Zahra Elahi - MSc. Student, Department of Transportation Engineering, Isfahan University f Technology, Isfahan, Iran
Meisam akbarzadeh - Assistant Professor, Department of Transportation Engineering, Isfahan University f Technology, Isfahan,Iran

In design and analysis, standard references assume the pedestrian flow as unidirectional. In realityhowever, pedestrian flow is usually bi-directional. The main question pursued in this paper is that whetherthe main characteristics of pedestrian flow the same under uni- and bi-directional conditions. In order toachieve this goal, effect of bi-directional stream is investigated on behavior and main parameters ofpedestrian flow. Part of the data for the research was collected via controlled experiments and anotherpart was videotaped from Isfahan walkways. It is shown that under bi-directional condition, mean speedof pedestrians is significantly more than the similar condition under uni-directional regime. Moreover,relative discrepancy between pedestrian speeds in two types of flow becomes evident in densities higherthan 0.6 person/m2. Speed of pedestrians in the majority and minority group were recorded and there fromit was concluded that the density in the vicinity of a person has a greater effect on her walking speedcompared to the opposite flow. In order to avoid colliding to opposite flow, pedestrians try to follow thepreceding person and therefor lines are established within the crowd. Fundamental diagrams are alsoderived for different directional ration. As the index of disorder, entropy was calculated for uni- andbidirectional flows. It was concluded that entropy was lower for bidirectional flows which means thatorder improves under bidirectional regime of flow. This is in accordance with less freedom of movementunder bidirectional regime.

Fundamental diagram, pedestrian flow, bidirectional flow, traversing lines, entropy