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Authors: Tom Vanderbilt

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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.”

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