Collective Dynamics (E-Journal)
Not a member yet
185 research outputs found
Sort by
A Method for Joint Estimation of Homogeneous Model Parameters and Heterogeneous Desired Speeds
Full text linkOne of the main strengths of microscopic pedestrian simulation models is the ability to explicitly represent the heterogeneity of the pedestrian population. Most pedestrian populations are heterogeneous with respect to the desired speed, and the outputs of microscopic models are naturally sensitive to the desired speed; it has a direct effect on the flow and travel time, thus strongly affecting results that are of interest when applying pedestrian simulation models in practice. An inaccurate desired speed distribution will in most cases lead to inaccurate simulation results. In this paper we propose a method to estimate the desired speed distribution by treating the desired speeds as model parameters to be adjusted in the calibration together with other model parameters. This leads to an optimization problem that is computationally costly to solve for large data sets. We propose a heuristic method to solve this optimization problem by decomposing the original problem in simpler parts that are solved separately. We demonstrate the method on trajectory data from Stockholm central station and analyze the results to conclude that the method is able to produce a plausible desired speed distribution under slightly congested conditions
Incorporation of elevator evacuation from a specific floor – A numerical study of an office building
Full text linkThis paper investigates evacuation from a specific floor plan to determine if elevators can replace one of the escape routes consisting of a staircase without lengthening the evacuation times. This study specifically studies evacuation from one single office floor with 360 and 540 occupants, designed as one fire compartment with an area of 2800 m2. To specify the occupants’ willingness to use the elevator for evacuation from different floors, three different functions are used. These functions are modified to include more floors and are used to derive different distributions for the proportion using staircases and elevators, by simulations in Pathfinder. Two setups are studied. First, three staircases are used for evacuation. Secondly, one staircase is replaced with five evacuation elevators with capacity for eight occupants, and one elevator for sixteen occupants. For these setups, evacuation is studied from the 2nd, 8th, 16th, 25th and 50th floor. In addition to the studied functions, distributions that minimize the evacuation time for each floor are derived from the simulations. These distributions give the shortest possible evacuation times. The distributions are then compared to evacuation simulations from the first setup, only utilizing the three staircases. The results show that for the elevators to fully replace a staircase, between 45-60 % of the floor occupants need to use the elevators when the occupant count is 360, and 43-50 % when the number of occupants is 540. However, these values are dependent on floor number. Compared to the functions studied, the optimal percentage is significantly higher for lower floors, becoming closer to the functions as they increase with higher floor numbers. For each distribution on every floor, queuing time was also studied. Based on the results from the calculations, the study concludes that six evacuation elevators could replace one staircase on the studied office floor. However, this result relies on a certain percentage of the occupants using elevators for evacuation
Modelling Emergency Evacuation of Classroom with Different Age Profiles
Full text linkEvacuation characteristics of pedestrians can be captured under two different conditions - one in immediate and another in non-immediate. The safe and quick evacuation of pedestrians from a building in any situation depends on pedestrian and building characteristics. Understanding the behaviour of pedestrians in emergency situations such as earthquake or fire accident helps in designing buildings for safe evacuation. In view of the limited research on this problem in the Indian subcontinent, this study aims to capture the pedestrian flow characteristics in emergency situations by conducting several experiments in a classroom environment. As a part of the experimental study, the students were instructed to behave as if they were in an emergency evacuation situation. Data was collected on pedestrians with different age profiles such as high school, under graduate and post graduate students considering various scenarios that includes different door widths. Several factors such as number of pedestrians, width of the door, average age of the pedestrians, Body Mass Index, proportion of females, number of students and classroom capacity are considered and their influence on evacuation characteristics was analysed. Based on the observations, an evacuation model has been developed using least square error method. Results show that the variables such as door width and number of students are crucial in representing evacuation time of the classroom. It was found that the relationship between total evacuation time (TET) and door width is represented by power function. This is contrast to the findings of existing literature which shows that the relationship between flow and door width is linear. Our results are best supported by the fact that the TET is exponentially varying with door width till a particular value and remains constant for further increase in door width which is realistic in nature. It is anticipated that the results of the study would provide guidelines to various agencies on managing evacuations. This can also lead to suggestions on optimization of layouts while designing various building access facilities in an academic environment
Forecasting Visitors’ behaviour in Crowded Museums
Full text linkIn this paper, we tackle the issue of measuring and understanding the visitors’ dynamics in a crowded museum in order to create and calibrate a predictive mathematical model. The model is then used as a tool to manage, control and optimize the fruition of the museum. Our contribution comes with one successful use case, the Galleria Borghese in Rome, Italy
Placing Large Group Relations into Pedestrian Dynamics: Psychological Crowds in Counterflow
Full text linkUnderstanding influences on pedestrian movement is important to accurately simulate crowd behaviour, yet little research has explored the psychological factors that influence interactions between large groups in counterflow scenarios. Research from social psychology has demonstrated that social identities can influence the micro-level pedestrian movement of a psychological crowd, yet this has not been extended to explore behaviour when two large psychological groups are co-present. This study investigates how the presence of large groups with different social identities can affect pedestrian behaviour when walking in counterflow. Participants (N = 54) were divided into two groups and primed to have identities as either ‘team A’ or ‘team B’. The trajectories of all participants were tracked to compare the movement of team A when walking alone to when walking in counterflow with team B, based on their i) speed of movement and distance walked, and ii) proximity between participants. In comparison to walking alone, the presence of another group influenced team A to collectively self-organise to reduce their speed and distance walked in order to walk closely together with ingroup members. We discuss the importance of incorporating social identities into pedestrian group dynamics for empirically validated simulations of counterflow scenarios
Lane Formation Beyond Intuition Towards an Automated Characterization of Lanes in Counter-flows
Full text linkPedestrian behavioural dynamics have been growingly investigated by means of (semi)automated computing techniques for almost two decades, exploiting advancements on computing power, sensor accuracy and availability, computer vision algorithms. This has led to a unique consensus on the existence of significant difference between unidirectional and bidirectional flows of pedestrians, where the phenomenon of lane formation seems to play a major role. The collective behaviour of lane formation emerges in condition of variable density and due to a self-organisation dynamic, for which pedestrians are induced to walk following preceding persons to avoid and minimize conflictual situations. Although the formation of lanes is a well-known phenomenon in this field of study, there is still a lack of methods offering the possibility to provide an (even semi-) automatic identification and a quantitative characterization. In this context, the paper proposes an unsupervised learning approach for an automatic detection of lanes in multi-directional pedestrian flows, based on the DBSCAN clustering algorithm. The reliability of the approach is evaluated through an inter-rater agreement test between the results achieved by a human coder and by the algorithm
Compression of Pedestrian Crowd in Corner Turning Subject experiment-based analysis of walking trajectories
Full text linkIn this study, pedestrian crowd dynamics at corner turns were investigated by analyzing pedestrian trajectories in a subject experiment for building more reliable, general-purpose, pedestrian simulation models. An experiment under laboratory conditions was conducted wherein a pedestrian crowd walked straight for a short distance before turning into a right-angled corner built with partition walls; the opposite sides were unwalled. Trials were performed with different widths and densities of initial participant positions. Finally, the trajectories of the pedestrians were extracted from a video through computer image analysis. The results demonstrated that pedestrian behavior at corner turns depends on lane position, lane distance (from the wall), and crowd density
Measuring social influence and group formation during evacuation process
Full text linkEvacuees are likely to respond and move forming groups. However specific data about grouping is generally unavailable and the relationship between response and movement times and specific groupings are unknown. Using a simple method, we measure behavioural cohesion of occupants during evacuation processes. The case study involves using the method in a bus station, a sport centre and a library. Results suggest that proximity (visual/verbal contact) is an important factor but not decisive in the formation of evacuation groups. Social ties and whether occupants share a target and/or an activity before the alarm are also deemed to be important factors. This study provides an exciting opportunity to advance our knowledge of social influence and group formation during evacuation
Pedestrian collision avoidance with a local dynamic goal
Full text linkWe present here a general formalism for equipping simulated pedestrians with an avoidance mechanism. The central idea is to use a short-range target which is adjusted dynamically depending on the environment and thus modulating the desired velocity of the agent. This formulation can be implemented over any type of existing pedestrian model, being force-based or rule-based. As an example, we implement a simple instance of the formulation which is adjusted to reproduce previous reported and available experimental data of collision avoidance in scenarios of low density. The proposed minimal model shows good agreement with the real trajectories and other macroscopic observables
Bridging the gap Why we need to enhance current simulation models
Full text linkMany models that simulate evacuations are state of the art and provide realistic insight to their users. However, simulating everyday situations, such as visitor flow through a museum or passenger flow through an airport, presents marked challenges; existing models reach their limit here. This contribution will introduce and highlight the gap between existing egress models and the difficulties found simulating, for instance, passenger flow or capacity analysis