Friday, January 13, 2012

Science of Pedestrian Movements

 An interesting article from the Economist on 'The Wisdom of Crowds' echoes much of the seminal research of William Whyte (City), Edward T. Hall (The Hidden Dimension), and others that have closely studied the behavior of pedestrians and other users of public spaces. The interplay of cultural habits that tells us to step right or left to avoid collisions on a busy street can lead to a certain inherent poetic 'choreography' when viewed. There are different theories on how these actions are coordinated, and the article focuses on new scientific methods for predicting and studying pedestrian movements. 

:: image via The Economist
 As Jane Jacobs mentioned in The Death and Life of Great American Cities this urban realm is likened to a ballet:
"It is a complex order. Its essence is intricacy of sidewalk use, bringing with it a constant succession of eyes. This order is all composed of movement and change, and although it is life, not art, we may fancifully call it the art form of the city and liken it to the dance — not to a simple-minded precision dance with everyone kicking up at the same time, twirling in unison and bowing off en masse, but to an intricate ballet in which the individual dancers and ensembles all have distinctive parts which miraculously reinforce each other and compose an orderly whole. The ballet of the good city sidewalk never repeats itself from place to place, and in any once place is always replete with new improvisations.”
It was interesting, in this context, to remember my recent travels to Europe, namely London, where traffic on the roads occupies the left lane, but as mentioned in the article, there is not a correlation between this and pedestrian movement. While they mention that London follows pedestrians on the right, that is an oversimplification, as it doesn't necessarily follow, at least in my experience. Many people follow the walking to the left, which is culturally learned in the UK, mirroring the driving, but the influx on many non-locals that have their own rules often leads this to degenerate into chaos. Thus there is not a typical rule of thumb - and you are therefore required to be much more actively engaged in the surroundings to navigate successfully.

London Pavement Parkings - (image by Jason King)
As mentioned in the originally referenced article, culture is less important in this process as is habit and repetition: "Mehdi Moussaid of the Max Planck Institute in Berlin, this is a behaviour brought about by probabilities. If two opposing people guess each other’s intentions correctly, each moving to one side and allowing the other past, then they are likely to choose to move the same way the next time they need to avoid a collision. The probability of a successful manoeuvre increases as more and more people adopt a bias in one direction, until the tendency sticks. Whether it’s right or left does not matter; what does is that it is the unspoken will of the majority."

The importance of this sort of study (sorry thought, as mentioned, this not a 'youngish field') has long been known in urban realms. It is being rediscovered by other sciences and disciplines (seems like everyone wants to study the city now!) such as physics, who are using modeling in the context of crowd safety, particularly in a more multi-cultural world, to better understand what has long been studied the old-fashioned way - by watching people in person or through video.

While thinking of people in similar terms of particles may be helpful, as people are governed by many rules - there is somewhat of a wildcard element in human behavoir as people act as "particles with a 'will'", doing sometimes unpredictable things and non-linear behaviors. The issues with modeling are obvious, when you take into account the sheer number of variables at play even in the most simple pedestrian-to-pedestrian interaction. The article mentions this in the context of a study between Indian and German pedestrians, where the direction is also complicated by cultural spatial rules as well:
"Trying to capture every element of pedestrian movement in an equation is horribly complex, however. One problem is allowing for cultural biases, such as whether people step to the left or the right, or their willingness to get close to fellow pedestrians. Trying to capture every element of pedestrian movement in an equation is horribly complex, however. One problem is allowing for cultural biases, such as whether people step to the left or the right, or their willingness to get close to fellow pedestrians. An experiment in 2009 tested the walking speeds of Germans and Indians by getting volunteers in each country to walk in single file around an elliptical, makeshift corridor of ropes and chairs. At low densities the speeds of each nationality are similar; but once the numbers increase, Indians walk faster than Germans. This won’t be news to anyone familiar with Munich and Mumbai, but Indians are just less bothered about bumping into other people."
It would be interesting to do a lit review of cultural spatial studies, building on the work of Hall, to see if these have been updated, and if we have learned anything new in the past 20 years, since The Hidden Dimension was published in 1990. The world has changed dramatically and is much more global, thus it makes sense that even this sort of revolutionary study, while still somewhat applicable, will have changed due to a changed world. This goes as well to updating Whyte's classic video studies of public spaces (i.e. The Social Life of Small Urban Spaces), which are great but extremely dated and not reflective of a much more culturally rich society. A screen shot of one of the videos shows a different environment than what exists even 20 to 30 years later. This doesn't mean his data are any less relevant, but that we must continue to engage in further study to learn more.



A research agenda that looks at these phenomena, how we use spaces, how we react and incorporate multiple cultural viewpoints, and more is vital to our continual understanding of proxemics, pedestrian movement, crowd dynamics, and more. This can be done by incorporation of more scientific modeling of typically non-urban disciplines, such as the complex modeling processes in physics. It is, to me, much more interesting to envision this study through updates of the seminal urban research studies, which would be a worthy endeavor in our ever globalizing world and our constantly diversifying cities.

This post originally appeared on THINK.urban on January 05, 2012.

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