mr. Zupan said. “That’s one of the positive things that’s going to come out of this. The win-win is that the space that you’re freeing up will be used by pedestrians.”

What will be gained, depicted below via Streetsblog, is a rare pedestrian refuge (and a shorter, safer pedestrian crossing) in an unwelcoming area where foot-traffic seems to dwarf vehicular traffic. And while the results on traffic flow will certainly be worth following, that of course should not be the only consideration in judging the project’s success or failure. While not as radical perhaps as the early 1970s Madison Avenue pedestrianization, this one may have a better chance of succeeding.

I’m not sure if, lurking somewhere in NHTSA’s databases, there’s a category for “Car-House Crash” (no worries about coding for culpability there!), but, judging by the news reports I get, it happens more than you’d think.

It recently happened to a man in Toronto. Twice. Within three weeks. The article in the Toronto Star notes that residents and engineers think poor road design is to blame:

Johansen and other area residents blame the accidents on a reconfiguration of the Park Lawn-South Kingslea intersection a few years ago. The new intersection was moved a few metres west, and curves to the left just before the stop sign. But a laneway to the right, near the stop sign, can create an optical illusion that may fool some drivers into thinking it’s South Kingslea, and that the stop sign is in a traffic island in the middle of the intersection. As a result, they end up on the wrong side of the sign.

At least that’s the theory of Allan Smithies, who’s in charge of traffic planning in that area.

I haven’t been to the intersection in question, and it’s hard to draw inference from a photo, but as pictured above, I’m not quite sure what the source of confusion is. I see a Stop Sign, I quite plainly see a house. More importantly, I see other houses. It is a neighborhood. Neighborhoods are places where you don’t drive at speeds that would prevent you from not being able to crash into a house.

The local response was to place a set of “jersey barriers” in front of the house. The idea of living like the American embassy in Beruit didn’t please the homeowner.

But after assessing the path of the two vehicles that ended up in his house, Johansen said the barricade would be more likely to stop another vehicle if it was put up on the other side of South Kingslea, next to the stop sign and across the sidewalk on the east side of Park Lawn.

Rather than allow the barrier to be dropped in his yard, which he says would stigmatize his home as the target for airborne vehicles and not prevent further assaults, Johansen said he told city workers to stick it.

I can utterly side with the homeowner’s sentiment on this. Residential streets are not meant to be places for guard-rails, concrete barriers, and other aspects of the “forgiving road,” just as residents should not have to wear crash helmets when they go out for a walk. As I’ve argued here before, I’d rather see trees planted mid-block, every block, in the center of the block. Apart from that, there must be some better solution here than jersey barriers, any host of traffic calming treatments.

Of course, one doesn’t usually have to dig too deep in these stories to find the real source of the problem.

Around 1 a.m. yesterday, a car driven by a 25-year-old man hit a curb, flew through the master bedroom window of the house and landed on the residents’ bed. Police say alcohol was a factor in the crash and the driver has been charged with impaired driving.

This takes “breaking and entering” to a new level. But in any case, we see that it wasn’t necessarily some strange road illusion causing the problem, it was the fact that the driver was hammered. He was creating his own illusions.

What’s more, the article notes:

Neighbours in the area say many people don’t heed the nearby stop sign, which has been taken out a few times by previous collisions.

Now, I agree that good design of any sort should help users avoid unnecessary mistakes, or at least not make them more prone to make mistakes (TV remote-controls are notorious for this). But at what point do we say enough’s enough? As Hans Monderman has said, there are some drivers which no road can save. As, I’ve argued in Traffic, bringing the “foolproof” design of the forgiving road into places like neighborhoods not only cheapens the neighborhood, it increases the risk-taking behavior of drivers. I noticed that one poster referred to the fact that the “sightlines” were good; the problem with “sight distance” is that drivers simply consume the extra visibility with greater speed. It could even be that the stop sign itself is a problem — drivers are looking at that rather than scanning the actual terrain. Or maybe it’s just a Canadian snow and ice thing.

Now, I realize I’m sounding off here, and I recognize that traffic engineers, who must wrestle with the many-footed beast of human behavior, do not have an easy job by any means. If this finds its way to Mr. Smithies (or the homeowners) I’d be curious to hear more about the case.

(Horn honk to David)

Given that things like “same-store traffic” have been dropping, it’s no surprise that vehicular traffic has eased. Via the WSJ:

On average, Americans spent 13 fewer hours stuck in traffic in 2008 than in 2007, according to an annual road traffic report released Wednesday by Inrix. Inrix collects data on road congestion, in part, from a million vehicles equipped with GPS-enabled devices like cellphones and car navigation systems. Inrix cited volatile fuel prices as one reason for the decline in road travel, along with the economy. Some of the findings from the report:

– 99 out 100 most populous cities tracked by Inrix saw a decrease in traffic congestion last year from the previous year. The one city where traffic got worse last year: Baton Rouge, which saw a 6% increase in congestion from 2007.

Detroit is obvious, less sure about why Wednesday would see a particularly big drop.

“Let us consider for a moment you are driving down the road and approaching a signalized junction. The scene in front of you is a dynamic one and is constantly evolving. The light is at present green but of course this may change. The intersection is also currently clear, but of course this may also change. Now let us run the scenario forward. As you approach the actual crossing, the visual angle between the traffic light and the forward view across the junction begins to increase. There comes a point in time where one cannot see both together. This is not a divided attention issue or one or foveal versus peripheral field of view, it is a simple question of structural interference, the driver’s eye cannot see both at the same time. The design efforts of traffic engineers in terms of sight lines, seek to reduce any such occurrences of ambiguity, and on most occasions they are very successful. However, let us consider this example as one of inherent ambiguity. Where is the driver to look? If you look at the light to see a possible change, one cannot look at the intersection and vice versa. The pragmatist will say that by the time the light changes, the junction should be free. However, the simple fact is that driving presents many such ambiguous situations in which, whatever “correct” action one is actually accomplishing, there is another equally “correct” action that one must neglect. What of distraction in such circumstances? Can we say the driver involved in a collision in such circumstances is distracted and is not driving with due care and attention?”

That’s one of the many interesting bits of a paper by P.A. Hancock, M. Mouloua, & J.W. Senders, “On the philosophical foundations of driving distraction and the distracted driver,” in a recent book titled Driver Distraction: Theory, Effects, and Mitigation.

I enjoyed this chirpy, odd Finnish world (look at those narrow residential streets!) inhabited by crash test dummies.

The earlier posting on late merging reminds reader Joel of the issue of “lane splitting,” by which motorcyclists (and sometimes bicyclists) ride in the space between cars, ideally in heavy traffic. This is legal in California and other states, but, as he points out, it seems to raise drivers’ hackles (in places like Rome, of course, it’s an everyday fact of life, as scooters by the dozens “filter” between cars to settle near the front of stopped queues at traffic lights).

It’s an interesting, much-discussed issue (see here or here for example) because it raises so many of the issues that come up in traffic: Social justice (hey, why are they allowed to move when I’m stuck in traffic), different modes sharing the same road space, trading off risks, not to mention cognitive psychology.

Like so many things in traffic, it’s complex. In theory, I like the idea — why shouldn’t we use as much road space as possible? (the extra lane space put in for safety at high speeds is essentially wasted during congestion). A motorcycle between streams of cars shortens the length of the queue for cars, after all (and unlike HOV or hybrid lanes, doesn’t reduce existing highway space). On the other hand, there have been times when I’ve been absolutely startled by a motorcyclist unexpectedly passing me. This raises the question of the “attentional set”: If we don’t usually expect motorcycles to be there, will we not see them as we change lanes, or if we unintentionally “drift” a bit? (for the biker, the added problem is the people who don’t signal before changing).

And yet the smaller visual profile of motorcycles means we may not see them in front of us as easily as a car — not to mention the fact that the small fender-bender of stop-and-go traffic means more to a cyclist’s health than a car driver’s — and this brings up the point that has always been made vis a vis lane splitting: That being rear-ended by a car is a much greater hazard than riding between the lanes. The leading authority on this, and motorcycle safety in general, is Harry Hurt, author of the famous “Hurt Report” and now based here, who is quoted here as saying: “For a motorcyclist, that’s the safest place to be [between streams of traffic]… A lot of people think it’s a hazard, but the cold, hard facts are that it’s not.”

As far as I know, the “Hurt Report” has never been duplicated in size or scope, even as more motorcyclists have hit the road. The author himself seemed to think its 1970s-era findings, however, still hold valid.

As it happens, yesterday I was just reading a piece in Outside about the idea of bringing Asian-style “motorcycle taxis” to the U.S. The piece notes:

In the U.S., moto-taxis face two main obstacles. The first is insurance. When EagleRider, now the largest motorcycle-rental company, initially shopped for insurance, their rates were three times what they’re paying now. The second problem is a traffic law in 37 states that bans “splitting”—the practice of riding between lanes. Sounds unsafe, but even when allowed, it accounts for only 3 percent of motorcycle fatalities. When it’s outlawed, you’re stuck in crosstown traffic just like everyone else, only you’re breathing exhaust.

The 3% number is interesting; then again, if lane-splitting was only done when it is supposed to be, during slow or stopped heavy traffic, I wouldn’t expect large numbers of fatalities.

Any motorcyclists out there care to weigh in? Cyclists? Drivers? People selling things at traffic lights? (they too lane split)

And just to muddy the waters, speaking of social justice and road sharing, I’ve been annoyed lately to see motorized scooters chugging along in the bike lanes in Brooklyn and elsewhere. My knee-jerk reaction is ‘that’s not what their for” and ‘I don’t want your exhaust in my face’; but maybe I’m too harsh — perhaps if it’s otherwise unoccupied it’d be OK. But while it may make them feel safer, they may only be raising their exposure to “dooring” and other hazards.

Sometimes I weep for my country, I really do.

From the Shropshire Star:

A motorist caused traffic chaos at one of Telford Shopping Centre’s busiest car parks today when she launched a protest against paying – by blocking off the exits.

Drivers stuck in the jams caused by the woman’s protest said she seemed to be a tourist visiting from America and claimed they did not have parking charges in her country.

They also don’t drive on the left, let’s hope she didn’t try to protest that.

This post combines two of my recent obsessions — the atomic landscape and traffic (not to mention plugging my previous book), and the advertising image shown is typical of the times — playing on deep nuclear paranoia to help push a corporate agenda.

There’s an academic article, if not already done, to be written on the appearance of the mushroom cloud or other intimations of nuclear holocaust in 1950s advertising — I even have one in my collection for a paint company ‘now what should we paint the bedroom, honey? Nuclear winter?’ (no, it doesn’t really say that); in any case a mushroom cloud is no doubt more effective an image for road building than rote statistics about lost productivity.

In light of recent evacuation troubles (e.g., Katrina in New Orleans) with anticipated natural disasters, it’s hard to imagine that in a surprise strike on major population centers a nice new ribbon of asphalt would have really meant much to the average citizen.

Still, if you were going to hit the road, a “Survival Car” might have come in handy.

The Oregonian’s Joseph Rose is wished dead by an irate reader after discussing the potential benefits of “late merging.”

This made me all nostalgic as it was this kind of vitriol that launched me on the Traffic road: How could this simple activity stir such passion? While I am delighted to see the issue receiving further elaboration and exploration, I should only clarify here that I was not advocating a Universal Late Merge plan. There are circumstances where this behavior would actually make things worse. But the point was more that in certain scenarios, it would work better (better traffic flow, shorter queues, etc.), and that of course it would be better if drivers were instructed what to do — so as to not set off anger against the minority late merger position by early merge vigilantes — and then, having been instructed as how to properly merge, people then actually left these old prejudices behind (which trials have shown does not always happen).

But this is admittedly complex, for what makes late merging a better overall system for some highway segment may depend on a change to a certain level of congestion (in which case you’d need real-time ‘dynamic’ signage announcing the late merge), or it may depend on the number of lanes on the highway, or it may depend on the volume of trucks on a particular ‘facility.’ The correct cure depends on the set of symptoms.

Paul Collins, one of those writers whose name always arouses my interest in a table of contents, revisits the seminal days of car safety with an appreciation of Liberty Mutual and Cornell University’s open-source “Survival Car” in the latest New Scientist.

Edward Dye, director of Cornell’s crash injury project, noted that the design philosophy behind the car was the same as that for packaging any delicate object for shipping: “Use a strong packing case, fasten lid securely, pack tightly, and remove hard objects from the padding.” A conventional if sleek-looking saloon, the Survival Car sported a decidedly futuristic interior. Bucket “capsule seats” were firmly mounted to withstand a force of more than 2 tonnes, each featuring an integral head rest and roll bar and, of course, seat belts. The driver sat in the middle, with the passengers behind. Gone was the spear-like steering column and out went the lethal radio and heater knobs. In their place was an extraordinary hydraulic rudder control – a floor-mounted housing between the driver’s knees, with two stubby handles projecting out from the sides – and a padded dash with rounded and recessed knobs.

This proved a bit too radical — and expensive as it wasn’t a standard production car — so the team went back and overhauled a 1960 Chevrolet Bel-Air with inexpensive safety features.

American car firms were still not interested. A safe vehicle like the Survival Car was “completely unrealistic”, proclaimed John Gordon, president of General Motors. “This company is run by salesmen not engineers,” an engineer at Ford observed later. “The priority is styling, not safety.”

What happened next has become all too familiar. Spurning the opportunity presented to them, American car makers watched as others forged ahead. The first car on American roads to embody the Survival Car ideal was not from Detroit but from Solihull in the English midlands. It was the Rover P6 2000 of 1963, whose seat belts, thick padding, safer steering wheel and crumple zones moved consumer campaigner Ralph Nader to declare it “probably the safest car now available for general sale”.

Latest victim of the slumping economy, reports the Guardian: Sat-nav makers.

The NY Times reports that car sales in Japan have dropped by half since 1990:

“A survey last year by the business daily Nikkei found that only 25 percent of Japanese men in their 20s wanted a car, down from 48 percent in 2000, contributing to the slump in sales.”

James Dean’s eerily prophetic traffic safety PSA, filmed on the set of Giant. Some later work has tried to sort out why the crash happened (arguing for the inconspicuity of Dean’s car and perhaps a form of “inattentional blindness”).

An article in the Telegraph goes on to assert:

“Now, new evidence has emerged proving that not only was Dean driving safely, but at a much lower speed than was believed at the time.

A ground-breaking documentary by Channel 5, however, has unearthed evidence that Dean, contrary to what was said at the inquest into his death, was travelling at just over 70mph, up to 20mph slower than was claimed. It reveals that Dean braked hard, trying to avoid the car that cut across him, rather than using the throttle to accelerate around it, as was alleged at the time.”

Just over 70 mph on a state highway represents driving “safely”? (Dean had already received one speeding ticket before the crash; not to mention the crash protection of that era’s cars was minimal). This is not a scientific term. Would a 55 mph Dean have survived?

When I was at Google HQ this past summer I was struck by a few parking signs that said: “Expecting Mothers.” For some reason, I read it as for being for people who were waiting to pick up their mothers. Maybe it’s because we have nothing of this sort in NYC (at least that I’ve seen).

In any case, I was reminded of this by a recent dispatch from Kentucky:

Should pregnant women and new parents be afforded the same parking privileges as those with disabilities? It’s an issue that is stirring up controversy in the Commonwealth.

The Baker’s say they would be a little more open to the idea if more spots were created to accommodate new moms and moms-to-be. However, at this point, the bill does not include such a measure.

Is it me, or is this more than just a bit silly? Before you accuse me of insensitivity, my wife is well into her pregnancy and routinely walking fairly good distances around the city (longer than your average schlep in the Trader Joe’s parking lot). Most parking lots have too much capacity to begin with, and so adding extra spaces that will likely sit empty much of the time (except maybe at Pea in the Pod or some such) for a marginal social benefit seems highly inefficient.

Ray La Hood points to what is becoming, in light of the flagging and insufficient system of fuel taxes, an increasingly likely (and good) future scenario:  Rather than gas taxes, drivers will be charged for the miles they drive.

[Update: Political damage-control moves faster than mere bloggers:  Obama says no to VMT tax, via Ryan Avent]

Nothing brought the issue of older drivers into sharper focus than the 2003 crash at the Santa Monica Farmer’s Market, in which a 86-year-old man who had confused accelerator for brake killed nine people and injured scores more. As often happens in the media, something that had once basked outside of the light of attention suddenly became an “epidemic,” and untold numbers of stories warned us of the specter of the aging Baby Boom behind the wheel. This is, undoubtedly, a real issue, and the problems of the older driver do merit societal attention, but it is also likely that the circumstances of the Santa Monica event may have helped skew the actual risk posed: It was novel, it represented something out of our control, and, compared to most traffic fatalities at least, a large number of people were involved.

A new paper by Bryan Tefft, a researcher at the AAA Safety Foundation, published in the latest edition of the Journal for Safety Research, tries to put the older driver risk question into context, addressing some shortcomings of previous studies, most of which have not, as he notes, “analyzed responsibility for — as opposed to mere involvement in—crashes that kill other road users in relation to driver age, and none has done so while taking the amount of driving done by drivers of different ages into account.”

It is a truism of road safety research that a kind of u-shaped curve exists, in which the riskiest drivers are found at both ends of the age spectrum, as shown in the chart below, which comes from a Rand study (more on that later).

But this leaves out various, but important, parts of the risk equation, including: Which drivers (if any) bore a greater responsibility for the crash (an admittedly “noisy” bit of data), and the risk posed by certain classes of drivers to other drivers.

In any case, Tefft, using data from the FARS database, as well as “exposure” data from the National Household Travel Survey (and he notes using two different sources is a limitation of the work), comes to some interesting conclusions.

As other studies have found, he notes older drivers do have a greater risk of being involved in a fatal crash, but that this fatality risk is largely to themselves, as they are more likely, owing to increased “fragility,” to die in a crash than a younger driver. But as Tefft notes, “the degree to which older drivers’ risk to other road users is elevated depends strongly upon whether risk is measured on a per-driver, per trip, or per-mile basis.”

As an example, he writes, “if a randomly-selected driver in his or her thirties and a randomly selected driver aged 85 or older were to drive equal numbers of miles, the older driver would be over 1500% more likely than the younger driver to be responsible for and die as a result of a crash, and about 220% more likely than the younger driver to be responsible for a crash fatal to an occupant of another vehicle or a non-motorist.”

But, of course, most older drivers don’t drive as much as younger drivers, and they drive differently (i.e., they modulate risk based on their ability by choosing only certain roads, or certain times of day to drive, they may drive more slowly — insert Florida joke here — etc.). And so, while “a randomly-selected driver aged 85 or older is about 720% more likely than a randomly selected driver aged 30 to 39 to die in a crash, but only about 0.8% more likely to be responsible for a crash fatal to an occupant of another vehicle or a non-motorist, over the course of a year.” Per trip, the risk older drivers pose to others is “not statistically different” from drivers 30 to 39.

For the greatest source of risk from “without,” then, we need to look at the other end of the age spectrum. Tefft writes: “Drivers under age of 20 are responsible for more than twice as many deaths of occupants of other vehicles and non-motorists as are all drivers aged 70 and older.”

Tefft’s findings are supported by another paper — which uses another methodology (based on a technique created by Steven Levitt and J. Porter in this paper, which uses the drivers involved in fatal crashes as a surrogate for exposure) — namely, the Rand study mentioned above, “Regulating Older Drivers: Are New Policies Needed?,” by David S. Loughran, Seth A. Seabury, Laura Zakaras. They conclude: “In summary, we find that older drivers are only slightly likelier than other drivers to cause an accident but are considerably likelier to be killed in one. Younger drivers, on the other hand, are considerably likelier than other drivers to cause a crash, drive much more frequently than older drivers, and are less susceptible to fatal injuries than older drivers are.”

There are good reasons to be concerned about older drivers, but the news stories suggesting the greatest threat to our safety might come at the wrinkled hands of aging drivers seems somewhat misplaced. In strict terms of cost and benefit, it would seem wiser (assuming older drivers continue to do less driving than their younger peers), rather than rolling out new “mandatory retesting” programs in state DMVs (granted, one must leave open the possibilities these already existing programs have impacted the older driver crash rate), to ratchet up GDL programs at the other end — it really is shocking that driver’s licenses, in states like North Dakota, can still be had at age 14. Or simply cracking down on the most risky drivers, regardless of age, rather than blithely allowing people with clear patterns of dangerous driving to inhabit the roads (and, by the way, please don’t start on the sob story, ‘but it’s the U.S., you can’t function without a car…’). Demonizing older drivers may also subtly suggest to younger drivers, in their 30s say, that they have much less to worry about, when as Teftt’s per trip numbers indicate, may not be the case.

Via Streetsblog SF comes news of an innovative ‘pedestrian priority’ proposal for Jefferson Street at Fisherman’s Wharf.

Based on shared space or woonerfs, the plan calls for removing traditional traffic demarcations, such as the separation between streetbed and sidewalk, and slowing vehicle movement on the streets by making conditions less familiar for motorists. With 85,000 daily pedestrians and only 5,000 vehicles, 30 percent of which transportation consultants Nelson Nygaard estimated were cruising for parking or passing through, the proposal will use design elements to prioritize the street’s majority users. High visibility pavers will be used to demarcate pedestrian “safe” zones beyond existing sidewalks, and trees, benches, and street furniture will break up the street and create loose divisions meant to exclude vehicles while encouraging pedestrians to use the whole street for crossing, strolling, or standing…

Other treatments Planning hopes to implement are reduced speed limits of 5-10 mph, significantly lower than the minimum city speed limit of 25 mph, elimination of jaywalking regulations, and flexible traffic control devices like retractable bollards and gates.