Archive for March, 2009

According to the Federal Highway Administration, Angelenos drive 23 miles per resident per day. This ranks the Los Angeles metro area 21st highest among the largest 37 cities. The champions (or losers) are probably Houston, followed by Jacksonville and Orlando, all of which are over 30 miles per day. New Yorkers drive the fewest miles (17 VMT per resident per day), thanks in large part to relatively high transit ridership and lots of walking trips.

This comes from Eric Morris’ final entry in his counterintuitive traffic quiz, dedicated to shattering all myths of Los Angeles mobility.

He goes on:

Despite our reputation, we Angelenos don’t exhibit any particularly great predilection for freeway travel either. Los Angeles ranks 14th out of the 37 largest metro areas in terms of highway miles driven per resident per day. To be sure, this is above the median, but it hardly points to the sort of unique freeway fetish Angelenos are accused of harboring.

But before you go toss that copy of L.A Story in the trash, on one important measure, L.A. is right where you’d expect, however: America’s worst congestion.

Jeff Mapes’ new book Pedaling Revolution is out, and he’ll be in New York on Friday for a Q&A/signing.

I provided this comment to the book’s publisher:

“Writing from Portland, the hub of the American cycling renaissance, Jeff Mapes, brimming with passion, humor and salutary insight, makes an admirably clear-headed, convincing and, ultimately, humane argument for making more room for the two-wheeler, in our lives and on our roads.”

We all intuitively know that a crash — or even a disabled vehicle or a piece of interesting debris on the roadside — can disrupt the flow of traffic. Cambridge Systematics has suggested that as much as 25% of congestion in the U.S. is due to “incidents.” Some of this due to physical loss of highway capacity (e.g., a blocked lane). But how much is actually due to drivers slowing down to rubberneck? (the dreaded “gaper’s block,” as they say in the Midwest)

Previous estimates have been based largely on models or “macroscopic” calculations. But an interesting bit of research — one version is here — by a Dutch team (Victor Knoop, Serge Hoogendoorn, and Henk J. van Zuylen, at the Delft University of Technology), to be published as part of this conference, has examined the “microscopic behavior” of drivers at crash sites, as well as quantified the actual loss in traffic capacity due to rubbernecking.

How did they do it? The authors write: “The observation team waited at the Traffic Management Center in the centre of the Netherlands until an accident had occurred somewhere nearby, after which it flew with the helicopter to the accident location. From the moment of arrival, traffic operations for both directions were recorded. From the other side of the road, the incident was visible but there was no physical obstruction.” They point out, by the way, that the helicopter was high enough to itself not be a cause of traffic disruption.

As pictured above, a light truck overturned near the city of Apeldoorn. One lane (in the ‘bottom section’ in the photo above) was closed for the sake of emergency response. Not surprisingly, given that a lane was missing, and two lanes had to merge, the researchers a large drop in “outflow capacity” in the section closest to the overturned van.

But what is striking is the airborne researchers observed a sizable effect — roughly a 50% capacity reduction — in the opposite bit of highway, in which no lanes were blocked. The video of this is rather amazing: At roughly the position that affords the best view of the crash, the traffic begins to bunch, as it does in stop-and-go congestion, even though the road ahead is otherwise clear. One vehicle, the “leader” is essentially slowing to look at the incident, creating in essence a backward “shock wave” that everyone else drives into. Once in the slowing wave, their curiosity is no doubt aroused and so they too continue to creep along for a look. At the exact point of the wreck, the traffic again begins to accelerate.

This raises the idea of the magical “first driver” in a traffic jam you may have wondered about as a child — the idea that there must be some driver at the head of even the longest traffic jam, and if only they would get going, or hadn’t slowed to begin with, things wouldn’t be so bad for us, etc. It also raises Thomas Schelling’s description of rubbernecking in the classic book Micromotives and Macrobehavior: Because they’ve already been made to wait because of everyone else’s look, each individual driver feels they too have the right to look themselves. Each person’s five seconds adds up to incremental delays (”it is a bad bargain,” he wrote). If everyone could only agree not to look, the congestion actually would not form.

There were a number of other interesting observations made. On the section of highway without any physical obstruction, the speed of vehicles in the left lane drops faster than those in the right (the authors speculate that left-lane cars are probably going faster to begin with; that they may be closer to the event and thus more distracted; and that there are more slower-moving trucks in the right lane).

Another curious phenomenon is that as the lead vehicle accelerates past the point of the crash, the time that the following driver begins to also accelerate varies more widely than under the “normal” conditions of heavy congestion. It is as if some drivers are simply more distracted by the sight of the crash, or perhaps some drivers instinctively behave with more caution in the immediate aftermath (the presence of emergency personnel may also affect driver behavior). All drivers react more slowly than in typical conditions, but some react much more slowly.

In any case, this is fascinating research that suggests the traffic impacts of rubbenecking are greater than those found in previous work.

Don’t know the whys or whos of this video (and has this driver been canned yet?) But it goes without saying that Romania is among the least safest places to drive in the European Union.

[UPDATE: See comments for further developments...]

From Australia. You know what they say, ‘big RPMs, …’

There are some striking passages in the new “Cycling in the Netherlands” report (via David Hembrow).

Wearing a bicycle helmet for daily trips is unusual in the Netherlands. Only competitive cyclists or mountain bikers tend to wear a helmet for their sport. Some parents give young children bicycle helmets. Usually the helmet is simply packed away for good before the offspring are 10 years old. There is certainly no support for mandatory helmeting. The fear exists that making it mandatory would cause a drop in bicycle use.

Sound dangerous? No, the reverse.

To talk about the relationship of bike helmets to safety is, it seems, to approach the situation in the wrong way. A useful analogy, I think, is to consider the presence or absence of certain species of birds in our environment. The near-disappearance of the peregrine falcon several decades ago was, it turned out, an indicator of the presence of toxic contaminants in our midst (it wasn’t just a bird problem, it was a human problem); we addressed the problem (somewhat), and the falcons returned. Conversely, the appearance of a flock of bike helmets could be read as a sign of safe and responsible individual behavior, or it could represent a species under attack in an unsustainable environment. To take another example, various species of woodpeckers have been on the decline, not just because of habitat loss, but because of the decline of natural processes, like fire, that give them the habitat they need. There too is a metaphor for cycling culture — without habitat, without the right habitat, a species won’t thrive. Given the Netherlands’ experience, helmets matter rather little — much more important are facilities, riders, enforcement, incentives, and the broader culture comprised of these things.

There’s all sorts of other interesting stuff in the report; e.g., this passage:

Most children are taught to ride a bicycle by their parents or a brother or sister at a very early age. This is less apparent amongst the growing of migrant population. Traditionally the bicycle is not part of Turkish or Moroccan culture. Often the parents cannot ride a bicycle, so no suitable bicycles are available in the household. In large cities with many migrants, extra attention is thus devoted to cycling skills in primary school. To ensure that all children gain cycling experience, the Amsterdam municipality makes bicycles available to schools, for instance. In a number of cities cycling courses for migrant women are also held. They can then master cycling in a protected environment. Many participants enjoy this as an opportunity to develop more skills.

The city giving bikes to schools — amazing! Here (in NYC) we read about community resistance to bike lanes so as not to interrupt the smooth vehicular conveyance of children to schools, typically in oversized vehicles that themselves are a threat to the urban environment.

Snark comes to the traffic safety world, via the Ad Council and The Daily Show’s Rob Riggle.

(Horn honk to Joseph Rose)

Via the St. Petersburg Times comes an interesting discussion of highway design featuring an old bugaboo, exiting on the left. In Traffic I spoke with some people at the FHWA who mentioned, essentially, that contemporary highway design tries to avoid exiting on the left, for a variety of reasons, including driver expectancy.

The piece brings up a number of issues. For one, it notes that three people have died on this section of highway, including one last week. No figures are given before that, though the facility opened in 1978. So whether this is an epidemic, or merely random, is hard to say; there may be a “regression to the mean” and we won’t see any further fatalities for the next ten years.

Second, and always lurking, is the issue of “driver behavior.” The most recent fatality, the article notes, was traveling 93 MPH. Is there a social responsibility for protecting someone behaving that negligently? If he had died by striking another vehicle, we wouldn’t be talking about bad design. Further, can good design save everybody (and what would the cost be)? I’d say we should be more worried, socially, about the harm that person may cause to others (and keeping those people off the road). The German autobahn was and is considered a design marvel; its smooth tarmac has also been home to many spectacular deaths.

The piece notes: “The left exit is counterintuitive, forcing drivers to slow down in the fast lane. The road’s elevation occludes a clear view of what lies around the corner. And the short, angled barrier walls do little to keep vehicles on the road, he said.”

Well, technically, people, there’s no such thing as a “fast lane.” There’s a passing lane. There’s also a speed limit. I also note a sign that clearly marks a reduction in speed on the ramp. And this isn’t really the sort of left-hand exit that people normally talk about giving drivers’ trouble — this is really the majority of the highway quite clearly swooping up and off to the left.

That said, the state engineers may be a bit too blithe in dismissing the risk. As a casual observer, I can imagine any number of small tweaks that could be done here relatively cheaply (cheaper than raising the height of the concrete walls). Rumble strips, flashing lights on the signs, etc. But I wouldn’t say this warrants some expensive overhaul — where’s the money coming from, anyway? — due to the actions of some severely negligent drivers.

(Horn honk to Shirl)

I’ve been attending an excellent (sold out) series at the New York Academy of Sciences called “The Science of the Senses.”

A recent night featured the amazing pickpocket/thief/magician/security consultant Apollo Robbins — featured in the above video — and the equally impressive cognitive scientist Christof Koch.

At one point, Koch was talking about the cognitive impairment of cell phones while doing something like driving. And then Robbins chimed in with another hazard I hadn’t previously considered. He noted — and this is a man who knows how to take things off of people — that a person walking along and talking on a cell phone is a red flag to a pickpocket. Why? Robbins’ work, while certainly involving some physical dexterity, is really about redirecting people’s attention. Not simply their eyes, but their entire focus of attention. A person talking on a cell phone has already allocated a good deal of attention to that conversation, is dedicating another good portion to walking down the street, and is thus less likely to notice someone like a pickpocket removing them of their valuables (everything but their cell phone, at least).

A new and occasional series of traffic facts that were novel to me.

I was in lovely Savannah, Georgia, yesterday at a AAA safety conference. I heard many interesting things (and managed to sneak out for some quick BBQ at Wall’s, a great place hidden in a house in an alley that I hadn’t been to in years and was worried may have closed in the intervening time).

One random fact I heard that was new to me was that Massachusetts has the lowest seat-belt wearing rate in the country. Somehow I had imagined some Western state (or maybe Alaska) would take top crown, not a relatively wealthy state with a concentration of high-tech and academia. Of course, the irony here is that Massachusetts, per mile, has the lowest fatality rate in the country — a fact that surely has to do with density (not so many chances to get in trouble, and lots of nearby trauma centers).

I’m not sure whether this is some expression of Emersonian self-reliance (neighboring New Hampshire is, of course, famously resistant to safety laws — “Live Free And/Or Die” is how someone put it). The reality, though, is that this non-seat-belt-wearing is actually not so self-reliant; this study shows the medical burden the state assumes in treating the unbelted occupants of cars in crashes. They also note, “Additionally, research has shown that the costs of unbelted injuries are 25% higher than belted injuries, and unbelted occupants are more likely to be Medicaid patients.”

An excellent BBC dispatch from Iraq notes the return of traffic police to the capital. I liked these lines, which describe the capital after the US-led invasion:

Traffic signals and direction signs became museum pieces, fragments of a dead language.

Baghdad has no parking restrictions. You could just pull up your car wherever you like. Something the car bombers used to good effect - you could drive right up to your target and no-one would stop you.

Photo by Tamika Moore

Speaking of traffic lights, apparently there’s a movement afoot to paint them black.

Reports The Birmingham News:

“Several states along the West Coast’s Sunbelt: California, Arizona and Nevada, use traffic signals encased in black housing to reduce glare, especially at sunrise or sunset. The black paint absorbs the sunlight instead of reflecting it back into the eyes of the driver.”

And a refreshingly frank assessment from the city’s engineer:

Birmingham Traffic Engineer Greg Dawkins said the black signal heads look better. “I found no compelling reason to keep the yellow, except that is the way it has always been done,” he said.

Reader Timothy writes in about the intersection of W. Broadway and Grand in Manhattan, “a notoriously noisy and difficult intersection.”

“This morning I watched for an hour while cars, trucks and pedestrians shared this space quietly…with civility!! little honking; no aggressive driving; no traffic cop.

Instead of a line of cars waiting for the light to change, alternate sides vying w/ each other for the few precious moments allowing them the right to pass thru….no one had to wait very long. And in fact the alternate sides traded back and forth, almost at a one-to-one ratio. No one had to wait, so no one got stuck in a line, so no one sped up, so no one honked, so there was no need for aggressive driving! even pedestrians got their due.

This is interesting (and hard to believe no one honked!), and I’ve heard things like before — newspaper accounts of how people felt, in blackouts and such, the traffic actually worked better. Or of how traffic police do a better job than lights (though the classic problem with police is coordinating intersections). Of course, it’s hard to really gauge things like flow from one’s own car, although sensing cooperative behavior is certainly possible. Whether it would last over a week or a month, instead of in a temporary situation, is another question. Still, one also hears, in those same blackouts, about the number of traffic accidents, and how they must be attributable to the blackout. Though this doesn’t explain the accidents on those days when the lights are functioning; but again, real data, as far as I can tell, is thin on the ground here.

Charles Komanoff (he of the Balanced Transportation Analyzer; Excel file here) runs the numbers on the Broadway pedestrianization project for John Tierney:

I figure that the proposal will slow motor vehicle traffic by an average of one-tenth of one percent (1 part per thousand), averaged throughout the Central Business District, i.e., a minuscule average impact. The current average speed of 10.350 miles per hour (on weekdays, averaged over 24 hours) will slow to 10.336 mph.

Pursuant to a few posts ago, that one-per-thousand decrease shouldn’t even warrant a loss in the Level of Service!

This post uses aerial imagery to graphically illustrate one man’s epic quest to find a parking spot in Toronto — stranded between overpriced off-street parking and underpriced on-street parking. A great way to illustrate the Schelling-esque example of how of how seemingly irrelevant individual actions can incrementally add up to negative collective outcomes. Shoupism in action!

(Horn honk to Reinventing Urban Transport)

Photo by Atwater Village Newbie/Flickr

“Level of Service” is a staple of traffic engineering. Its definition, according to the Highway Capacity Manual, is as such: “Level of service (LOS) is a quality measure describing operational conditions within a traffic stream, generally in terms of such service measures as speed and travel time, freedom to maneuver, traffic interruptions, and comfort and convenience.” It sounds clinical, inoffensive, and with its A through F letter grades, it fixes itself easily in the public mind. Says the parent: What, little Johnny’s getting an F? Well, we need to make improvements! Says the engineer: This facility has a Level of Service F. Well, we need to make improvements!

The “level of service” designation is a descendant of the strand of efficiency-minded engineering that came out of the Progressive age, a time which, as Peter Norton notes in his book Fighting Traffic: The Dawn of the Motor Age in the American City an important transformation took place: “Once a public space for mixed uses, and ruled by informal customs, the street was then becoming a motor thoroughfare for the nearly exclusive use of fast vehicles—especially automobiles.” Engineers went from counting people on streets to vehicles; and the key, seminal traffic engineer Miller McClintock went from arguing that “street capacity can be increased effectively by regulating traffic” to, once he had accepted funding from Studebaker, arguing for the “greater provision of street area [for automobiles].”

LOS is a classic case by which a bland bit of technical jargon conceals an entire ideology: Namely, that the purpose of a street is to move as many vehicles as possible, as quickly as possible. There are any number of problems that have been identified with that thinking. For one, how are we to judge the highway in the photo above? An economist might view it favorably as a piece of public infrastructure being used almost to its full capacity. But to a traffic engineer, that highway earns an “F”: “Operation with very high delays and congestion. Volumes vary widely depending on downstream queue conditions.” But another problem is that LOS designations are often issued during the peak morning and afternoon periods, meaning that a highway that looks like a failing “F” facility may be underutilized much of the rest of the day. Of course, this “building a church for Easter Sunday” is a staple of highway and parking demand modeling; we hear plenty about the economic losses due to congestion but never seem to hear about the economic losses of overbuilt, under-funded highways that are well under capacity most of the day. Another problem with LOS, particularly for urban environments, is that its view of the supposed “service” is entirely monocultural. The aforementioned “comfort and convenience” refers to drivers’ ability to whisk unimpeded from point A to point B, but says nothing about how pedestrians or cyclists or people living along that street may find it.

As an example, look at the photo below, which comes from an excellent paper by Ronald Milam, of Fehr & peers.

The existing intersection shown has a LOS of “E.” (even though, you’ll notice, it looks hardly filled here). The new sections being added represent “improvements” that will bring it up to Level E. But now imagine you’re a pedestrian. Suddenly the width of the intersection has doubled, and a more or less iron law of traffic engineering is that pedestrian safety declines as streets get wider. A study I cite in Traffic has also shown that adding lanes at an intersection is a process of diminishing returns, with increasingly less bang for one’s buck — but this too is something that gets swept under the rug in that unimpeachable move from “E” (bad) to “C” (good).

The LOS, with its seemingly quantifiable (if hollow) authority, washes over any other number of considerations. As Milam writes, “Widening a roadway to maintain ‘acceptable’ traffic flow may involve removing homes, trees, or open space in some cases; things on which a community may place a higher value than travel time. However, formal mechanisms don’t generally exist in local policies or procedures to weigh these factors against each other, so the LOS threshold usually takes precedence.”

What set me off on this LOS tangent was a post at Fehr and Peers’ blog about how the state of California is considering doing away with LOS. The Governor’s Office for Planning and Research, which is currently updating California’s Environmental Quality Act, has long relied on LOS to measure transportation impacts. But things could be changing, the post noted:

Which brings us to January 2009. OPR has released proposed changes to the CEQA checklist which eliminate the above language, replacing it with language relating to the number of automobile trips or vehicle miles traveled (VMT) a particular “project” would generate…

…This proposal comes on the heels of the City of San Francisco’s proposal in the Fall of 2008 to do just the same thing. It also follows an LOS Forum on this topic that was held at OPR in December. If adopted, it would mean that automobile LOS, which describes the level of congestion and delay on a road, would be abandoned in favor of impacts being based on the amount of automobile travel generated, irrespective of roadway capacity.

What do you think? Is LOS itself getting an “F”? Are other states moving to overhaul this obsolete tool?

As if drivers on cell-phones weren’t a big enough problem already, this one takes it to a new level. Via Jezebel:

Genine Compton of Dayton, Ohio, was pulled over on Thursday morning after police spotted her breastfeeding her baby (and talking on her cell phone!) while driving her other children to school. “If my child’s hungry, I’m going to feed it,” Compton, who is facing 180 days for child endangerment, says.

Jezebel notes: “Genine! If your baby needs to eat, that’s fine. But it’s probably best for both of you if you stop the car and get off the phone first, no?”

Yeah, and it’s, uh, also better for everyone else outside of her car.

Gary Richards solicits driving-on-cellphone horror stories.

The worst incident I came upon was about five years ago as a newspaper reporter in Anderson, when a young women was on a cell phone when she pulled out in front of a large truck. She was at a stop sign and stopped. But, for some unknown reason, she pulled out into the traffic, which was traveling around 55 mph. The truck had no time to stop and crashed into her. The girl died instantly. It was a very sad incident.

Newsweek surveys NYC’s new pilot project for Broadway (with a nice nod to Traffic).

When it comes to New York traffic, Broadway has long been identified as a key culprit. In 1811, urban planners laid out Manhattan’s grid of north-south avenues met by east-west streets, an efficient system of right angles. But those mapmakers left Broadway slicing diagonally through the city, and it’s caused havoc ever since. “Every time Broadway cuts through the grid, it delays traffic,” says Janette Sadik-Khan, New York’s transportation commissioner. It’s especially bad at Times Square, where drivers on Broadway and Seventh Avenue meet heavy crosstown traffic—along with 356,000 daily pedestrians.

Up in Boston, a different idea is being floated: Reopening Downtown Crossing to cars.

Indeed, Downtown Crossing remains one of the last vestiges of a largely discredited idea, the American pedestrian mall, which municipal planners once believed would help cities compete with proliferating suburban malls. In the 1970s, at least 220 cities closed downtown thoroughfares, paved them with bricks or cobbles and waited for them to take hold as urban destinations. Since then, all but about two dozen have reopened the malls to traffic, as planners, developers, and municipal officials came to believe that the lack of cars had an effect opposite of what they had intended, driving away shoppers, stifling businesses, and making streets at night seem barren and forlorn.