Single-file Experiments Research Articles

Experimental study on knee and hand crawling evacuation for different age group students

Evacuee motion posture plays an important role in evacuation in a building fire filled with smoke. In a real building fire accident, to prevent harm from the toxic smoke that is spreading along room ceilings, the crawling posture should be adopted by the evacuees. In this paper, we performed an experiment for elementary and middle school students to experience the evacuation process from a building in which a fire broke out and filled with smoke. The aim of this experiment is to investigate the knee and hand crawling (KHC) behavior. Interestingly, the KHC speed of elementary and middle school students is faster than that of college students studied in previous researches. A possible reason for this correlation could be the different experimental requirement for an urgent evacuation, and younger students’ familiarity of crawling motion. The average desired speed of KHC reduces by 54% compared with the upright walking (UW), which proves that the KHC behavior decreases the evacuation efficiency in a building fire. In the single-file experiment, the results show that middle school students have faster KHC speed in free regime than elementary school students. Additionally, middle school students (0.44 s) have smaller adaptation time than elementary school students (0.72 s), which means that middle school students have stronger reaction at small distance. Results of this study can provide the based parameters for human evacuation in a building fire filled with smoke and help to understand the characteristics of KHC behavior for elementary and middle school students.

Single-file pedestrian flow experiments under high-density conditions

In order to investigate the mechanism of uni-directional pedestrian flow, we organize one single-file flow experiment on a ring corridor. With 203 participants, the maximum global density reaches 4ped/m. The fundamental diagrams are given, and compared with that of the single-file experiments held in other countries. We find the pedestrians’ velocities in our experiment are close to the Indian results, and larger than German results. In the time-headway distributions, the peak gradually disappears with the increase of density. At medium densities, the upstream propagation of stop-and-go waves can be observed. The calculated propagation velocity is about 0.4∼0.5 m/s. At extremely high densities, the transition between stopping state and moving state can occur, which is similar to that found in uni-directional experiments with wider system width. In these phenomena, we find there exists one critical density, which is about 3ped/m. All these results can help to learn more about the essence of single-file pedestrian flow.

Experimental study on the single-file movement of mice

Exploring mice movement characteristics is a basic issue of using mice to study crowd behavior in evacuation due to cost and ethical consideration of pedestrian evacuation experiments. In this paper, single-file experiment was performed in a 2m-long passageway with trained mice. Mice movement characteristics were studied by fundamental diagrams in macroscopic view and the velocity–distance headway relation in microscopic analysis. The results show the decaying velocity with density at low densities, and show the non-strict relation of velocity and density at high densities. From microscopic perspective, random pause was observed, and mice can move forward together when overlap occurs. Further, the numerical simulation validates the scattered effect of the random pauses on the velocity–distance headway diagram, and indicates that mice velocity increase with distance headway sharply and then keeps stable. This study provides insights into mice movement as well as the similarities and differences between mice and humans in movement, and it may contribute to crowd evacuation studies.

Unfolding tagged particle histories in single-file diffusion: exact single- and two-tag local times beyond large deviation theory

Strong positional correlations between particles render the diffusion of a tracer particle in a single file anomalous and non-Markovian. While ensemble average observables of tracer particles are nowadays well understood, little is known about the statistics of the corresponding functionals, i.e. the time-average observables. It even remains unclear how the non-Markovian nature emerges from correlations between particle trajectories at different times. Here, we first present rigorous results for fluctuations and two-tag correlations of general bounded functionals of ergodic Markov processes with a diagonalizable propagator. They relate the statistics of functionals on arbitrary time-scales to the relaxation eigenspectrum. Then we study tagged particle local times—the time a tracer particle spends at some predefined location along a single trajectory up to a time t. Exact results are derived for one- and two-tag local times, which reveal how the individual particles’ histories become correlated at higher densities because each consecutive displacement along a trajectory requires collective rearrangements. Our results unveil the intricate meaning of projection-induced memory on a trajectory level, invisible to ensemble-average observables, and allow for a detailed analysis of single-file experiments probing tagged particle exploration statistics.

Dynamic analysis of pedestrian movement in single-file experiment under limited visibility

In this paper, the movement properties of pedestrians under limited visibility are investigated by a group of single-file experiments. Three light transmissions (0.3%, 0.1% and 0.0%) are set and trajectories of individuals are extracted by using tracking algorithm. From the analysis of experimental video, typical behavior of following the boundary and frontal pedestrian are observed under poor visibility. Velocity distribution in different experiment runs conforms to Gaussian distribution. Two regimes are found in the headway–velocity relation and the time-space diagram reveals the evolution of pedestrian traffic with the decrease of visibility. Fundamental diagrams are obtained through the proposed measurement method and three regions can be found in the density-flow relation. The maximum specific flow under the light transmission of 0.3%, 0.1% and 0.0% is 1.3 s−1, 1.15 s−1 and 0.9 s−1 respectively. Finally log transformation for density and velocity is performed to study the elastic effect of density change on velocity change. It is found that pedestrians are more sensitive to the density change under good visibility. This study is helpful to understand pedestrian movement characteristics under different visibilities, which is of practical importance for pedestrian safety under emergency condition. Furthermore, the valuable data obtained from the experiment can be used for model validation and verification in the future.

The stepping behavior analysis of pedestrians from different age groups via a single-file experiment

The stepping behavior of pedestrians with different age compositions in single-file experiment is investigated in this paper. The relation between step length, step width and stepping time are analyzed by using the step measurement method based on the calculation of curvature of the trajectory. The relations of velocity-step width, velocity-step length and velocity-stepping time for different age groups are discussed and compared with previous studies. Finally effects of pedestrian gender and height on stepping laws and fundamental diagrams are analyzed. The study is helpful for understanding pedestrian dynamics of movement. Meanwhile, it offers experimental data to develop a microscopic model of pedestrian movement by considering stepping behavior.

Experimental and modeling study on relation of pedestrian step length and frequency under different headways

It is important to study pedestrian stepping behavior and characteristics for facility design and pedestrian flow study due to pedestrians’ bipedal movement. In this paper, data of steps are extracted based on trajectories of pedestrians from a single-file experiment. It is found that step length and step frequency will decrease 75% and 33%, respectively, when global density increases from 0.46 ped/m to 2.28 ped/m. With the increment of headway, they will first increase and then remain constant when the headway is beyond 1.16 m and 0.91 m, respectively. Step length and frequency under different headways can be described well by normal distributions. Meanwhile, relationships between step length and frequency under different headways exist. Step frequency decreases with the increment of step length. However, the decrease tendencies depend on headways as a whole. And there are two decrease tendencies: when the headway is between about 0.6 m and 1.0 m, the decrease rate of the step frequency will increase with the increment of step length; while it will decrease when the headway is beyond about 1.0 m and below about 0.6 m. A model is built based on the experiment results. In fundamental diagrams, the results of simulation agree well with those of experiment. The study can be helpful for understanding pedestrian stepping behavior and designing public facilities.

Experiment and Modeling of Microscopic Movement Characteristic of Pedestrians

Evacuation models considering microscopic movement characteristics are efficient and helpful for designing safe evacuation facilities, while crucial parameters adopted in the models are important and valuable for calibrating or improving the evacuation models. In this paper, the method and technology for executing and analyzing two crucial controlled experiments, single-file experiment and bottleneck experiment, are reviewed in detail. Based on the observation and some typical characteristics of the single-file experiment, a one dimensional continuous distance model (CDM) was proposed in our previous work and in this study it is improved by introducing the desired walking direction so as to describe the two-dimensional bottleneck movement. Experiment results such as velocity, lateral sway, step frequency vs. distance headway, velocity vs. distance headway, flow, and lane formation are analyzed. In particular, the mode of lane formation is discussed and the critical widths for lane formation are obtained. Comparison between simulation and experiment shows the CDM and its improved version can describe the pedestrian movement very well.