3.2.2 Counter-Flows

reference point expressed in people/s. These three characteristics have a relation in the form of

Flow = Speed * Density * Width (Proulx, 2002). There are certain patterns that pedestrians have tendencies to follow. People have a desire to walk with their own, individual speed as long as they are not in a hurry, and the distance between pedestrians varies mainly depending on the density and on how the flow velocity changes. When these factors increase, the acceptable distance between one and another is reduced. Pedestrians can be compared to car drivers, as they often take automated decisions. Which means that they sometimes can take non-optimal decisions, e.g. standing in the way for someone else even though this behavior is time consuming (Helbing, et al., 2001). It has been shown that pedestrians tend to walk along with others more than alone. Since these smaller groups strongly will affect the overall pattern it is important to analyze what typical movement patterns these groups actually have. As many as two-thirds of the people often travels in groups, mostly together with two to four other members. The movement pattern in those groups differs, mainly depending on the density. At lower densities, the people in the group often gather around the one, or two people who speak the most. The group is gathered in a pattern that looks like a V-formation, mainly because everyone in the group should have the opportunity to hear what the others say. At higher densities though, does it become a struggle between social integration and the physical limitations, mainly because the V-shape is not aerodynamic. When the density finally becomes too high the physical limitations wins and the persons are forced to walk in line with each other’s.

3.2.2 COUNTER-FLOWS

One of the many phenomena, or patterns, that pedestrian dynamics generates arises when different flows meet each other. Lanes are often formed when humans are walking in the same direction (Helbing, et al., 2002). When two such lanes meet, and need to cross each other’s, there are tendencies that the facing groups takes into account one another and are forming, effective, penetrating stripes. Those strips reduce the friction and make the movement pattern more energyefficient in order to facilitate the passage for all parties involved. This is a pattern, and a human group behavior that occurs naturally, which suggests that it depends- and relies on an emergency group behavior. Especially people who have grown up in similar environments tend to, in a quick