Ing. Pavel Hrabák, Ph.D.

Publikace

Evacuation trials from a double-deck electric train unit: Experimental data and sensitivity analysis

Autoři
Najmanová, H.; Kuklík, L.; Pešková, V.; Bukáček, M.; Vašata, D.; Hrabák, P.
Rok
2022
Publikováno
Safety Science. 2022, 146 ISSN 0925-7535.
Typ
Článek
Anotace
Passenger trains represent a challenging environment in emergencies, with specific evacuation conditions resulting from the typical layout and interior design inherent to public transportation vehicles. This paper describes a dataset obtained in a full-scale controlled experiment emulating the emergency evacuation of a double-deck electric unit railcar carried out in Prague in 2018. 15 evacuation trials involving 91 participants were conducted under various evacuation scenarios considering different compositions of passenger crowd, exit widths, and exit types (egress to a high platform, to an open rail line using stairs, and a 750 mm jump without any supporting equipment). The study’s main goals were to collect experimental data on the movement conditions in the railcar and to study the impact of various boundary conditions on evacuation process and total evacuation time. Movement characteristics (exit flows, speeds) and human behaviour (pre-movement activities, exiting behaviours) were also analysed. The data obtained was used to validate and adjust a Pathfinder model to capture important aspects of evacuation from the railcar. Furthermore, a series of simulations using this model was performed to provide sensitivity analysis of the influence of crowd composition, exit width, and exit type on total evacuation time. As a key finding, we can conclude that for the case of a standard exit path (platform or stairs) the width of the main exit had the greatest impact on total evacuation time, however, crowd composition played the prevailing role in evacuation scenarios involving a jump.

Spatially Dependent Friction—A Way of Adjusting Bottleneck Flow in Cellular Models

Autoři
Hrabák, P.; Gašpar, F.
Rok
2020
Publikováno
Traffic and Granular Flow 2019. Cham: Springer, 2020. p. 103-109. Springer Proceedings in Physics. vol. 252. ISSN 0930-8989. ISBN 978-3-030-55972-4.
Typ
Stať ve sborníku
Anotace
The spatially dependent friction is introduced into cellular floor-field model of pedestrian flow as a possible way of proper adjustment of flow through individual bottlenecks/exits in a rather complex structure containing multiple consecutive bottlenecks of different width. Next to the bulk friction, which is responsible for the conflict-induced delay while walking within the crowd, the local friction is defined individually for each exit-like bottleneck, and is responsible for the clogging in front of the exit. The local friction enables to adjust the flow through given bottleneck according to the observed or estimated value without necessity to change the global parameters. Such method enables to model flow through bottlenecks of similar but different width within one simulation scenario.

Time-headway distribution for random-sequential-update TASEP with periodic and open boundaries

Autoři
Rok
2020
Publikováno
Journal of Traffic and Transportation Engineering. 2020, 7(1), 30-41. ISSN 2095-7564.
Typ
Článek
Anotace
The temporal-headway distribution for Totally Asymmetric Simple Exclusion Process (TASEP) with random-sequential update is investigated. Considering the stationary/steady state of the process, exact formula for the step-headway distribution is derived for conditions when the stationary measure is Bernoulli, i.e., for periodic boundaries and for open boundaries with entering boundary rate alpha and leaving boundary rate beta satisfying alpha + beta = 1. The step-headway formula for general values of boundary rates is calculated numerically by means of the matrix product ansatz.

Exact Formula of Time-Headway Distribution for TASEP with Random-Sequential Update

Autoři
Rok
2019
Publikováno
Traffic and Granular Flow '17. Basel: Springer Nature Switzerland AG, 2019. p. 3-10. ISBN 978-3-030-11439-8.
Typ
Stať ve sborníku
Anotace
The analytical derivation of time-headway distribution for random-sequential totally asymmetric simple exclusion process (TASEP) with periodic boundaries is presented. The finite and periodic nature of the lattice together with the lattice-size-dependent hopping probability related to the random-sequential update does not allow to use common method for the derivation of the time-headway distribution. Another method is presented in this article. The exact derivation of the time-headway distribution leads to several interesting combinatorial tasks. Further, after proper time scaling and using the large L limit we obtain the approximation of the distribution, which can be considered as exact result for TASEP with continuous time.

Pedestrian Flow through Complex Infrastructure, Experiments and Mass-Transport Processes

Autoři
Hrabák, P.; Bukáček, M.; Kielar, P.M.; Borrmann, A.
Rok
2019
Publikováno
Traffic and Granular Flow '17. Basel: Springer Nature Switzerland AG, 2019. p. 159-166. ISBN 978-3-030-11439-8.
Typ
Stať ve sborníku
Anotace
Simple mass-transport model is used to describe the phenomenon of decreasing bottleneck flow during egress of pedestrians through complex infrastructure. The considered mass transport model combines the macroscopic hydrodynamics approach with concept of queuing processes (thus belongs to the class of hand-calculation models). The realisation of such process can be described by means of temporal evolution of the flow through individual bottlenecks and number of pedestrians in front of given bottleneck. These two state variables are used to compare the model prediction with experimental data from two original experiments. The commonly used approach of constant width-related bottleneck capacity cannot capture the observed decrease of flow caused by the loss of motivation while the room is getting empty. Therefore, the dynamical part of the bottleneck capacity derived from the slope of the temporal evolution of the crowd size has been introduced, in order to capture the phenomenon.

Using Raspberry Pi for Measuring Pedestrian Visiting Patterns via WiFi-Signals in Uncontrolled Field Studies

Autoři
Kielar, P.M.; Hrabák, P.; Bukáček, M.; Borrmann, A.
Rok
2019
Publikováno
Traffic and Granular Flow '17. Basel: Springer Nature Switzerland AG, 2019. p. 245-253. ISBN 978-3-030-11439-8.
Typ
Stať ve sborníku
Anotace
The research on pedestrian behavior includes empirical field studies and the methods for data acquisition are versatile. However, a low-budget approach that can be applied to measure pedestrian destination choice in large-scale uncontrolled field studies is still needed. The measurement of destination choice patterns is important for validating strategic models, which explain how pedestrians visit locations to perform activities.We propose a Raspberry Pi approach for WiFi-based measurements without using existing WiFi-infrastructures. The proposed method is useful for recording the microscopic dynamics and macroscopic crowd dynamics of largescale uncontrolled field studies, e.g. public events. Furthermore, we provide concept for strategic model validation that is based on the measured WiFi-signal data.

TASEP with generalized update and Matrix Product Ansatz

Autoři
Rok
2018
Publikováno
SPMS 2018 - Stochastic and Physical Monitoring Systems, Proceedings of the international conference. Praha: CTU. Czech Technical University Publishing House, 2018. p. 35-42. ISBN 978-80-01-06501-3.
Typ
Stať ve sborníku
Anotace
The steady-state distribution of Totally Asymmetric Simple Exclusion Process (TASEP) model has been studied by means of Matrix Product Ansatz (MPA) for variety of updates: random-sequential, parallel, backward-sequential. However, the newly developed generalized update has been studied very poorly. The contribution summarizes the method of MPA and defines the equations following from the MPA concept. Two different solutions of the matrix algebra are presented: by Hrabak and Krbalek (2014) from unpublished dissertation, and Aneva and Brankov (2016). Both concepts are compared and (dis)advantages and limitations discussed.

Mass Transport Processes and Bottleneck Flow

Autoři
Hrabák, P.; Bukáček, M.
Rok
2017
Publikováno
SPMS 2017 - Stochastic and Physical Monitoring Systems, Proceedings of the international conference. Praha: CTU. Czech Technical University Publishing House, 2017. p. 37-40. ISBN 978-80-01-06338-5.
Typ
Stať ve sborníku
Anotace
This extended abstract summarises the most important results already presented at EG-ICE 2016 and TGF 2017, see references below. Main focus is given to the application of mass transport processes in pedestrian flow modelling with stress to the bottleneck flow, where jamming and clogging occurs. A simple mass transport process is used to simulate the evolution of the occupancy in small network of rooms during egress process. The model is then compared to experimental data. It is stated that the door width and gradient of the occupancy play the main role.