Not every society reacts to pedestrian congestion the same way. A recent comparison of Germans and Indians revealed that although people from both cultures walk "in a similar manner" when alone, their behavior varies greatly in the presence of others. As one might expect given the densities of their respective countries, Indians need less personal space than Germans do, according to the researchers. As a result, when Germans encountered traffic during a walking experiment, they decreased speed more rapidly than Indians did. "Surprisingly the more unordered behaviour of the Indians is more eﬀective than the ordered behaviour of the Germans," the study concludes (PDF).
Moussaid has found that it's a natural tendency to clump together on the sidewalk. In a 2010 study published in PLoS One, Moussaid and colleagues reported that 70 percent of walkers travel in groups -- a custom that slows down pedestrian flow by about 17 percent. That's because when pedestrian groups encounter space problems on the sidewalk they flex into V-shaped clusters that "do not have optimal 'aerodynamic' features" just so they can continue to talk, according to the researchers.
Other scientists are more interested in the course of an urban journey. In the January issue of Transportation Research Part F, Greek engineer Eleonora Papadimitriou presents a model of typical street-crossing behavior by city pedestrians. Papadimitriou found that people tend to cross major streets either at the beginning or the end of long trips through the city. People who walk fast tend to postpone crossings as long as possible; they're also more likely to cross in the middle of the block. Mid-block crossing rises in frequency with the length of a trip, one-way roads, and curbside parking. As the number of traffic lanes increases, however, we become more likely to cross at an official juncture.
Read the full story at The Atlantic Cities.