46
3 Social Forces
Fig. 3.5 Illustration of conventional and improved elements of pedestrian facilities (adapted from
Helbing [25]. Reproduction with kind permission of Springer Publishers.)
better flow. This surprising discovery can be best understood for bottlenecks such as
doors. Here, a funnel-shaped design can reduce disturbances in the pedestrian flow,
which otherwise result when the directions of motion are not well enough aligned
(e.g. when some people approach the door from the front and others from the side).
In the case of busy bi-directional pedestrian flows, the efficiency of motion can
be improved by a series of pillars in the middle. These pillars help to stabilize the
interface between the opposite flow directions, thereby reducing disturbances. The
effectiveness of the design becomes particularly clear in subway tunnels, where
pedestrians move both ways and pillars exist for static reasons.
Finally, an obstacle in the middle of a pedestrian intersection may also improve
the flow. When Peter Molnar and I discovered this, it took us some time to understand this unexpected finding. Eventually we noticed that, at intersections, many
different collective patterns of motion can emerge, for example, clockwise or counterclockwise rotary flows, or oscillatory patterns of the crossing flows. The problem is
that the different collective patterns of motion conflict with each other, so that none
of them are stable. Putting a column in the center increases the likelihood of rotary
flows and thereby increases the overall efficiency of pedestrian traffic. The flow can
be improved even more by replacing a four-way intersection by four intersections of
bidirectional flows, which can be achieved by placing railings in suitable locations.
This encourages a rotary flow pattern, which greatly reduces disturbances.
3 Social Forces
Fig. 3.5 Illustration of conventional and improved elements of pedestrian facilities (adapted from
Helbing [25]. Reproduction with kind permission of Springer Publishers.)
better flow. This surprising discovery can be best understood for bottlenecks such as
doors. Here, a funnel-shaped design can reduce disturbances in the pedestrian flow,
which otherwise result when the directions of motion are not well enough aligned
(e.g. when some people approach the door from the front and others from the side).
In the case of busy bi-directional pedestrian flows, the efficiency of motion can
be improved by a series of pillars in the middle. These pillars help to stabilize the
interface between the opposite flow directions, thereby reducing disturbances. The
effectiveness of the design becomes particularly clear in subway tunnels, where
pedestrians move both ways and pillars exist for static reasons.
Finally, an obstacle in the middle of a pedestrian intersection may also improve
the flow. When Peter Molnar and I discovered this, it took us some time to understand this unexpected finding. Eventually we noticed that, at intersections, many
different collective patterns of motion can emerge, for example, clockwise or counterclockwise rotary flows, or oscillatory patterns of the crossing flows. The problem is
that the different collective patterns of motion conflict with each other, so that none
of them are stable. Putting a column in the center increases the likelihood of rotary
flows and thereby increases the overall efficiency of pedestrian traffic. The flow can
be improved even more by replacing a four-way intersection by four intersections of
bidirectional flows, which can be achieved by placing railings in suitable locations.
This encourages a rotary flow pattern, which greatly reduces disturbances.