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Virtual geographic environments (VGEs) are extensively used to explore the relationship between humans and environments. Crowd simulation provides a method for VGEs to represent crowd behaviors that are observed in the real world. The social force model (SFM) can simulate interactions among individuals, but it has not sufficiently accounted for inter-group and intra-group behaviors which are important components of crowd dynamics. We present the social group force model (SGFM), based on an extended SFM, to simulate group behaviors in VGEs with focuses on the avoiding behaviors among different social groups and the coordinate behaviors among subgroups that belong to one social group. In our model, psychological repulsions between social groups make them avoid with the whole group and group members can stick together as much as possible; while social groups are separated into several subgroups, the rear subgroups try to catch up and keep the whole group cohesive. We compare the simulation results of the SGFM with the extended SFM and the phenomena in videos. Then we discuss the function of Virtual Reality (VR) in crowd simulation visualization. The results indicate that the SGFM can enhance social group behaviors in crowd dynamics. [ABSTRACT FROM AUTHOR]

The congestion risk during escalator transfers was simulated based on a modified social force model. A four-stage transfer model was proposed. A projection strategy was employed to calculate the social forces for inclined surfaces, and a schedule-line model was proposed to calculate the targets adaptively. Realistic simulations of escalator transfer activities were achieved. The results demonstrate that the spatial distribution of the congestion risks is inhomogeneous. A few areas contain clearly higher risks, and the congestion risk is higher in the transfer aisles than on the escalators. The congestion risk in the transfer aisle is influenced more by the average pedestrian speed than that of the escalators. Slower walkers in the transfer aisle may cause congestion, which is more serious when the escalator speed is faster than that of the pedestrians. Therefore, to reduce the congestion risk, the speed of the escalator should be set slower than the average speed of the pedestrians, and conductors can be employed to divert the traffic at the entrance, turns, and exit of the escalator. [ABSTRACT FROM AUTHOR]

Abstract: A type of trampling process that is caused by picking-up activities during escalator transfers was studied in this paper. A five-stage trampling model for individual pedestrians was proposed, and the social force model was modified considering the transfer features. Several scenarios were simulated to study the impacts of 4 factors, namely, pedestrian traffic, escalator velocity, picking-up duration and pedestrian velocity, on trampling probability. The results show that pedestrian traffic strongly affects the trampling probability, with a positive correlation throughout all scenarios; the picking-up duration affects the trampling probability, with a negative correlation throughout all scenarios; lower pedestrian velocities can result in higher trampling probabilities if the picking-up duration is short; and the escalator velocity may also affect the trampling probability, but there are no general rules for all scenarios. Thus, the impacts of these 4 factors can be queued in descending order as follows: pedestrian traffic picking-up duration pedestrian velocity escalator velocity. Countermeasures can be employed according to the results to reduce trampling risks. [Copyright &y& Elsevier]

Few studies have focused on the evacuation of multi-floor classroom buildings in a primary school, a process that differs from evacuations in other buildings. A stair-unit model was proposed to describe the spatial topology of twisting stairwells and to describe the spatial relationship between stairwells and floors. Based on the stair-unit model, a schedule-line model was proposed to calculate evacuation paths in stair-units; a modified algorithm to calculate pedestrian forces were proposed to describe the evacuee movements in stairwells; and a projection strategy was proposed to model the 3-dimensional evacuation process in multi-floor buildings. The simulated processes were compared with a real evacuation drill. The results showed that the simulated process achieved qualitative and quantitative consistencies with the real drill, proving the appropriateness of the proposed models and algorithms. Based on the validation, further simulations were conducted and a few rules for evacuations in stairwells were identified including rules governing the impact of the moment of entering a staircase, the number of students in a class, the stagger strategy, and the layout of grades on different floors on the time in stairwell and the total evacuation duration. The results can be used to mitigate the effects of a fire disaster, and the proposed models and algorithms can also be referenced by evacuation simulation for other multi-floor buildings such as residential buildings. [ABSTRACT FROM AUTHOR]

In emergency evacuations, not all pedestrians know the destination or the routes to the destination, especially when the route is complex. Many pedestrians follow a leader or leaders during an evacuation. A Trace Model was proposed to simulate such tracing processes, including (1) a Dynamic Douglas–Peucker algorithm to extract global key nodes from dynamically partial routes, (2) a key node complementation rule to address the issue in which the Dynamic Douglas–Peucker algorithm does not work for an extended time when the route is straight and long, and (3) a modification to a follower’s impatience factor, which is associated with the distance from the leader. The tracing process of pupils following their teachers in a primary school during an evacuation was simulated. The virtual process was shown to be reasonable both in the indoor classroom and on the outdoor campus along complex routes. The statistical data obtained in the simulation were also studied. The results show that the Trace Model can extract relatively global key nodes from dynamically partial routes that are very similar to the results obtained by the classical Douglas–Peucker algorithm based on whole routes, and the data redundancy is effectively reduced. The results also show that the Trace Model is adaptive to the motions between followers and leaders, which demonstrates that the Trace Model is applicable for the tracing process in complex routes and is an improvement on the classical Douglas–Peucker algorithm and the social force model. [ABSTRACT FROM AUTHOR]