Archive for the ‘Traffic Engineering’ Category

I just came across an article in the ITE Journal that speaks to some of the difficulties transportation engineers face in trying to manage and provide for varying modes of travel, particularly in environments where one mode dominates.

The article, “Trial Implementation of a Leading Pedestrian Interval: Lessons Learned,” by Sarah M.L. Hubbard, Darcy M. Bullock, and John H. Thai, describes the installation of an LPI (that’s where pedestrians get the “Walk Man” a bit before drivers get the green, so that “peds” can establish their presence in the crosswalk, and also be more visible) in Anaheim, California, near Disneyland.

While LPIs, at least in urban environments, have been found to be beneficial to pedestrians, at this location, the authors found, “the incidence of pedestrian compromise on the curb was found to be higher with the LPI signal timing than with concurrent signal timing for both low right-turn demand and high right-turn demand conditions.” In other words, things got worse for pedestrians with the LPI.

The culprit, they found, seemed to be the ability for drivers to make a right turn on red (yes, the only cultural advantage of California). “Drivers waiting to turn right at the red light are often watching for a gap in the oncoming traffic and may be unaware that the adjacent pedestrians have a WALK indication.” (One could get rid of the ROTR, of course, but that would, as the authors note, may cut right-turn capacity and could “actually reduce the service for pedestrians if drivers tend to accept smaller gaps between pedestrians and drive more aggressively as the v/c ratio for the right-turn movement increases” — in other words, the idiot factor may go up).

What goes unsaid here, but what I think is a more general underlying factor, is the sort of larger modal blindness that seems to occur in more suburbanized areas, like the one in which the trial was conducted. Judging by the photos in the article, the major flow street has at least four lanes in each direction, and presumably some rather high speeds. The overwhelming feel of such environments is that they are made for cars; and indeed are filled with cars, to the extent that drivers become rather programmed to looking out for the things that are important to them as drivers — lights, stripes, other cars. Pedestrians waiting to cross at a major intersections may be the victims of a kind of blindness by the drivers — either an actual kind of “attentional blindness” (they’re not looking for pedestrians so they don’t see pedestrians), or a kind of cultural blindness by which pedestrians are marginalized, and lose the rights that have been extended to them (though the number of “crosswalk” stings going across in urban areas across the U.S. should reveal this is by no means a suburban problem). I’ve noticed in Manhattan that some of the worst places to navigate on foot are near any of the bridge or tunnel entrances — either vehicles are still used to being in less pedestrian heavy environments, or their proximity to “escaping from New York” leads to a kind of animalistic imperative in which the only consideration becomes getting that many inches closer to the tunnel — woe to the person who has to cross on foot in one of these situations.

I’m not quite sure what that phrase means in this article, particularly if, as the article also states, people are doing 55 mph right through the heart of town (which would indicate plenty of road capacity), but is it me or does Lowell, Mass., based on this article, appear to be on the verge of getting things wrong in fixing their traffic problems?

Note this paragraph:

“For the next four years, MassHighway has slated $42 million in projects to improve Lowell intersections, including traffic signal improvements, bridge betterments and replacements, realigning the intersections, and the construction of a pedestrian bridge over the busy downtown thoroughfare, Thorndike Street .”

A pedestrian bridge? Why does this retrograde idea, imported from the anti-urban totalizing fantasies of modernist architects and itself a symbol of a decline of a place, still enchant traffic people? Well, actually it doesn’t much anymore, except in the developing world. How about a boulevard? A road diet? I dunno, a roundabout (if left turn crashes are as big as they say)? I don’t know Lowell or that street — anyone care to weigh in?

Photo by Tom Vanderbilt

A nifty little meditation on the visual language of the street, by Peter Campbell in the LRB (subscribers only; but you should really subscribe).

It begins: “Step into the street, look down, and it tells you what to do. Kerbs and gutters separate walkers from drivers. Painted words, lines and changes of material nudge you forward or make you pause. The street surface shows what is going on underground: scars left by repairs indicate new pipe work; trapdoors, lids, covers and grills point to drains, cables, coal holes and cellars. Signals of activity other than that created by people going from place to place proliferate. Responsibility for all this is diffuse.”

Photo: Eric Dumbaugh

As was recently reported in the Washington Post, Montgomery County, Md., is planning an overhaul of its “road code,” the sort of thing that seems like a bureaucratic footnote but then goes on to have major implications in the built environment.

Among the major issues, the newspaper reported:

The panel recommended that roads in urban areas be designed for speed limits of 30 to 40 mph, saying anything slower would be unrealistic and difficult for police to enforce. The panel also said trees should be planted farther from curbs on roads with 40 mph speed limits because of the danger they pose to motorists who hit them.

What strikes me in discussions like these is the weird disconnect between design and driver behavior. One of the reasons it can so often be difficult to enforce lower speed limits is that these limits are posted on roads that are intensely over-engineered. The supposed “fix,” as suggested above, is to assume that drivers are going to drive at a certain speed, and so to then rearrange the entire landscape — removing trees, etc. — to allow them to do so “safely.”

Of course, on the road “designed” for speed limits of 30 to 40 mph, they will inevitably drive faster. But then, of course, if someone crashes and kills a pedestrian or another driver, it’s an “accident,” it’s down to driver behavior; if they smash into a tree, it’s deemed poor traffic safety engineering. As the work of Eric Dumbaugh has found, looking at streets like the one above, at Stetson University in Florida, often the worst safety performance comes on the roads that are deemed “safe” by traffic engineers, while the best can come on tree-lined streets like the one above (which had no crashes and speeds below 30 mph during the five years he looked at it).

We consistently get urban speeds wrong in the U.S. In Germany, the land where speed is supposedly worshipped, the speed-limit free sections of the autobahn are contrasted by a mandatory, heavily enforced 30 KPH (that’s 18 mph, folks) limit in residential areas.

Another classic specter the article invokes is emergency response times. Any time a group seeks to lower speeds on a road, there are dark projections made of people being killed in fires because firefighters will be held up on traffic calmed streets. Well, for one, have you ever seen these vehicles on the way to an incident? They often don’t actually drive that much faster than anyone else — particularly since cars frequently don’t get out of the way in time — but I wonder if the lights and sirens and the panic they induce may make us overestimate their sense of urgency. In any case, studies have suggested that emergency-response teams are as likely to be help up by random traffic delays and the like as anything else.

But the larger issue is risk. As Reason magazine has pointed out, the risk of dying in a fire in the U.S. is roughly the same as drowning: In one year, 1 in 88,000, and, over a lifetime, 1 in 1100. The risk of dying in a car crash, according to the article, is 1 out of 6500 in a year. The risks of being killed while crossing the street. The risk of being killed while being a pedestrian? “A one-year risk of one in 48,500 and a lifetime risk of one in 625.”

Designing roads to meet some supposed emergency response criteria, for that dramatic last-second rescue, actually helps raise the risk of dying in a much more common way: In traffic.

Photo by Tom Vanderbilt

I was struck by these “arret” signs in Montreal, which have an additional sign informing the driver of which other roadways have a stop sign. In theory, I suppose, this is meant to be a good thing, giving the driver information as to who will be stopping, etc.

But there are a few problems. The first is that it took me a few weeks to even notice the supplementary information. The second is that often the sign is just providing redundant information (informing the driver, on say, a one-way street that the opposing street will not be stopping — but of course there will be no oncoming traffic as it’s one-way!). The third, as you can see in the photo, is that it just adds more information to an already complex and quite garish bouquet of warnings.

But the most objectionable thing about these signs is that they exist at all. These are scattered all over “Vieux Montreal,” which has a warren of narrow, pre-automobile streets, with an abundance of pedestrians and cyclists (and horse-drawn carriages). Drivers should be looking at the streets, looking around, not glancing up at a sign to discern who will be stopping and who won’t (that is, if they obey the sign in the first place).

I’m quoted a bit in this piece by David Filipov in the Boston Globe about the travails of merging in Massachusetts. One of the main issues seems to be a variety of design standards, each with its particular codes of behavior:

“State highway officials are aware of the yield problem. Neil Boudreau, State Traffic Engineer for MassHighway, experiences it every day on his commute to Boston on I-93. It’s more of an issue for the state’s older highways, he said. Although they have been upgraded to meet national standards for speed limits set out in a guideline Boudreau calls “The Bible,” many Massachusetts roads “were designed for a different era.”

But as a result, there can be different rules for different onramps, sometimes on successive exits. At Exit 7 of Route 3 in Plymouth, the connection with the new, high-speed section of Route 44 features the newfangled onramps, but Exits 6 and 8 on Route 3 are old-style, with shorter acceleration lanes and a yield sign.”

It’s actually a bit ironic that longer onramps need to be built today, as cars accelerate much faster now than they did in the days of those short ramps; the problem, I suppose, is that mainline flow is going much faster and there’s so many more merging interactions these days.

I’m intrigued by the technology described in this article to reduce so-called “dilemma zones” — i.e., the moment when a light is turning yellow and an approaching driver is caught in a dilemma: They’re going to fast to stop yet they may still catch some of the red.

The report notes: “Indecision within the dilemma zone contributes to crashes at high-speed intersections. If a car is traveling at a steady speed or accelerating in that zone, the sensor relays that information to the traffic light, which will give the car a longer green light and time to clear the intersection.

My only question here is the “human factor.” If drivers know they are to be rewarded by gunning it towards the intersection, may not that also pose all kinds of risks? If a steady stream of fast vehicles keeps getting picked up by the sensor, adding time to the signal, when does the signal ever decide to change?

The “induced travel” argument has a long history. This comes from Alvan Macauley, president of the Packard Motor Car Company, in a 1925 pamphlet titled City Planning and Automobile Traffic Problems:

“Since the advent of the automobile, however, the amount of traffic carried by a main thoroughfare seems to be dependent largely upon how many the thoroughfare can carry. Increasing the width of roadway and making possible an additional lane of travel each way will in many cases find the added capacity entirely taken up within a few months, either by diversion from other less favorable routes or by actual increase in the use of cars by those living in and passing through the city in question.

Just how this problem can be solved and what provision should be made for future increase in traffic it is difficult to state definitely, and to this extent a count of present traffic might seem to be void of direct results or even of value.“

When I came across this line on the website for Time, for a moment I assumed it must be another article talking about Shared Space, Hans Monderman, etc.:

“Since it scrapped its traffic light system four years ago, busy, industrial Bayonne, N.J. has had a substantial decrease in traffic mishaps.”

Then I looked at the date of the article: 1938.

I’m not sure what Bayonne replaced its lights with —anyone know? — perhaps early traffic circles.

In any case, the rest of the article has some enduring implications for contemporary traffic:

“No scientist has explained why. But last week, in the Journal of the American Medical Association, Cincinnati Physician Howard D. Fabing examined the behavior of the average motorist, found that traffic lights caused conditioned reflexes which made him as dithery as one of Russian Physiologist I.P. Pavlov’s famous third-degreed dogs.

One of Professor Pavlov’s dogs was taught that a circular light flashed on a screen meant food, that an elliptical light meant none. Then the ellipse was gradually rounded out until it was nearly circular, but no food. This psychological double-cross sent the dog into a nervous state called traumatic neurosis, from which he had to be rescued by rest and daily rectal instillations of bromides. An obedient motorist is conditioned to stop at a red light, to proceed at a green. But Dr. Fabing’s research marked the green as a treacherous come-on, since often just when a motorist steps on the accelerator the green light changes to red, so that his right foot must jump for the brake. Soon most motorists develop what Dr. Fabing calls an “anxiety neurosis in miniature,” mainly centred in an uncertain right foot, but with other noticeable effects. On himself, Dr. Fabing noted “a quickening of my pulse by 25 beats … a pilomotor [hair-on-end] response on my forearms, a dryness of the mouth, a sudden excessive sweating of the palms a feeling of epigastric distress.”

Not willing to suggest abolition of traffic lights, which most safety experts agree are necessary in heavy traffic, Dr. Fabing called attention to several patented, non-confusing systems. His recommendation: a clock-dial light with a rotating hand swinging from a green section at the top to a yellow caution light at the quarter-hour position, to a red section at the bottom, to another yellow caution light at the three-quarter-hour position— the hand always showing by its position how much green or red time remains.”

One of the themes in Traffic is the difficulty individual drivers can have in understanding how the system as a whole functions. Ramp meters are a perfect example: Many drivers, particularly at the moment they are asked to pause at the ramp-meter light before joining the freeway, are under the impression that they make congestion worse than if the highway were left to its “natural” state.

But a recent example from Atlanta provides yet another example of how ramp meters generally help, not hurt, traffic flow. Drivers may have to wait briefly on a ramp, but this typically means a faster trip on the “main line.” The concept is in some ways similar to way “congestion windows” are used to manage things like Internet traffic, holding up bits of incoming data if the network is already crowded.

Atlanta, by way of introduction, home of some of the U.S. worse congestion, has embarked on a ramp-meter spree, with 70 new signals coming online. In a recent paper presented at the Institute for Transportation Engineers conference (by Marion G. Waters III at Gresham, Smith and Partners), I came across this curious example of “before and after” (the after is in the photo above):

“A completely unexpected event occurred in March 2008 to validate the benefits of the existing ramp meters in use in Atlanta and to encourage their use in a system of traffic management.

A tornado hit downtown Atlanta for the first time (or at least in a very long time). It damaged one ramp meter and virtually destroyed another one. This was two of the four ramp meters being operated as a traffic-adjusted system on southbound I-75/85 in the downtown area.

The results were dramatic. Congestion on the main line of the freeway was noticeably worse, and the ramp congestion at the adjacent ramps became worse because the main line was completely full. Mainline operating speeds dropped (peak hour operating speeds) and were measured to be lower by as much as 16 mph in the most congested hour.

When these ramp meters were restored to full actuated operation, the conditions were reversed, demonstrating the effectiveness and value of the ramp meters working together in a system along a segment of freeway.”

The report goes on to note that since the meters were turned on in June, “the first indications are that free flow was extended an additional 10–20 minutes.”

An alert reader sends along some more coverage, this time by Isabelle de Pommereau in the Christian Science Monitor, of Bohmte, a German village that has become another waypoint in the evolving “Shared Space” movement (I was in the town a few years ago, for a Shared Space conference, but haven’t been back since things were changed). The town, like many, felt overwhelmed by the 13,000 vehicles per day coursing through its small center.

Readers of the book and blog by now may well know the drill:

“But this summer the town reworked its downtown thoroughfare, not only scrapping the traffic lights but also tearing down the curbs and erasing marked crosswalks. The busiest part of the main street turned into a “naked” square shared equally by bikes, pedestrians, cars, and trucks. Now, there is only one rule: Always give way to the person on the right.”

Bohmte is providing yet another surprising example of the types of environments in which this sort of thing can be done: “What’s revolutionary about Bohmte is that it took off its signs on a state highway with a lot of traffic,” says Heiner Monheim, a traffic management expert at the University of Trier, speaking at a recent European conference on sign-free towns convened here. Beyond that, Monheim says, the model’s real legacy is to have brought people closer to “rediscovering and appreciating cities not only as traffic places but also as human, social places.”

But I was also struck in particular by this passage:

“Two months into the experiment, ‘Instead of thinking, ‘It’s going to be red, I need to give gas, people have to slow down, to look to the right and the left, to be considerate,’ says Ms. Rubcic… The bonus? Town people recognize they have become a bit closer to one another. ‘The whole village has become more human. We look at each other, we greet each other,’ she says.”

One interesting, if unsettling, thing about traffic is that people often have a shaky grasp of the traffic code, or completely opposing views of what the “right” thing to do is. This piece from the Grand Rapids Press notes that when traffic lights malfunction, the average driver tends to treat the new condition as a four-way stop. But Michigan law, it seems, says that major roads and state highways have right-of-way preference. Some people want the law changed, others think it works fine.

But these differences of opinion can literally collide, as in the crash cited in the article. I was struck by the almost Beckett-like usage of the term “no-light,” hereby defined as: A state in which traffic lights are non-functioning.

“The westbound driver, James Boldi, 29, of Grand Rapids, was blamed, but, “I slowed down, stopped,” but the other driver didn’t. “The guy just drove through the no-light.”

I got a nice mention in a piece in this week’s Time on roundabouts:

“Carmel, Ind., is driving in circles. Since 2001, the Indianapolis suburb has built 50 roundabouts, those circular alternatives to street intersections that have become a transit fixture in much of the rest of the world. Because roundabouts force cars to travel through a crossroads in a slower but more free-flowing manner–unlike traffic circles, roundabouts have no stop signals–in seven years, Carmel has seen a 78% drop in accidents involving injuries, not to mention a savings of some 24,000 gal. of gas per year per roundabout because of less car idling. “As our population densities become more like Europe’s,” says Mayor Jim Brainard, who received a climate-protection award this year from the U.S. Conference of Mayors, “roundabouts will become more popular.”

About 1,000 roundabouts have been built in 25 states, and research bears out the benefits to states like Kansas, where the new design has produced a 65% average drop in vehicular delays, according to a recent Kansas State University study. Most roundabouts are also more aesthetically pleasing and cost much less to construct than stoplight intersections. The problem is teaching Americans how to navigate them. (Folks, cars entering a roundabout yield to those already in it.) But the heightened anxiety people feel in roundabouts makes them drive more carefully and remember that intersections are dangerous places. And as Tom Vanderbilt notes in this summer’s best seller Traffic, “The system that makes us more aware of this is actually the safer one.”

Ben Hamilton-Baillie, the Bristol-based “urban movement” specialist who, along with Hans Monderman, is a central figure in Chapter Five of the book, has a new paper out, “Shared Space: Reconciling People, Places and Traffic,” in the journal Built Environment (PDF available here, along with Ben’s other writings), that fully articulates the theory behind, and application of, “shared space,” a movement that is often reduced to quick soundbites along the lines of “let’s rip out all the traffic signs.”

Beginning with the simple example of a skating rink — a place where “informal social protocols serve to keep skaters moving in a roughly consistent direction” — Hamilton-Baillie moves through the historical evolution of segregated streams of movement in cities (grade-separated tunnels and bridges), before moving on to the first experiments, by Joost Vahl and others, towards the “deliberate integration of traffic into social space.”

One of Hamilton-Baillie’s favorite examples of this, in an ad hoc way, is the Seven Dials crossing, in London’s Covent Garden neighborhood (I now try to visit the Dials whenever I find myself in London — and that’s me sitting there above — as it’s a fascinating place to sit with a coffee and watch people go by). Some Londoners even think, mistakenly, that the Dials is a pedestrian-only space, when in reality, there is a quite steady stream of cars passing by, often within feet of people sitting on the central island. In the 16 years since its renovation, the Dials has seen no serious injuries.

Hamilton-Baillie goes on to show that he implicit lesson of Seven Dials — that people and cars can seemingly coexist in a largely unregulated system (as long as the cars are driven appropriately) — is now being tested in a number of other environments. This would include the famous roundabout in Drachten, but there a number of others as well, such as the Skvallertorget (Gossip Square) in the Swedish town of Norrkoping. There, all traditional traffic markings, and “suggestion of priorities or linear emphasis,” have been stripped from the plaza (which sees some 13,000 vehicles per day), and instead a “distinctive paving pattern reinforces the spatial qualities.” Now, most pedestrians seem to walk directly through the square, mingling with vehicles (whose speeds have reduced), without any accompanying increase in crashes or congestion.

In any case, the paper is an authoritative, fascinating look at what its author terms “a radically different vision for the streets of towns and cities for the future.”

In the ongoing series of local residents’ efforts to slow traffic in their neighborhoods, I bring you this fake speed camera, installed by a dentist in Hamburg.

Said the dentist: “This street leads to school and kindergarten. But it does not seem to interest the drivers. The limit is 60, but despite this they are always racing.”

The report notes the curious detail that because “Kaps’ fake speed radar does not emit a light which might endanger traffic, he has not broken the law.”

One of the oft-revisited themes in the book is that individual actors in traffic don’t often have an idea of what might be best for traffic as a whole. In a great piece in the New Scientist (sub required), “Why Complex Systems Do Better Without Us,” Mark Buchanan (whose book The Social Atom is high on my reading list), writing about the traffic physicist Dirk Helbing, makes the following point:

“Although the behaviour of individuals is often simple, the collective patterns to which it leads can be counter-intuitive, making common sense a faulty guide to what might happen. For example, it is generally true that traffic jams become more likely as traffic density increases. It’s not always the case, though, as Helbing’s group has shown.

Consider a two-lane road carrying both cars and trucks, where the cars are moving faster on average. At low traffic densities, the cars have plenty of space to overtake and can easily pass the trucks. As the traffic density increases, drivers find it more difficult to overtake because other vehicles are in the way. However, evidence from simulations and real traffic flows shows that at a critical density of traffic, the obstruction to lane-changing begins to have a beneficial effect. Because drivers tend to stay in one lane, they disturb the flow of traffic less, leading to a higher total throughput of vehicles.”

Another interesting strand in the piece is the notion that allowing traffic lights to control themselves would improve traffic flow. Instead of set timing patterns or even merely “synchronization,” the lights judge conditions for themselves and make constant adjustments (this is essentially the high-tech version of Hans Monderman’s “bottom-up” traffic scheme in the Netherlands). This is one of the next frontiers of traffic, and I’ve had described to me fascinating systems employing “genetic algorithms” for things ramp meter lights — the ramp meters would in essence keep learning over generations of traffic flow, evolving into smarter systems.

Of course, the new light schemes run the risk of not making sense to the individual driver, as Buchanan notes: “Nonetheless, the behaviour of the lights doesn’t generally fit with human notions of what ought to be efficient. “How long lights stay green is unpredictable,” says Lämmer. Yet the average journey times go down and become more predictable.”

The piece includes what may come to be a mantra: “Being in control, it seems, may increasingly demand being a little out of control.”

Rosalie Gascoigne, "Metropolis"

Just a quick alert that my Wilson Quarterly essay on Hans Monderman is now available online. I’ve also posted the text after the jump, but I always recommend checking out the WQ site in general.

(more…)

Hippie Gal/Flickr

In the New York Times Maura Casey writes about a tree in the middle of the road in her Connecticut town:

“Sometime, decades ago, town officials decided to pave around the tree instead of cutting it down for the convenience of cars despite the fact that it probably made more sense to remove it while widening the road. But it was a perfectly good tree, and someone argued, successfully, that it be left alone. In a world with little tolerance for eccentricity, it is hard to imagine that decision being made today.”

There’s absolutely no reason residential streets, like the one pictured above, shouldn’t have trees in the middle of the road. Apart from the aesthetic contribution, they’re great natural traffic calming devices. Yes, you have to slow down to navigate around them, yes they reduce the “sight distance” of whatever lays beyond (hence you have to slow down), and yes they are a crash “hazard” — if you act in a hazardous way.

Unfortunately, in too many places in America, someone would come along at a speed they shouldn’t be going — or maybe they’re otherwise “impaired” — and they smack into the tree, fatally or otherwise. The town, worried about safety and lawsuits, etc., calls for “improvements” to be made to the street — beginning with cutting down the offending tree as a “safety measure.” Of course, on the new widened, standardized road, speeds will thus increase, shifting the hazard from the drivers of cars to the residents of the neighborhood themselves. Idiot-proofed streets tend to breed idiotic behavior.

Those neighbors, grown tired of cars whizzing down their streets, may even turn to their own solution, as a group of residents in Seattle did (thanks to James Callan for the tip) when they bought speed bumps at Costco and installed them on their own streets in an effort to stop people from driving at speeds approaching 50 mph. This didn’t sit well with the Seattle DOT, who had the non-complying, offending devices removed. The kicker comes in the final line: “The city has already allocated $15,000 to the neighborhood, which can be used for traffic signs.”

Signs, as any number of studies have shown, are essentially useless at slowing drivers. That $15,000 would be better spent on a planting a tree or two — in the middle of the road.

One of the interesting things I gleaned from Jeffrey Kluger’s far-reaching book Simplexity is the observation, via NYC traffic guru Sam “Gridlock Sam” Schwartz, that during the worst of Manhattan’s traffic paralysis, the dreaded “gridlock,” some 60 percent of the city’s total road capacity would be available. “All of the action,” notes Kluger, “takes place in the intersections.”

One of the reasons, of course, is the dreaded condition of “blocking the box,” wherein drivers get caught out in the intersection on a red signal, thus obstructing the competing flow. This is fairly chronic behavior: One study found that at nine of Manhattan’s ten busiest intersections, some 3000 vehicles blocked the box over a nine hour period.

I kept experiencing this on a recent approach to the Holland Tunnel during the evening peak. As I stared at the large signs, warning of points off the license and fines, I found myself wondering if there were any more novel solutions beyond mere punishment (and there have been calls to increase ticketing of box-blockers). Was there a Nudge-style solution? I’m not sure the recent Nudge for speed reduction would work here, but maybe there’s something else?

While we’re on the subject of carrots rather than sticks, I was intrigued by this notice from the Times of India. On August 1st, in Hyderabad, drivers who obey the laws will be rewarded with a favorite Indian sweet: ” To get the lip-smacking dood peda, all you have to do is wear a helmet, carry original driving licence, RC, PUC certificate and insurance papers.” I dunno, maybe NYC traffic cops could give out Jolly Ranchers at intersections to drivers who don’t stray into the box?

Photo courtesy of CDOT

The recent discussion in the press of illusory speed bumps in Philadelphia reminded me of a conversation I had a while back with the Chicago Department of Transportation. For years, the curve at Oak Street on Lake Shore Drive has been something of a crash hot-spot. It’s within the typical engineering guidance for acceptable curves, but given that drivers on LSD tend to treat the Drive as an urban expressway rather than the boulevard it really should be, there’s been a consistent crash problem, particularly on rainy days and the like.

CDOT responded with a series of gradual alterations. They made the lane markings more distinct. They made the curve warning signs bigger. Then they added flashing lights. Drivers still weren’t getting the message. So CDOT got perceptual. (more…)