Desire Paths

You can tell a lot about people from the paths they build.

You don’t need to travel on a path, when you travel: you can walk or drive off the road. But you’re not really supposed to (you might get yelled at) and given the choice, you’ll usually choose to get where you’re going on the path, if there’s a reasonably direct one. Sometimes the paths we’ve built and the paths we want to walk aren’t the same: this usually results in what’s charmingly called desire paths, the routes you often see worn into grass or other surfaces that result from people choosing a convenient but unsanctioned trajectory. Desire paths are an interesting phenomenon, for a number of reasons: for one thing, they’re a beautifully simple example of the power of crowds to cause an effect that no single member of the crowd may have consciously intended. There was a time when all sanctioned paths were, or had started out as, desire paths, but today they’re exceptions; most paths are designed top-down, and steps are generally taken to prevent the development of crowdsourced alternatives. (I’m not saying this is a bad thing.)

The above is a picture I snapped this afternoon in Sudley, Virginia, between Manassas and Interstate 66, while canvassing for the Obama campaign. Specifically, this picture, which could have been taken anywhere in American suburbia, was shot at the corner of Sudley Manor Drive and Bland Drive (yes, really).

Look at the paths that connect these houses to the outside world. Where do they go? Some simply lead between the front door and the driveway. These are easy enough to interpret: when you come or go from these houses, you are expected to travel by car. There is a sidewalk on Sudley Manor Drive, so it’s possible to walk, but if you arrive at one of these houses on foot you must walk up the driveway, through car space, before reaching the small vestige of pedestrian space by the front door. It’s not impossible, then, to arrive as a pedestrian; it’s just clearly not intended.

Other houses have front walkways that extend from the door of the house to the sidewalk, traversing at least ten yards of empty lawn space. These paths mean something slightly different. True, we can safely assume that almost every pedestrian traveling along these walkways is going between the house and a car parked on the street, but even if we didn’t know that—even if we cropped this picture to obscure the street, and had no idea there were cars parked there—we could tell something from these walkways because of where they don’t go. They don’t go between one house and the next. That doesn’t mean you can’t walk to your neighbor’s house, of course; you just have to either walk over the lawn, which is rude, or walk out to the sidewalk, travel laterally to your neighbor’s house, and then walk up their sidewalk again. If we assume the distance between each house and the street is about ten yards, that’s an extra twenty yards to travel, as compared to a hypothetical direct desire path. But it appears the inhabitants of these houses don’t desire to visit their neighbors.

And in fact it appears they don’t, or so anecdotal evidence (and cultural stereotypes) would suggest. At one door I knocked on, I accidentally asked for the woman who in fact lived next door. The man who lived in the house didn’t recognize the name; he’d never heard of her.

We can’t, of course, conclude that the people who live in these houses, for whom these paths were designed, never travel to other houses on their block. But we can conclude from how difficult they’ve made it to do so that their primary paths lead elsewhere. So where were these paths optimized to take people?

At one point during the afternoon I spent wandering Sudley, I found it necessary to travel from one point on Jamaica Lane to another on Castle Road, only a few hundred yards as the crow flies. But the roads in Sudley aren’t designed as the crow flies. In a rectilinear street grid, like that found in almost all American cities outside the old colonial settlements of New England, the shortest-distance path between two points along city roads will closely approximate a bird’s path. This is the optimal street layout when people might want to go anywhere. But if you’re optimizing a street grid to connect a number of individual points to just a few far-off destinations, rectilinear street grids no longer have a clear advantage over other possible layouts. If another goal is to keep travelers off streets they don’t live on, then rectilinear street grids are at a clear disadvantage relative to the “dendrite” pattern, which is the dominant street layout in North American and Australian suburbs.

Dendrite street layouts are built on a hierarchy of street types. Most numerous are the cul-de-sacs, dead-end streets with only one point of access. Despite their association with 20th-century suburbs, cul-de-sac streets are not a new phenomenon; they were recommended by medieval and ancient writers for their potential to confuse attacking armies. Their use in modern suburbs appears to show, if not an active hostility to visitors, then at least a certain indifference to their plight. These visitors, of course, are given no reason to travel on the cul-de-sac unless their destination lies on it. This is because visitors are assumed to be (and tend to be) drivers in cars; the primary justification for cul-de-sacs in modern suburbs is that they keep car traffic off residential streets. This allows children to play in the street with decreased noise, air pollution, and danger from passing cars, compared to car-dependent areas with more gridlike street systems. Developers also prefer to build cul-de-sacs rather than rectilinear grids because the flexible turns of the streets allow them to build houses on irregular lots and at the edges of natural features and property lines.

The other components of the dendrite street layout are the collector road and its intensifications, the arterial road and the separated-grade highway. (“Grade-separated” means the highway passes over or under other streets but never meets them at intersections, so traffic never has to stop moving to allow the passage of orthogonal traffic.) The type of journey most facilitated by a dendrite street layout is one that passes through every level of this hierarchy: it begins in a house in a cul-de-sac, then traverses the collector road, the arterial, and, if necessary, the highway, at the other end of which the process is reversed. Examples of these types of journeys include a commute to a distant downtown or a pleasure trip to a regional activity center, such as a large mall or a skating rink.

The dendrite structure of Sudley is clearly visible in the map above: Jamaica Lane and Copeland Drive are collector roads, Sudley Manor Drive and Williamson Boulevard are small arterials, Sudley Road is a large arterial, and Interstate 66 is a full-on grade-separated highway. The journey I had to make, marked on the map in blue, is not one that the street layout was optimized for. I managed to shorten it significantly by cutting through some grass and over a hill between Jamaica Lane and Colton Lane, but neither an officially sanctioned nor a desire path was available for that route.

Another, more literal barrier I encountered on my walk through Sudley was the impenetrable storm door. Storm doors are those transparent doors that occur on the outside of real doors; they’re usually set up with a spring to swing closed if they’re not held open. Some storm doors can be locked shut. Many houses in Sudley had no doorbells. When these two conditions occurred together, it became impossible to knock on a house’s door; the inhabitants of that house literally could not be reached by conventional non-electronic means. The only way to reach them would be to call, email, or text, or otherwise speak to them when they’re already out. It’s a small thing, this impenetrability; after all, visitors unknown to a house are rare and often unwanted. But, again, it speaks to that house’s priorities: apparently the inhabitants’ desire to be undisturbed by strangers trumps their desire to be accessible to their neighbors or any other human being who might find his or her way to their door unnanounced.

I couldn’t help but think, as I tramped through the cul-de-sacs of Sudley, that this street layout alone represents a certain withdrawal from the collective project humanity has been pursuing for tens of thousands of years, the project of figuring out ways to live together with other human beings. Not to say that the inhabitants of these houses never interact with other people, but, judging by the design of the landscape, these interactions essentially occur on two levels, family and regional. Family interactions occur inside the house, or around it; interactions with others (friends, coworkers) occur at a large remove from the house, or occasionally inside the house. There is no intermediate level of sociability: no local or neighborhood level. The inhabitants of these houses have constructed paths that disconnect them from the world at large and connect only tightly controlled spaces of interaction.

In 2009, Virginia banned cul-de-sacs in new developments. Desire paths change over time, just as desires do. Sooner or later, sanctioned paths shift to follow suit.

Cross-posted from Empire Avenue.


One Response to “Desire Paths”

  1. I want a subscription to your brain.

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