Why Women Cause More Congestion Than Men (and Other Secrets of Traffic) - Traffic: Why We Drive the Way We Do - Tom Vanderbilt

Traffic: Why We Drive the Way We Do (and What It Says About Us) - Tom Vanderbilt (2008)

Chapter 5. Why Women Cause More Congestion Than Men (and Other Secrets of Traffic)

Who Are All These People? The Psychology of Commuting

You’re not stuck in a traffic jam. You are the traffic jam.

—advertisement in Germany

One of the curious laws of traffic is that most people, the world over, spend roughly the same amount of time each day getting to where they need to go. Whether the setting is an African village or an American city, the daily round-trip commute clocks in at about 1.1 hours.

In the 1970s, Yacov Zahavi, an Israeli economist working for the World Bank, introduced a theory he called the “travel-time budget.” He suggested that people were willing to devote a certain part of each day to moving around. Interestingly, Zahavi found that this time was “practically the same” in all kinds of different locations. The small English city of Kingston-upon-Hull’s physical area was only 4.4 percent the size of London; nevertheless, Zahavi found, car drivers in both places averaged three-quarters of an hour each day. The only difference was that London drivers made fewer, longer trips, while Kingston-upon-Hull drivers made more frequent, shorter trips. In any case, the time spent driving was about the same.

The noted Italian physicist Cesare Marchetti has taken this idea one step further and pointed out that throughout history, well before the car, humans have sought to keep their commute at about one hour. This “cave instinct,” as he calls it, reflects a balance between our desires for mobility (the more territory, the more resources one can acquire, the more mates one can meet, etc.) and domesticity (we tend to feel safer and more comfortable at home than on the road). Even prisoners with life sentences, he notes, get an hour “out in the yard.” When walking was our only commuting option, an average walking speed of 5 kilometers per hour meant that the daily commute to and from the cave would allow one to cover an area of roughly 7 square miles (or 20 square kilometers). This, remarks Marchetti, is exactly the mean area of Greek villages to this day. Moreover, Marchetti notes, none of the ancient city walls, from Rome to Persepolis, encompassed a space wider than 5 kilometers in diameter—in other words, just the right size so that one could walk from the edge of town to the center and back in one hour. Today, the old core of a pedestrian city like Venice still has a diameter of 5 kilometers.

The growth of cities was marked, like tree rings, by advances in the ways we had to get from one place to another. The Berlin of 1800, Marchetti points out, was a walkable size. But as horse trams came along, then electric trams, then subways, and, finally, the car, the city kept growing, by roughly an amount proportional to the speed increase of the new commuting technology—but always such that the center of the city was, roughly, thirty minutes away for most people.

The “one-hour rule” found in ancient Rome still exists in modern America (and most other places), even if we have swapped sandals for cars or subways. “The thing to recognize is that half the U.S. population still gets to work in almost twenty minutes, or under twenty minutes,” says Alan Pisarski, the country’s leading authority in the field of “travel behavior.” For decades, Pisarski has been compiling numbers for the U.S. Census on how we get to work and how long that trip takes us. There seems to be some innate human limit for travel—which makes sense, after all, if one sleeps eight hours, works eight hours, spends a few hours eating (and not in the car), and crams in a hobby or a child’s tap-dance recital. Not much time is left. Studies have shown that satisfaction with one’s commute begins to drop off at around thirty minutes each way.

The enduring persistence of the one-hour rule was shown in a paper by urban planning researchers David Levinson and Ajay Kumar. Looking at the Washington, D.C., metropolitan area over a number of years from the 1950s to the 1980s, they found that average travel times—around thirty-two minutes each way—had hardly budged across the decades. What had changed were two other factors: distance and average travel speed. Both had gone up. They suggested that people were acting as “rational locators.” Because they did not want to spend too long commuting, they had moved to more distant suburbs. They had longer distances to drive, but they could now travel on faster suburban roads, rather than crowded city streets, to get to where their jobs were located. (Those in the center city, meanwhile, were probably walking to work or taking the Metro, meaning their times had hardly changed as well.)

“Wait,” I can hear you say, “I thought traffic was getting worse.” For many people, it undoubtedly is. The Texas Transportation Institute estimates that total traffic delay in the United States went from 0.7 billion hours in 1982 to 3.7 billion hours in 2003. In the twenty-six largest urban areas, the delay grew almost 655 percent in those same years. The U.S. Census noted that in most large cities, it took longer to get to work in 2000 than it did in 1990. The authors of the “rational locator” study took another look at the issue and decided that perhaps travel times were not stable after all. Perhaps, they suggested, it was a “statistical artifact.” Cities were growing larger every year, gobbling up new counties into their “metropolitan region,” so maybe more-distant drivers who were not tallied in previous surveys were now being captured, jacking up the numbers. Or maybe the suburbs that they had moved to previously to escape congestion were now themselves getting congested. Perhaps the total outcome of all that rational location had itself become irrational.

But why exactly is it getting worse? Or, to ask a question I sometimes do when I encounter unexpectedly heavy congestion in the middle of the day, “Who are all these people?” There are obvious answers, the ones you yourself suspect, like the fact that we add new drivers faster than we keep adding new blacktop. To take a quite typical American example: In suburban Montgomery County, Maryland, just outside Washington, D.C., the population grew by some 7 percent between 1976 and 1985. The number of jobs grew too, by 20 percent. But vehicle registrations nearly doubled. The county, which hardly built any new roads at all during that period, was suddenly awash in cars. Studies show that when a household has more vehicles, it not only drives more as a total household, as one would expect, but each person puts on more miles, almost as if the presence of those extra vehicles prompts more driving.

Affluence breeds traffic. Or, as Alan Pisarski describes it, congestion is “people with the economic means to act on their social and economic interests getting in the way of other people with the means to act on theirs.” The more money people have, the more cars they own, the more they drive (with the exception of a few Manhattan millionaires). The better the economy, the more miles traveled, the worse the traffic congestion. This is the interesting thing about studying traffic 'margin-bottom:0cm;margin-bottom:.0001pt;text-align: justify;text-indent:12.0pt;line-height:normal'>One striking thing the numbers seem to reveal is that women now make the largest contribution to congestion. (Another way to look at this is that they also suffer from it the most.) This seems like a controversial statement, and indeed one like it got a highway official booed at a conference. The statistic doesn’t assign fault or suggest that women working is a bad thing; it does provide a fascinating example of how traffic patterns are not just anonymous flows in the models of engineers, but moving, breathing time lines of social change.

Many of us can remember or envision a time when the typical commute involved Dad driving to the office while Mom took care of the kids and ran errands around town. Or, because many American families had only one car, Dad was driven to the morning train and picked up again just in time for cocktail hour and Cronkite. This is a blinkered view, argues Sandra Rosenbloom, an urban planning professor at Arizona State University whose specialty is women’s travel behavior. “That was just a middle-class model,” she says. “Lower-class women always worked. Either alongside husbands in stores, or at home doing piecework. Women always worked.”

Still, the Leave It to Beaver commute was not a total fiction, given that in 1950 women made up 28 percent of the workforce. Today, that figure is 48 percent. How could the roads not have gotten more crowded? “The rise in the number of cars, driver’s licenses, miles traveled—it totally tracks women going into the labor force,” says Rosenbloom. “It’s not that men wouldn’t have driven more, but you wouldn’t see these astonishing increases in traffic congestion in all indices of travel if women weren’t in the labor force, driving.”

The rise in working women is only part of the story. After all, they still represent a minority of the workforce, and studies show that men still rack up more miles when they drive to work. But work is an increasingly small part of the picture. In the 1950s, studies revealed that about 40 percent of daily trips per capita were “work trips.” Now the nationwide figure is roughly 16 percent. It’s not that people are making fewer trips to work but that they’re making so many other kinds of trips. What kinds of trips? Taking the kids to school or day care or soccer practice, eating out, picking up dry cleaning. In 1960, the average American drove 20.64 miles a day. By 2001, that figure was over 32 miles.

Who’s making these trips? Mostly women. This is the kind of social reality that traffic patterns lay on the table: Even though women make up nearly half the workforce, and their commutes are growing increasingly close in time and distance to men’s, they’re still doing a larger share of the household activities that, back in the Leave It to Beaver days, they may have had the whole day to complete (and, as Rosenbloom points out, 85 percent of single parents are women). “If you look at trip rates by male versus female, and look at that by size of family,” Pisarski says, “the women’s trip rates vary tremendously by size of family. Men’s trip rates look as if they didn’t even know they had a family. The men’s trip rates are almost independent of family size. What it obviously says is that the mother’s the one doing all the hauling.”

In fact, women make roughly double the number of what are called “serve-passenger” trips—that is, they’re taking someone somewhere that they themselves do not need to be. All these trips are squeezed together to and from work in a process called “trip chaining.” And because women, as a whole, leave later for work than men, they tend to travel right smack-dab in the peak hours of congestion (and even more so in the afternoon peak hours, which is partially why those tend to be worse). What’s more, these kinds of trips are made on the kinds of local streets, with lots of signals and required turning movements, that are least equipped to handle heavy traffic flows.

Another way trip chaining has helped increase traffic congestion is that it has made carpooling virtually impossible. Who wants to share a ride with someone who is going to day care, picking up laundry, dropping by Blockbuster, stopping at Aunt Clarice’s (“but just for a second”)? Carpooling keeps dropping in the United States (save among some immigrant groups), but “fam-pools,” car pools made up of family members (and almost 100 percent of fam-pools are only family members), keep rising. An estimated 83 percent of car pools are now fam-pools.

This raises the question of whether car-pool lanes are a good idea that has gone bad. If most people “carpooling” are simply toting their families around, taking no additional cars off the road and statistically driving more miles (thus creating more traffic), why should they get a break on the highway? Is a policy meant to reduce the number of drivers just acting as a “mommy lane,” enabling drivers with children to do their trip chaining more quickly and thus encouraging more of it? (Some pregnant women have taken this to extremes, arguing that their unborn children are precocious car poolers).

That women suffer more from congestion, even if at the hands of other women, is demonstrated in the high-occupancy toll lanes (HOT lanes, a.k.a. Lexus lanes) in cities like Denver, where drivers pay more to travel on less congested roads. Rosenbloom notes that studies show that women pay to use the lanes more often than men do—despite making less money on average. “And they are not just high-income women,” she says. “Even if you don’t make very much money, you’ve got to get your kids from day care. Every minute they stay over, they penalize you. Or these women have second jobs they have to get to on time.”

Women are not to be blamed for congestion, Rosenbloom argues. “The fault is the way families live today. The car is the way the two-worker families balance all the things they have to do.” Where children might once have been cared for at home, they are now shuttled to day care. Where it was once the overwhelming norm for children to walk to school, today only about 15 percent do. Parents on the “school run” are thought to boost traffic on the roads by some 30 percent.

Parents’ chauffeuring duties hardly end there, however, as the increasingly hyperscheduled “free time” of children, with its scores of games, lessons, and playdates, requires route planning and logistics that would turn a La Guardia air-traffic controller’s hair gray. It’s estimated that from 1981 to 1997, the amount of time children spent in organized sports in America doubled. All those games and all those practices, in increasingly far-flung suburbs, required rides. A new demographic entity, the so-called soccer mom, started hitting the roads big-time. “In the entire time I played baseball, my parents didn’t watch me play ball once,” recalls Pisarski, who is in his sixties. “I didn’t feel slighted, because no other kid’s parents were there either. Today you go to a game, and there’s a hundred and fifty people and everybody gets a trophy.”

Traffic, Pisarski emphasizes, is the expression of human purpose. Another huge way in which those purposes have changed is due to rising affluence. It’s not just that American households have more cars, it is that they are finding new places to take them. And once you have shelled out for a car, the comparatively marginal cost of another trip is barely noticeable—in other words, there is little incentive not to drive.

Given that Americans increasingly spend much of what they make, it should come as little surprise that much of our increase in driving seems to stem from trips to the mall. From 1983 to 2001, the number of annual shopping trips per household almost doubled—and those trips are getting longer. Each year, the amount of driving we do for shopping would take us across the country once and almost all the way back again. Statistics now show that more people travel on Saturday at one p.m. than during the typical rush hours. The more money one has, the more choices one has, and so it’s not surprising that nearly half of trips families make to supermarkets are not to those closest to their home. Pisarski notes that he, like many Americans, does not suffer for choice when it comes to food shopping, and his driving reflects this. “I go to Trader Joe’s because I like their string beans. I go to Harris Teeter because their seafood is better than Giant. In effect, we are just more selective.” Studies confirm that people shop at more grocery stores than they did a few decades ago.

You might think that the rise of larger, consolidated stores like Costco or Wal-Mart Supercenters, which offer one-stop shopping, might have actually helped cut down on the amount of shopping trips. But larger stores need to serve more people, which means, in effect, that they’re farther away from more people. (A similar trend has also occurred with schools, which explains some of the decline in children’s walking.) A study of Seattle grocery stores found that in 1940, the average store was .46 miles from a person’s house, while in 1990, it was .79 miles. That small change in distance was basically the death knell for any thought of not driving to the store, for a half mile is as long as planners believe the average person is willing to walk. Even if the stores are bigger, moreover, we are going to them more frequently—the number of grocery trips per week almost doubled from the 1970s to the 1990s.

The reason we see so many people on the roads, getting in our way, is that so many of them are doing things that used to be done at home. This, too, is a function of affluence, but it’s a complicated relationship. Do we drive to a restaurant for take-out food because we can afford it or because we are so busy trying to make money we have little choice? Either way, these sorts of social changes have their effects on traffic—often so fast that engineers can’t keep up. When Starbucks began serving customers at drive-throughs a few years ago, the people who study traffic flows were caught flat-footed. Their models for what is called “trip generation”—basically, the additional traffic flow a new business will create—included numbers for “Fast Food Restaurants with Drive-Through Window,” as well as for “Coffee/Bread/Sandwich Shop,” but “Coffee Place with Drive-Through Window” was completely alien. For Starbucks, which will go so far as to put stores on opposing corners to capture different traffic flows and spare drivers the agony of having to make a left turn during rush hour, the drive-through represented a natural progression in its slow evolutionary insertion into the daily commute.

“Can you imagine, thirty years ago, saying nobody will make coffee at home?” Nancy McGuckin, a travel researcher in Washington, D.C., asked me on a break during an annual traffic conference. In her research, McGuckin (whom one colleague called “the queen of trip chaining”) fingered coffee as a prime culprit in a dramatic new shift in traffic patterns. Men, it seemed, were suddenly doing more trip chaining. Sure, some were dropping off kids, but more were making a latte stop. She calls this the “Starbucks effect.” The prime demographic, she says, is middle-aged men. “Who knew they needed ‘me time’?” she asks. “We’re used to women saying this: ‘We’re so busy, we need “me time.”’ But it was middle-aged men who were making that stop at Starbucks in the morning. I had some of them saying they were leaving their homes before it becomes chaotic with the backpacks and the school. [He wants] to get up and leave the house and go to Starbucks, where, by golly, there’s somebody there who greets him by name, knows what his favorite drink is. It’s like his time to prepare for the office environment. I don’t think the psychology of that has been explored very well.”

The same might be said for the psychology of commuting itself. It does not seem unreasonable to wonder why, if traffic is so bad, more people keep choosing to drive more miles. This question puzzles all kinds of people, from economists to psychologists to traffic engineers.

One important thing to consider, of course, is that for many Americans it is not so bad. They still get to work and back in that same roughly one-hour time frame. In relative terms, American commute times, Pisarski argues, should be “the envy of most places in the world.” In cities like São Paulo, where the congestion is so bad “motorcycle medics” are needed to ferry patients between stalled queues of cars to the hospital, average daily travel times clock in at upward of two hours. The average car journey takes up to one-third longer in Europe than it does in the United States (which is perhaps why Europeans make fewer car trips). Driving to work alone, which is what nearly nine out of ten Americans do, is still, on average, about one and a half minutes faster than the average time for all other travel methods. One study that looked at the working poor found that those with a car were able to get around three times more quickly than those without one. Even people who do not own a car are more likely to commute via car than public transit.

Trying to crack the commuter psyche is rather bewildering work. On the one hand, people seem to hate commuting. When Princeton University psychology professor Daniel Kahneman and some colleagues surveyed a group of women about their experiences in a typical day and how they felt about them, commuting came in at the bottom. (“Intimate relations” and “relaxing with friends” were near the top.) On the other hand, Patricia Mokhtarian, a professor of civil engineering at the University of California, Davis, has found that when people were asked to name an “ideal” commute time, their mean response was not, as you might expect given its popularity in the aforementioned survey, “no commute” but sixteen minutes.

In another study, Mokhtarian and two colleagues located what they described as “an apparent paradox.” When people were asked if they drive more than they would like to, the response was a unanimous yes. When those same people were asked if they drive more than they need to, the response was a nearly unanimous yes. Why were people seemingly acting against their own interests? Why were they doing more of what they wanted to do less of? The researchers surmised that the driving people didn’t want to do was, in fact, the driving they needed to do. Maybe it was the reasons they were driving that they wanted to eliminate, rather than the driving itself. Or maybe driving just seemed easier than figuring out alternatives.

A pair of Swiss economists have identified another kind of commuting paradox. They begin with the assumption that commuting, with its toll of time, stress, spilled coffee, and crash risk, is a “cost” that people rationally figure into their decisions about where to live in relation to where they work. If you have a long commute, that should be reflected in either a high-paying job or a nice house. The benefits that those things bring should offset the longer commute; in other words, a longer commute should not make you more unhappy. But that’s precisely what the economists found in a study of German commuters; the researchers concluded that people making just the average twenty-three-minute commute would need a 19 percent salary raise to make the commute “worth it” from a rational perspective.

Commuters may, of course, have little choice. Housing might simply be too expensive close to where people work, so they’re forced to live farther away from their jobs than they would like, out past the billboards that chide, “If You Lived Here, You’d Be Home by Now.” The economist Robert H. Frank, comparing U.S. Census data between 1990 and 2000, found that commuting grew the most in counties in which income inequality had grown the most. He calls this the “Aspen effect,” after the affluent Colorado city, which keeps expanding because the middle-class people who work in the town keep having to move farther away to find affordable housing. But there is a paradox here as well: Statistics show that commuting miles rise, not fall, with income. In other words, the people with the money to live close to the action seem to be doing more of the driving. Maybe those people are moving farther out in Aspen because they have more money, and they’re choosing to buy bigger homes despite the commute.

This, however, is where things start to go wrong, according to many psychologists. A commuter who lives in the older suburb of Eagle Glen decides he wants to move to a new, bigger house in Fledgling Ridge. Getting the bigger house requires adding twenty minutes to his commute. This seems worth it because the bigger house provides such a boost to his quality of life. But gradually, that rosy glow fades. He quickly undergoes what psychologists call “hedonic adaptation.” Suddenly, the newer, bigger house just seems normal. Everyone else has the same newer, bigger house. Meanwhile, the commuter has lost time (more of which cannot be made, unlike money). This means less time to do the things that are shown to actually bring happiness. He’s locked into a longer commute, and studies show that the longer a commute is, the more prone it is to variability—to be longer or shorter than you expect. And some studies show that we are bothered more by changes to our commute time than by the actual time itself. As Harvard University psychologist Daniel Gilbert argues, “You can’t adapt to commuting, because it’s entirely unpredictable. Driving in traffic is a different kind of hell every day.”

For a portrait of a driver in purgatory, consider urban bus drivers. Few drivers face as much traffic or are as affected by changes in their commuting schedule. The hassles they endure are legion, from the simpleton car drivers who accuse them—irony of ironies—of “causing” congestion to passengers yelling at them for being late. Despite the size of the buses they drive, they are struck by other vehicles at a higher rate than are passenger cars. And what happens to them? Studies of drivers in various countries have shown they have more stress-related hormones in their system than other people—including themselves before they started driving for a living. The worse the traffic, the higher the hormones. Medical ailments send more than half of them into early retirement. No wonder Ralph Kramden of The Honeymooners was always so grouchy!

The problem with the models used in the Swiss researchers’ commuting paradox is that they rely, essentially, on asking people to turn their feelings into numbers. This is slippery stuff, prone to all kinds of biases. Psychologists have found, for example, that when college students were asked two questions, one concerning the number of dates they had in the previous month and the other concerning their general sense of life satisfaction, the results varied with the order in which the questions were asked. Ask about life satisfaction first, and this does not change the way they answer the dating question. Ask about dating first, and suddenly the students’ idea of how happy they are seems to vary with how much they’re dating. This has been called the “focusing illusion.” Things become more important when we think about them. Ask a person how long their commute is, and then how happy they are, and they might give an answer that is different than if you had not first asked them about commuting. Maybe this betrays how unhappy their commute is really making them. Or maybe commuting is just not that important to their overall lives—until a researcher’s question makes them think it is.

This is the murky, human side of traffic. Engineers can look at a section of highway and measure its capacity, or model how many cars will pass in an hour. That traffic flow, while it may mathematically seem like a discrete entity, is made up of people who all have their own reasons for going where they are going, for enduring that traffic. Some may have no choice; some may choose.

Moreover, Brian Taylor, a professor of urban planning at UCLA, observes that when we travel to work by car, there may be any number of parts to that journey. We may walk to our car, drive down our residential block, briefly cruise a larger arterial, then pop onto the highway for a spell before exiting onto another arterial, continue on to a smaller street, then drive up a parking-garage ramp, walk to the elevator, and finally walk to our desk. In the course of Taylor’s hypothetical commute, the highway portion could be over half the distance traveled but less than half the time (and we perceive a minute of driving on a highway as shorter than a minute of walking to our car). Taylor notes that even if the speed on the congested highway were doubled, the total time saved would be less than 15 percent. For all these reasons, we cannot look at a jammed section of urban highway moving at fifteen miles an hour and assume that everyone is suffering, or suffering in the same way.

The Parking Problem: Why We Are Inefficient Parkers and How This Causes Congestion

Everyone in New York City knows there’s gotta be way more cars than parking spaces. You see cars driving in New York all hours of the night. It’s like Musical Chairs except everybody sat down around 1964.

—Jerry Seinfeld

The next time you find yourself at a shopping mall or a store with a large parking lot where the store entrance more or less divides the lot in half by width, take a moment to observe how the cars are arrayed. Unless the lot is completely filled, you may be able to observe a common pattern. Chances are, the row that is dead opposite the store entrance will be the most filled, with cars stretching far out along the row. In each adjacent row, there are likely to be slightly fewer cars. This pattern will continue sequentially in each row so that if one were able to gaze down at the lot from above (as anyone can with Google Earth), the cluster of cars might look, depending on the lot’s occupancy, like a giant Christmas tree or, perhaps, like a bell.

If you were to further study this bell-curve arrangement, you might conclude that the cars parked in the row closest to the store entrance but farthest out along the row are actually farther from the store entrance than many of the open spaces in the rows off to the side. Why is this so? Why don’t parkers gravitate first toward the closer spaces? Perhaps parkers are not good geometricians. People may park in the row opposite the entrance, no matter how far away, because it will be easier to locate their car later. Parkers may find the center aisle, with its line of sight to the entrance, safer—even in open-air lots during the day. Or it may be that parkers optimistically sail to the closest row and, once having entered it, simply grab the first piece of what seems to be an increasingly scarce resource.

Whatever the case, something curious happens in parking lots. It seems that the people who actively look for the “best” parking place inevitably spend more total time getting to the store than those people who simply grab the first spot they see. This was the conclusion that Andrew Velkey, a psychology professor at Virginia’s Christopher Newport University, came to after he studied the behavior of parkers at a Wal-Mart in Mississippi. Incoming cars were tracked; once they had acquired a parking spot, Velkey and his team measured the distance of the car to the entrance, as well as the time it took the driver to walk into the store. They observed two distinct strategies: “cycling” and “pick a row, closest space.” They compared the results. “What was interesting,” Velkey told me, “was although the individuals cycling were spending more time driving looking for a parking space, on average they were no closer to the door, time-wise or distance-wise, than people using ‘pick a row, closest space.’” This is precisely what the pattern mentioned above had suggested: The best parking spaces, by distance or time, were not necessarily being chosen.

Were people just being lazy, or were they succumbing to cognitive biases? Bring a stopwatch on your next trip to the mall and see for yourself. Research has shown that people tend to underestimate the time it will take to get somewhere in a car and overestimate the time it will take to walk somewhere. The time spent cycling in the lot may have seemed less than it actually was, and the time spent walking greater than it actually was—and this could inform how they parked in the future.

In a previous study on a campus parking lot—a lot that was crowded but usually had some spaces in the back rows—Velkey polled students about how long they thought it typically took them to find a parking space. “They said four and a half minutes,” Velkey told me. “In reality, when we watched them, it takes about thirty seconds. I said, ‘Where did that extra four minutes come from?’” Velkey suggests that the psychological principle known as the “availability heuristic” was at work. Students were tending to remember the few times when it was very difficult to find a spot, instead of the everyday experience in which it was quite easy. They were remembering the things that stuck out in their memory.

In the Wal-Mart lot, there was something else interesting about the two groups of parkers. More women seemed to adopt the “cycling” strategy, while more men seemed to opt for the “pick a row, closest space” tactic. Velkey wondered if a “gender effect” existed in the way women and men perceived distance and travel time (previous studies have arrived at mixed conclusions on this). So he gathered a group of subjects and had them estimate the distance to an object at varying locations, and then asked them to estimate the time it would take them to walk there. Men seemed to underestimate how long it would take to walk, while women seemed to overestimate it—which might explain the differences in parking strategies. Both genders underestimated distances, an effect that grew larger as the distance did.

What had led Velkey, clipboard in hand, to parking lots? Interestingly, it was an offshoot of his prime research interest: the foraging behavior of animals, particularly how animals develop certain strategies in the face of constrained resources such as food or territory. He was studying this at the University of Montana, where wildlife abounds. It turned out there was an interesting example right outside the psych department window: the crowded parking lot. The value of the resource was clear—a faculty member had recently spent a day in jail after keying the car of someone who had stolen his parking spot. (Here we must remember the old dictum about what keeps a university running smoothly: “Beer for the students, parking for the faculty, and football for the alumni.”)

In this lot, Velkey saw two kinds of behavior emerge: an active and a passive search strategy. Some people would drive around the lot looking for a space, while others would sit at the head of a row and wait for someone to leave. In terms of the avian foraging models Velkey usually studied, the active searchers were like condors, soaring and looking for prey; the passive searchers, meanwhile, were like barn owls, perched and lying in wait.

Most people were active searchers, spending about as much time looking as it would take them to drive to the next available lot, while the smaller group would wait for minutes on end for someone to exit. This group, Velkey noted, almost always got a spot in the lot, while others found one elsewhere. (In that study the “postacquisition” costs of walking from the car were not measured, so it is hard to say who came out ahead in terms of total time.) A set of “evolutionarily stable strategies” had taken hold: If everyone tried to be condors, they would all be endlessly circling; if everyone tried to be barn owls, they would all be hovering around the same spot. Depending on circumstances (e.g., whether classes were about to let out), one strategy or another might bring more “local” success than another, but, Velkey notes, eventually everyone gets a spot.

The way humans hunt for parking and the way animals hunt for food are not as different as you might think. Many scientists believe that animals’ foraging habits can be explained by a model known as “optimal foraging”—animals seek to gather the most food with the least effort (thus leaving them with more time and energy to, say, reproduce). These strategies evolve in response to the myriad numbers of life-or-death decisions that are made in each successive generation: Does the hunter go after the easy, low-protein prey or the elusive, higher-protein prey? How long does one stay in a particular patch before moving on to a possibly more productive patch? Does one look for food in a group or on one’s own?

For some optimal foraging in your own backyard, consider the bumble-bee and the foxglove. Bees, it turns out, begin looking for nectar in the flowers arrayed on the bottom of the spike, slowly working their way up. Why? Because foxgloves add new flowers in an upward progression, so that those at the top contain less nectar. Bees also know to skip flowers they have already visited, and when a new bee lands on a foxglove that has already been visited by another bee, the odds are it will leave immediately. The chances of finding any missed nectar, it seems, are not worth the effort of looking.

Now, instead of bees, think of humans parking. The parkers in the Montana lot who followed the “perching” strategy had evolved a very specific optimal strategy: They knew that near the top of the hour, as classes emptied, spots would become available, but it was better to search for the exiting driver than the spot. New visitors to the lot, however, or visitors who arrived too late, would circle in vain before ultimately deciding not to expend any more of their energy in this “patch.”

In our daily lives as parkers, we face these foraging questions. We must decide whether to act like condors or barn owls. And we’re sometimes on the other end: It is not difficult to feel unnervingly like dying prey in the eyes of a stalking buzzard when you come out of a crowded shopping mall during the holidays and suddenly find yourself tailed by a creeping car. Is it faster to tail drivers to their cars and wait for them to load their merchandise or to look for an open space? Do we pass up less valuable spaces (i.e, “prey”) for higher-value spaces that might be lurking around the corner? In some cases in the animal world, it is better to hunt for food in groups, but in other cases, going solo is the better option. You may have experienced this dilemma as you cruised the streets of a city (or the rows of a mall) looking for a parking spot, realizing with a sudden dread that the person ahead of you, taillights flashing hopefully in front of potential spaces (which turn out to house fire hydrants or compact cars), is doing exactly the same thing. It no longer makes sense to look in the same places, as the car ahead will consume the resource first—better to head elsewhere.

But neither animals nor humans always follow optimal strategies. One reason is that not enough information might be available—an issue that the parking industry is trying to address with technology that alerts people, via real-time signage or through cars’ navigation systems, to available (paid) parking spaces. Another reason might be the cognitive illusions I have already mentioned. Urban planners have pointed out that people seem willing to walk about a half mile from a parking spot to a destination. But they seem more likely to do so when they’re walking in the massive parking lot to a sports stadium, for example, than on downtown streets. There is an interesting explanation for this: Studies by geographers have shown that people tend to overestimate distances on routes that are “segmented,” versus those where the destination is in sight. Thus a football stadium a half mile away in a big parking lot seems closer than a half-mile walk involving multiple turns in a city.

The Nobel Prize-winning economist Herbert Simon has suggested, in a seminal theory he called “satisficing” (a mix of satisfying and suffice), that because it is so hard for humans to always behave in the optimal way, we tend to make choices that leave us not with the “best” result but a result that is “good enough.” To take the bell-curve parking patterns described earlier as an example, drivers may have entered the lot with a general goal of getting the “best” spot, that is, in the row closest to the entrance. Once they were in the row, however, the goal changed to getting the best spot in that row. This is good in that it helps them feel satisfied with the spot they acquire. But if their strategy to get the “best” spot left them worse off overall, it might not be so good. Simon called the human limitations in making decisions “bounded rationality.” In Velkey’s study, people who focused on finding the “best” parking spot, in terms of distance, failed to account for all the time they were losing while searching—and they didn’t get closer anyway. We do not know if they were happy or not with their spot. When Velkey tried to conduct interviews, he was unsuccessful. Ironically, many people said “they didn’t have time.”

The ways in which we hunt for parking, whatever their biological basis, are one of those subtle, almost secret patterns of traffic. They matter more than you might think.

Parking occupies a strangely marginal place in the whole traffic equation. Engineers focus their energy on traffic-flow models, not parking models. We do not get morning “parking reports” on the radio. We tend to think of traffic as cars in motion; parking spaces seem more like real estate (indeed, they can be priced as high as houses, as the sale of quarter-million-dollar spots in New York and Boston has shown). But the simple, if often overlooked, fact is that without parking there would be no traffic. Every car on the road needs a place where it can begin and end, and mostly just sit there: Cars spend about 95 percent of their time parked.

Parking is the innocuous gateway drug to a full-blown traffic-abuse problem. One survey found that a third of cars entering lower Manhattan were headed to free or subsidized parking spots. If those spots were not free or subsidized, there would be fewer drivers during the morning rush hour. Ironically, near the Department of Transportation itself, the streets are filled with DOT vehicles bearing special parking permits. How much do they add to peak-hour congestion? (This brings to mind a headline from the satirical newspaper the Onion: URBAN PLANNER SITS IN TRAFFIC OF HIS OWN MAKING.)

When the city of Copenhagen was looking to reduce the number of cars entering the central city in favor of bicycles and other modes of transportation, it had a very crafty strategy, according to Steffen Rasmussen of the city’s Traffic and Planning Office: Get rid of parking, but without anyone noticing. From 1994 to 2005, Copenhagen cut parking spaces in the city center from 14,000 to 11,500, replacing the spaces with things like parks and bicycle lanes. Over that same time, not accidentally, bicycle traffic rose by some 40 percent—a third of people commuting to work now go by bike—and Copenhagen has become one of the few places in the world where one can read, in a report, a sentence that would seem like a comical misprint almost anywhere else: “Cycle traffic is now so extensive that congestion on certain cycle tracks has become a problem, as has cycle parking space.”

What you may not realize, when you find yourself driving on a crowded city street, is that many of your fellow drivers on that crowded street are simply cruising for parking. The problem is not so much the lack of street parking but the plentiful abundance of free or underpriced parking. This finding has sparked the fiery crusade of Donald Shoup, a bearded, bow-tied, and bicycling economist at the University of California, Los Angeles, and the author of a seven-hundred-page, cult-sensation tome titled The High Cost of Free Parking.

The mantra used by Shoup, and his growing legion of supporters (dubbed “Shoupistas”), is the “85 percent solution.” In other words, cities should set prices on parking meters at a level high enough so that an area’s spots are only 85 percent occupied at any time. The ideal price, says Shoup, is the “lowest price that will avoid shortages.” Spaces with no meters at all, in a city like New York, are total anathema to Shoup. “People who want to store their car shouldn’t store it on the most valuable land on the planet, for free,” he told me in his office at UCLA, where a vintage parking meter sits atop his desk. “Something that is free is very misallocated.” This is why people who want to see free Shakespeare in the Park performances in New York City have to begin waiting in line as early as the day before (or hire people to do it for them), why cafés that offer free Internet access soon find themselves having to limit the time patrons can spend at a table, and why it can be so hard to find a parking spot.

The reason people cruise is simple: They’re hunting for a bargain. In most cities, there is a glaring gap between the cost of a metered parking spot and that of an off-street parking garage. Looking at twenty large U.S. cities, Shoup has found that, on average, garages cost five times more per hour than metered street spots. The reason garages can charge so much, of course, is that the streets charge so little. When free parking spaces are available, the discrepancy is even higher, particularly for a free spot that can be held for many hours. And so people are faced with a strong incentive to drive around looking for parking, rather than heading into the first available garage.

On the individual level, this makes sense. The problem, as is so often the case in traffic, is that the collective result of everyone’s smart behavior begins to seem, on a larger scale, stupid. The amount of extra traffic congestion this collective parking search creates is shocking. When Shoup and his researchers tracked cars looking for parking near UCLA (they rode bikes, so other cars would not think they were looking for parking and throw off the results), they found that on an average day cars in one fifteen-block section drove some 3,600 miles—more than the width of the entire country—searching for a spot.

When engineers have tried to figure out how many cars in traffic are looking for parking, the results have ranged from 8 percent to 74 percent. Average cruising times clock in at anywhere from three minutes to thirteen minutes. What’s so bad about three minutes? you might ask. As Shoup points out, small amounts can have big consequences. In a city where it takes three minutes to find street parking, and where each space turns over ten times per day, each of those spaces will generate thirty minutes of cruising per day. At 10 miles per hour, that means the average space generates five miles’ worth of driving per day, which works out to a yearly sum that would get you halfway across the United States—not to mention a heap of pollution.

But it is not simply that cars are driving while looking for parking. They’re driving in specific ways. There is the inevitable slowing to check out a prospective spot, the stopping to study whether a spot is valid, the actual jockeying into the spot, or what Shoup calls “parking foreplay,” in which the person detects that a space is about to be vacated and stops to wait. This may seem a minor offense, but as I discussed earlier, one car stopped on a two-lane street creates a bottleneck that cuts traffic capacity in half.

This is worsened further by the inevitable delays and gaps caused by drivers battling to merge before they reach the stalled car. One person’s small act is felt by many. The famed urbanist William H. Whyte once espied this phenomenon during a traffic study of Manhattan. In his “mind’s eye,” he observed, one particular street was always “jammed” with double-parked cars (a result of underpriced parking, in Shoup’s view). But when he actually counted the number of double-parkers, he was shocked to only find “one or two” at any time. “It seemed odd that so few could do so much,” he wrote. “But the number, we found, was not the critical factor. It was the amount of time a lane was out of action because of double parking. Just one vehicle per block was enough.”

The more time one spends looking for parking, of course, the greater chance one has to get in a crash, which then creates even more congestion. Interestingly, parking itself, according to some studies, is responsible for almost one-fifth of all urban traffic collisions. While some engineers think curb parking should be done away with entirely for safety and traffic-flow reasons, others counter that the rows of parked cars actually make things safer for pedestrians, both as a physical barrier and a source of “friction,” like street trees, that can drop traffic speeds by an estimated 8 miles per hour.

To return to the Wal-Mart study mentioned earlier, the massively capacious big-box lots might seem to have little to do with crowded city streets. But there is plenty of cruising in large, free lots. It is simply that the incentive to save money has been entirely replaced by the incentive to save distance (and, theoretically, time, even if that ends up not being the case). In fact, there is always parking at Wal-Marts, so much so that the company lets people in recreational vehicles treat it like a campground. As Shoup points out, at places like Wal-Mart, the planners who dictate what size the parking lot should design for “peak demand”—that is, Christmas Eve—thus guaranteeing that most of the year, the lot has an abundance of empty spaces. The estimated demand comes from the parking-generation models of traffic engineers, which are filled, Shoup notes, with strange irregularities, like the paradoxical fact that banks with drive-up windows are required to have more parking spaces than banks without drive-up windows.

Shoup argues that there is a circular logic at work in parking-generation models, one similar to that found in other kinds of traffic models. The demand for parking is treated as a foregone conclusion: Planners measure the number of people parked at a typical free parking lot in a location without much public transportation. The new Wal-Mart is built and, lo and behold, it attracts lots of cars. As Shoup writes, “The parking demand at new land uses with free parking then confirms the prediction that all the required spaces are ‘needed.’” Planners seem to ignore the fact that they are helping to dictate demand by providing supply. There are lots of cars in lots because parking is free.

As Shoup reminds us, though, Wal-Mart’s free parking, like the free curb parking in cities, is not really free; the term is an oxymoron. We pay for “free” parking all sorts of other ways—and not just as a surcharge on the goods we buy. Parking lots are not only the handmaidens of traffic congestion, they’re temperature-boosting heat islands, as well as festering urban and suburban floodplains whose rapid storm-water runoff dumps motor oil and carcinogenic toxins like polycyclic aromatic hydrocarbons (from shiny black sealcoat) into the surrounding environment and overwhelmed sewer systems. They represent a depletion of energy and a shockingly inefficient use of land—in a study of one Indiana county, Bryan Pijanowski, a geographer at Purdue University, found that parking spaces outnumbered drivers by three to one. The whole parking equation is like a large-scale version of that person at the mall, circling to get a “better” spot to save time and energy, and not realizing how much time and energy they have wasted looking for a better spot.

Traffic patterns are the desire lines of our everyday lives. They show us who we are and where we are going. Examined more closely, this movement, like all desires, is not always rational or efficient. Traffic is a great river of opportunity, but often, as with the poor choices made with parking policy, we’re just spinning our wheels. In the next chapter, we’ll look at some more ways to get unstuck.